That hole is called a via. It connects traces on the back and front of the board. (And internal traces if the board has internal layers.) It has higher resistance, so it would be the first to burn if too much current passes.
Work with electronics all the time. Heres a basic rundown of whats going on. Most PCBs these days are 4 layers. Outer 2 layers are used for signal routing with the 2 internal layers being used as your power/ground planes. The spot where the burn mark is at, is referred to as a test point that is used during manufacturing to verify none of the traces were damaged/shorted out. Basically a robot with metal probes will ohm out the traces between 2 test points one of three things caused those boards to die. 1. They got the board wet and one of the internal power layers that are exposed near the edge was able to find its way to that test point. 2. They shorted one of the comm wires to the probe point, shorting out the board 3. They were way to rough with the board and caused internal cracking that allowed the power layers to short out. My money is on #1 as at 5:48 you can see a very tiny amount of water damage near that connector
Hahaha. Had the same thing happen at chain. The employees are gonna clean and PM walk in. Had entire coils bent over because they brush side to side. Had boards burnt out and leaks in coils. Saving $800 on pm but spending $15k on coil replacement. Doesn’t make sense but makes dollars
Hey Chris. I'm a controls guy, enjoy watching your stuff. Communication issues can be the biggest pain to troubleshoot. Just to give some RS-485 communication info. in case you run into comm issues in the future. Ideally, to avoid having strange issues, the cable should not be standard 18 gauge copper. It should be low capacitance, low impedance shielded communication cable. RS-485 should always have 3 wires landed for communication, the +, the - and one on the GND terminal as well. Often the shield wire is landed on the GND terminal and the GND is connected to an actual ground at only one location on the communication bus. And there should be 120 ohm resistors across the + and - terminals on both ends of the bus. Low baud rates can usually get away with not having everything wired up to the RS-485 spec, but you will never go wrong by having everything done up to the spec.
I dread the day that I am away from my work and I get the call that one of the department heads is wanting those passwords. I am trying to get the intelligen systems installed in all the coolers and freezers that I have to service. While I am doing the change outs they will be going to R448 or R449 depending on what the box will be.
Looks like the bus tranceiver IC (max485 or something) damaged, or one of the protection diodes shorted. There is 24V nex to it. If you have luck, the microcontroller ports not damaged, (the program running on is fine) so the PCBs can be repaired cheaply. You can test the ports with diode tester, ESD diodes connected to the GND and supply voltage 3.3 or 5V (also the microcontroller ports can be tested sometimes if You trace back the tracks. Usually the MCU and the transceiver IC has resistors between TX/RX/RE.
I have to pull stuff like this all the time at my current job, monkeying around with systems that I've never seen before that I've never been trained on. But only because the contractors who come out have no basic diagnostic skills so they charge thousands of dollars to not fix stuff. So after they come and don't fix it, I get asked to look at it and I fix it. I pulled a relay off a PCB last week and cut it open to confirm diagnosis, the relay looked fine, so I'm ordering that part to recommission the board and then at home one night I figured out the actual problem was that I used the wrong page of the wiring diagram to wire it, so my mistake. But the contractor completely failed to identify which wires were which, had no idea how the system worked, failed to identify a severed wire inside a door hinge, and wired it completely wrong demonstrating no understanding of how anything worked. They were charging $2500 to replace a part that wasn't broken and to not actually fix anything. I put the old part back on and once I have the PCB relay I should have it working again for like $40 in the relay and in the cable for the new cable pull. So I would be that kind of guy in the restaurant, but not when I can call a fine contractor such as yourself who can actually fix it.
Mannn!! Now I want that bag! I will have a conversation with my supervisor/owner tomorrow first thing. When you mentioned about the customer cleaning the coils my first guess was yeah they shorted the boards, I would of done the same on this situation. Great video🍻
That little deal will definitely be a learning experience for whoever decided to tear down the evaporator fans not to mention the cost they wouldn’t experienced otherwise. Merry Christmas 🎁 Give puppy some extra belly rubs!
I'm certainly no expert like Clive, but those look like through-hole connections, possibly to the ground plane on the board. If they shorted a wire against that they could have burned something up. If the circuit board in multi-layer it could be that a trace was burned in the middle that isn't even visible from the outside. Wouldn't take much to zap it.
Also, It always catches me off guard when the video isn't sponsored by Sporlan, haha. And gosh, your dog is so beautiful. Australian shepherds are such beautiful, and friendly/energetic, dogs. (And deviously smart as our dog growing up could attest. Sometimes too much for her own good, haha.)
Yes she is extremely smart and very devious, she figures out ways to do what you tell her to do in her own way… 8its hard to explain but she is amazing
Those boards and their circuits look to simple to justify a more expensive multi layere PCB, but it is not impossible. However, lloking at front and back of the board, you are certainly right, this is a thru hole connecting the ground plane across the board. There are likely more connections like this connecting a lot of copper areas to one single ground plane. It may not even be uncommon to have multiple such holes connecting the same plane, just for reduced resistance or sometimes even for better heat conduction. Those ground planes usually serve two purposes, the are a common ground for a number of electrical connections (like your cars body being connected to the batteries negative terminal and only individual + wires going to the loads.) and they provide some shielding for components. Sometimes they are even used as a heat sink to a degree. The ground plane on the front looked like a bus bar along all those connector. So if you get something most likely wet, it can easily short out with some other connection. For such an amount of damage less likely the RS485 pins, but I think there was a + 12 V next to it as well. That one will sure do, and not in favor of the board. Someone with some expertise in electronics may be easily able to fix this board, but that would come with several risks. First of the major ones, in best case it is only that thru hole that got busted, simple fix. But I would not rule out other compoents getting compromised too. There may be unnoticed burnt out resistors, capacitors or even IC chips. And some components may be ok yet, but might have got stressed in a way, that they might blow up anytime between a few minutes and a few months from now. Second one, this is not something someone is doing a home, so who would want to warranty such a repair, not knowing for sure what else may have taken a hit. This is why such a repair would not be viable, unless those boards would be impossible to obtain as a spare part and swapping for something else for some reason is not an option as well.
that's a "via" it's used to connect top with btm layer on the pcb, it's basically a hole with metallization on the inside, sometimes they can have solder in there sometimes they don't, the lack of solder mask and protective coating makes that place vulnerable to corrosion, and that's what i see as far as i can tell - typical corrosion due to high humidity, not sure if it's the customer's fault... but who knows
Considering that the circuit board has a conformal coating and the communication is low voltage maybe it's not from moisture (and the blown via in the circuit board), I would say they try to rewire something.
Thank you for providing this kind of information for free. I worried a bit when I got a notification a few days ago that this is only for members. Your channel is among 3. I've learned the most from inclouding Rick (HVACR Survival)and old Jim Pettinato. Thank you !
By the looks of it, it seems that the 24VAC track on the board with the affected "burnt" via (that's what these through-board connections are called) has corroded away. I can only carefully guess by pausing the video on 6:26. Hopefully these boards find their way back to the manufacturer instead of ending up on a landfill. The manufacturer/designer and electronics OEM have done their best to conformally coat the board, but it seems that this part below the connectors is not coated. This could be prevented in the future by coating this part (by hand even). Why "bare" PC boards are just mounted like this in this environment is kinda beyond me. Ideally you want electronics like this in a separate enclosure with a pack of desiccant, shielded from moisture and the general "hostile environment" that they operate in. Sure it's conformal coated and there was thought put into it, but the rapid temperature changes, vibration of the equipment and general high moisture surroundings are all but ideal for electronics. Take a look at automotive electronics. Everything is sealed in aluminium enclosures on a modular basis with sealed connectors and such... That's not what you want in terms of serviceability, but it might be good idea for the manufacturer to at least let it be an inspiration. Back to the problem at hand: I think that this board can be repaired by a competent engineer. Doesn't need to be ridiculously expensive. Just a wire across the broken part of the track and a bit of solder mask coating the repair. Obviously a good functional test afterwards. Sadly, this still will be uneconomical in today's world.
The lack of conformal coating - especially in that environment - stood out to me as well. Even the new replacement boards seemed like spotty coverage. It looks like they removed the via on the new board, though, so it might be a known failure point for the previous revision.
Social media platform creators make such a big deal (to the point it scares people) of cleaning your coils on home refrigerators and ac condensers. That manager or whoever was probably influenced from those vids. I wonder how dirty the evap really was
New management on one of my job locations, thought it was a good idea to bring his own Refrigeration, HVAC guy who is cheaper to service VRF in the building. He added over 30 extra pounds of refrigerant until he burned up the compressor on a dual stage heat recovery VRF 🤣 $18,000 later 🤣 one week. $100K dollars plus in loss product.. 🤣 I guess the cheap guy ended up not being so cheap.
Hahahaha....we need the password......i totally know your spidey senses were tingling on that one. Sometimes a customer will only learn when handed an expensive bill for their "help". Thise are pretty cool. I've never messed with any of the smart evaps.....it doesn't seem like it would be very hard to navigate through it. Thanks for sharing Chris
Okay, I am 99% sure I know what chain this is, but I won’t say the name. My assumption is that they are struggling to make money. I’m in VA, this national chain has locations here, and I have noticed small things like the bathrooms being broken for months with no repair, or I get sick every time I eat there. It makes me believe they are just barely squeezing by. Tough times right now.
Could be a multi layer board. There can be more traces than just the outside surfaces. Some boards are constructed like a club sandwich with multiple layers of traces.
It's a double sided board. That burn spot was a "via" to connect the trace on the top side of the board with traces on the bottom. Must have shorted it to something to burn it up like that.
Very interesting, the holes are actually called via’s and they are plated to connect that trace to the trace on the back and depending on the board design there can be more between those two layers. That top trace doesn’t look like it went to the com connector wonder what actually made it do that I would hope there was some conformal coating on the board but that could’ve been week after years in use or someone poking the wire in it during install.
I would not give to much to conformal coatings. They are not too reliable especialy directly on top of something soldered. I was guessing furst as well what might have shorted here. But somehow the burn mark also looks like there is a stain like from liquid around it. And while I personally think it is unlikely the serial connection itself shorted, if I have sen it right, there was a + 12 V nearby. So if they, however on earth they managed to do that, got it wet, possibly not only by condensation but maybe by spraing a cleaner, or a mixture of the two, I guess the via or thru hole connection would the the path of leat resistance, or more correct in this case, highest resistance, and burn up. Looking at the board, there is a possibility to have multiple layers, but for this one just the front and back seem to be more likely. also looking at the copper areas on front and back, this is sure a ground plane (especially from how it looks on the back) or on the front something used like a common bus. And if this possibly was the only via to the back, this was kind of the weak link. For this size of plane or bus, i would honestly not have wondered if they would have put multiple vias across that area on the bottom alone. But then, those come with a price, and if technically not absolutely necessary, well, we all know modern days economics of producing such stuff. Also, if the thru hole did not blew out, some other component would have. Results may have varied, except for still the same being broken.
The plating of a via is usually thinner than the tracks, so the plating of a via burning up like a fuse isn't that unusual. If you had a circuit diagram it would be pretty simple to fix that with a bodge wire - even tracing the board out isn't hard as long as it isn't more than a dual-layer board - and I doubt they would have sprung for a multi-layer board for a simple AC controller.
@@alexanderkupke920 if you look there was another Via on the right from the same trace to the copper pour on the back (for all we know it’s ground or it could be 12+).
@@robertbackhaus8911 I think thats why you sometimes also find those plated holes being filled with a spot of solder. Just to get more mass and conductive material in there.
@@oscalerup1129 oh yes, youre right. with the size of the copper in the back I would suer say its ground. But besides what is visible, I wonder what components possibly got fried as well.
Hi Chris, you only performed a continuity test on the data link loop. What should also have been tested is from each data line to other points such as ground. For both boards exhibit the same burn marks I would suspect that the (+) data line is being grounded somewhere, possibly by being pinched or cut through somewhere along its length. If so, this would likely result in the new boards failing in the same manner as the old. That data link may be shielded, but is is also the correct twisted pair and characteristic impedance? Heatcraft does specify the cable to be shielded and twisted pair conforming to RS-485 specification. A 24 AWG shielded twisted-pair is specified. Belden 89841 cable is specified when below -22 degrees F. It appears that the data rate is low enough not to need termination either in the form of a separate electronic part or by a jumper on the circuit boards at the end of the run. From my own experience with data link issues I would leave one end open circuit and test for voltage at the other, both across the pair and between each wire and ground. This will help show up 'hidden' cabling issues causing random or intermittent data loss or corruption that would otherwise be very difficult to diagnose. Measure both DC and AC. There shouldn't be any reading when measuring for DC voltage. It's when you test for AC that the fun starts. Any reading suggest there is a strong magnetic field somewhere along the cable run inducing a voltage in it. If the correct twisted-pair cabling has been used this should not happen. If your meter shows a frequency reading alongside voltage it help determine whether the interference is low frequency mains power caused by the data link cable running parallel to a mains power cable or close to a transformer or motor or if it is a higher frequency a clue to the source of the problem. A high frequency would suggest a switching power supply. Switching power supplies, even wall warts and line lumps can radiate insane amounts of electromagnetic radiation and can corrupt data communications quite easily. I had this problem and solved it my moved a line lump switching power supply away from the cables to stop the data corruption. I've also found VGA monitor cables to radiate quite strongly and cause problems as well.
Tu video de hoy me dejo perplejo nunca había visto este tipo de camaras de refrigeración, en México aún no e visto alguna de ellas, pero muchas gracias por todo tú tiempo y enseñanzas para aprender de toda tú experiencia. Saludos para todo tú equipo, desde Coacalco Edo de México.
@@MrDubje I beg to differ. On the original you can see the one via near the com connection is soldered on the back and the via that shorted / corroded possibly to an internal layer is not soldered. On the new board both vias near the com connections are soldered on the rear and there are plenty of vias that are still clear. It is by design that they sealed those vias up. Either it was missed in the first two board or was an update to the new boards. But it's not just random. And wave soldering is more old school for mostly through hole components. These boards have a few through hole but mostly SMD components and are reflowed.
I agree but as far as firing where dose it get you? You lost a trained employee that has learned a important lesson at this point. You let him go and now your not just out the cost but the cost to train the new person. My 2 cents
They cant even find employees to work you think they care if there employees “brake” something. Noooo these companies have budgets with there services they are fine
At least they have the passwords now😂 I struggle to believe 24v can make those marks. Especially as both did exactly the same thing at the same place. Especially as those marks are nowhere near the circuit tracks something else happened imho.
These Inteligen's always freak me out - thanks for totally simplifying it. Going through the menu tree. Definitely make me feel better for the next one. I gotta service. Cheers.
I like when you show us some of the details of how these machines fail. Cutting open a compressor- awesome. Cleaning or defrosting- satisfying. Discovering little quirks- Interesting.
looks like they got wet, way more than once, to the point of shorting and corroding away the connections. dirty condensate water and whatever they "cleaned" them with sure wouldn't have helped. maybe they used coil cleaner and sprayer, got it everywhere and didn't clean good? could be just nasty condensate water splashing/spraying or even condensation from them playing around. that also looks like a 24Volt DC trace running overtop the larger ground trace, that has the corroded and burnt "via"(it goes to both the blue plugs to left), above that trace is the RS485 com port(black plug), the serial com port voltage is anything from -7 to +12VDC(changes high/low for signaling). there was other damage to the board I could see to the far lower right, including the bare ground wire at bottom right. it was for sure wet with corrosive water/chemicals more than once and it finally broke down the board, coatings and shorted across the different grounds, power/signal terminals. I'm not sure them fiddling with it caused the final issue, nor added up to it going out, it may have already been acting up and caused them to fiddle with it, which in turn got you there. welcome to electronics in an environment they should never be placed to start with!
Those are called VIAs on a circuit board. They tie traces on both sides of the board together. And looking at that board, they are being used to couple the ground planes on both sides of the board together. As for how they got messed up? Who knows, but it doesnt take much of a jolt on a digital line to mess up chips.
In a week costumer goes... Hey so I uhm found these codes in a video online right. And now I don't know why but I think nothing is working any more. Can you help?
Yeah, looks like they connected 24v to wrong header. Kinda poor design on their part not putting protection (diodes) on the non-24v headers. Not defending them doing shit they shouldn’t, but a tech not paying attention could short a board out too. :/
Wow, I cannot believe management took it upon themselves to disassemble the evaporator to clean it. I'm an Assistant Branch Manager at my bank and I do perform some IT and Facility type work, but only the menial work that I feel bad making a tech come all the way out to the branch to do. My butt is not going on the roof to do any work on our package unit. Someone needs a written warning.
Glad it was an easy fix. Although be it an expensive one for the customer. Hope you had fun in Montana and packed some warm clothes, lol. Temps can get brutal there during the winter. Great Video as always Chris.
If you’re an Employee of a Corporate Chain, you have NO Bidnez screwing with Very Expensive HVAC Equipment. Stay in your Lane or Park your Butt in Restaurant.
Interesting, RS-485 is DC-coupled, so there should be a signal ground as well as the data+/- pair. It may mean your chassis may effectively become signal ground (hopefully via an isolating resistor), which can cause comms problems as well due to earth potential differences.
See the spade connector on the right that says chassis gnd. At least that thing connects the two groundplanes on the PCB together. The "burnt" Via (that's what these "thru the board" connections are called) has probably some moisture problem. Sometimes in manufacturing some of the solutions to etch the copper away to make the traces can get trapped inside those vias. The boards work fine for 5 years and then fail because the vias rot away. But that should not be the issue on that via between two groundplanes, there are many more vias connecting the two on the whole board. But: if there is one, there likely is more. And maybe on important stuff two
Heatcraft doesn't have a return program to refurb those controller boards do they? I feel like it would be an easy fix just by the look of it, but obviously somebody injected voltage on that one leg to burn both controllers I can't see low voltage shorting that one side out on both controllers without poping one of the fuses before burning a trace. I did like the fact you mentioned it was an expensive repair, verses the company not scheduling for a regular PM that wouldn't have resulted in damages.
this goes to probe that boards do not like moisture,and not a single fuse to protect them,only a 15 amp non gfi.if the unit is iced up,it will be above 45 deg RT and the defrost will not activate.just my 2 cents.thanks for posting,be safe on your road trip.
Holes are called vias or pass throughs. Allows electrical connection form 1 side of the board to the other. A short or high current demand can burn them out. Most times the vias have solder blobbed in them to assure conductivity. The pathways on the boards are circuit traces.
Been there, done such repairs in the radio communication field. Some fried boards from amateur modifications that's against FCC rules that can levy heavy fines and jail time if caught with a dirty transmitter causing interference with the aircraft, military and public service bands. Some of these badly modified units I could not repair due to both the company policy and FCC rules. That included the police scanners that picked up the old analog cellphone band with modification to get the customers' ESN numbers. Operating a cellphone in the 80's and 90's was expensive.
Chris, you made a big boo-boo right at the start...after saying the customer doesn't need to know passwords you SHOW AND TELL all of us exactly what it is. TWICE!!😅 I suggest a re edit before it gets too far.
Heatcraft has all their info online it’s not a secret if the customer simply googled the Heatcraft password they would find it I just wasn’t going to tell them over the phone
Definetly a multi-layer board probably a loss of insulation between layers and had a flash over, LOI either from moisture or external causes is very likely
That's a 2-sided board and that solder bead is a circuit trace connecting the front circuits to the back circuits... Burn or break that bead (it goes all the way through the board) and it's the same as breaking a surface trace between components...
Electronic circuit boards inside the cool room fan unit look perfect to suffer more breakdown cost more to fix and end up not saving any money in saved power. Great for more service calls!!😂
5:10 - Oof. Those "black holes" are called vias (via in singular form), essentially a connection from a trace in a middle layer of the PCB being brought to the top layer for connection on an exterior layer. NO BUENO!
By the way, my workplace re-opened this past Saturday. Our menu boards are on back-order so we don't have any. The demo crew threw away all our headset batteries except for one, and threw away all our headsets except for two. Exhaust fan STILL hasn't been looked at. Delfield sandwich station STILL has five cuts in its power cord insulation. Problematic oven STILL not replaced, while they were cleaning all the dust and dirt left behind by the contractors they began baking for the next day, and the oven was over 100°F below setpoint, it was "fixed" the same day, for the... Sixth? Seventh?... time this year. We were promised full equipment replacement, we got exactly NOTHING replaced. Our hot cocoa dispenser was "absolutely" getting replaced in April of 2021, still waiting on that one! On the day they began cleanup (Fri) they noticed our walk-in cooler was at 86°F with door shut and locked, the day we shut the store down it was 51°F. The renovation crew plugged back in the water softener that keeps tripping the GFCI (and whose front panel no longer responds to button presses, and it hasn't been properly dispensing salt for over two years). Over a million dollars spent, so we can serve iced coffee like we're freaking bartenders. More electricity use for a tap system, more work for the crew to clean it, even less counter space (that was already lacking), but it's all about aesthetics. On what they loosely defined as "training" last Wednesday, I learned absolutely nothing because the Training Manager (whom I trained) and my new District Manager wanted to talk loudly to each other during the training videos. While there I did speak to someone who was from the Franchisee that was somehow involved in the renovations, and I began asking questions about the exhaust fan (he claims he didn't know), the front door alarm sensor (he didn't know), the walk-in door seal (he didn't know - "You know, you can order that," he said, and I responded with "They were ordered when we had the compressor replaced; we're still waiting.) I told him about the uphill drain pan line, too, and how our "Maintenance" condemned the cooler instead of fixing the drain line. I then told him to go talk to Carmen (Training Manager) and ask her about the list she asked me to make for her when she was Store Manager - a two-and-a-half year old list containing almost all of the concerns, with photos. Every other store's renovation "fell behind schedule," and ours was completed two days ahead of schedule... Don't need to be a rocket scientist to figure out WHY it was done so quickly! 🤬
6:03 the spot that goes through the circuit board, it looks like a through hole to link layers... and that is at least a 3 layer board, if not more. Looks like they heated up and the solder melted.
Looks to me like vias where it's "burned" a via is where it has a path through the board as it's a multilayer board looks like it's corroded and that's shorting or caused a broken connection through the board
Shouldn't DST be set to yes? Since you enter the date and time on the next screen and the TZ, I think it would then be smart enough to know if DST is applied or not to the time? If DST is set to No then it will be an hr off when the jump happens? (but that's just my assumption)
I don’t like boards in my walk-ins i will gut all the digital crap and do oil school controls. My customers go years with no problems …… O but you have to know how to wire it right…… GOOD DAY
-Normal price for job 3-4k
-Idiot pirice 6-7k
-Look on the faces of staff when you tell them its their fault for burning two PCBs...👀
Priceless 🤣😂🤣
Yep. Idiocy increases price.
Just like when they ask for a discount before you even tell them the price... Triple it, then take off 10%. 😁
That hole is called a via. It connects traces on the back and front of the board. (And internal traces if the board has internal layers.) It has higher resistance, so it would be the first to burn if too much current passes.
Work with electronics all the time. Heres a basic rundown of whats going on. Most PCBs these days are 4 layers. Outer 2 layers are used for signal routing with the 2 internal layers being used as your power/ground planes. The spot where the burn mark is at, is referred to as a test point that is used during manufacturing to verify none of the traces were damaged/shorted out. Basically a robot with metal probes will ohm out the traces between 2 test points
one of three things caused those boards to die.
1. They got the board wet and one of the internal power layers that are exposed near the edge was able to find its way to that test point.
2. They shorted one of the comm wires to the probe point, shorting out the board
3. They were way to rough with the board and caused internal cracking that allowed the power layers to short out.
My money is on #1 as at 5:48 you can see a very tiny amount of water damage near that connector
small amount of water in evaporator coil can damage board🤣 why board not in drain pan?
Need to add an "aggravated stupidity charge" to this call, lol.
Hahaha. Had the same thing happen at chain. The employees are gonna clean and PM walk in. Had entire coils bent over because they brush side to side. Had boards burnt out and leaks in coils. Saving $800 on pm but spending $15k on coil replacement. Doesn’t make sense but makes dollars
Hey Chris.
I'm a controls guy, enjoy watching your stuff.
Communication issues can be the biggest pain to troubleshoot.
Just to give some RS-485 communication info. in case you run into comm issues in the future.
Ideally, to avoid having strange issues, the cable should not be standard 18 gauge copper.
It should be low capacitance, low impedance shielded communication cable.
RS-485 should always have 3 wires landed for communication, the +, the - and one on the GND terminal as well.
Often the shield wire is landed on the GND terminal and the GND is connected to an actual ground at only one location on the communication bus.
And there should be 120 ohm resistors across the + and - terminals on both ends of the bus.
Low baud rates can usually get away with not having everything wired up to the RS-485 spec, but you will never go wrong by
having everything done up to the spec.
I dread the day that I am away from my work and I get the call that one of the department heads is wanting those passwords. I am trying to get the intelligen systems installed in all the coolers and freezers that I have to service. While I am doing the change outs they will be going to R448 or R449 depending on what the box will be.
Looks like the bus tranceiver IC (max485 or something) damaged, or one of the protection diodes shorted. There is 24V nex to it. If you have luck, the microcontroller ports not damaged, (the program running on is fine) so the PCBs can be repaired cheaply. You can test the ports with diode tester, ESD diodes connected to the GND and supply voltage 3.3 or 5V (also the microcontroller ports can be tested sometimes if You trace back the tracks. Usually the MCU and the transceiver IC has resistors between TX/RX/RE.
I have to pull stuff like this all the time at my current job, monkeying around with systems that I've never seen before that I've never been trained on. But only because the contractors who come out have no basic diagnostic skills so they charge thousands of dollars to not fix stuff. So after they come and don't fix it, I get asked to look at it and I fix it. I pulled a relay off a PCB last week and cut it open to confirm diagnosis, the relay looked fine, so I'm ordering that part to recommission the board and then at home one night I figured out the actual problem was that I used the wrong page of the wiring diagram to wire it, so my mistake. But the contractor completely failed to identify which wires were which, had no idea how the system worked, failed to identify a severed wire inside a door hinge, and wired it completely wrong demonstrating no understanding of how anything worked. They were charging $2500 to replace a part that wasn't broken and to not actually fix anything. I put the old part back on and once I have the PCB relay I should have it working again for like $40 in the relay and in the cable for the new cable pull. So I would be that kind of guy in the restaurant, but not when I can call a fine contractor such as yourself who can actually fix it.
Mannn!! Now I want that bag! I will have a conversation with my supervisor/owner tomorrow first thing.
When you mentioned about the customer cleaning the coils my first guess was yeah they shorted the boards,
I would of done the same on this situation.
Great video🍻
That little deal will definitely be a learning experience for whoever decided to tear down the evaporator fans not to mention the cost they wouldn’t experienced otherwise. Merry Christmas 🎁 Give puppy some extra belly rubs!
I'm certainly no expert like Clive, but those look like through-hole connections, possibly to the ground plane on the board. If they shorted a wire against that they could have burned something up. If the circuit board in multi-layer it could be that a trace was burned in the middle that isn't even visible from the outside. Wouldn't take much to zap it.
Also, It always catches me off guard when the video isn't sponsored by Sporlan, haha.
And gosh, your dog is so beautiful. Australian shepherds are such beautiful, and friendly/energetic, dogs. (And deviously smart as our dog growing up could attest. Sometimes too much for her own good, haha.)
Yes she is extremely smart and very devious, she figures out ways to do what you tell her to do in her own way… 8its hard to explain but she is amazing
@HVACRVIDEOS Australian sheppered. Herding breed. Extremely smart :) And yes, she is gorgeous.
Those boards and their circuits look to simple to justify a more expensive multi layere PCB, but it is not impossible. However, lloking at front and back of the board, you are certainly right, this is a thru hole connecting the ground plane across the board. There are likely more connections like this connecting a lot of copper areas to one single ground plane. It may not even be uncommon to have multiple such holes connecting the same plane, just for reduced resistance or sometimes even for better heat conduction.
Those ground planes usually serve two purposes, the are a common ground for a number of electrical connections (like your cars body being connected to the batteries negative terminal and only individual + wires going to the loads.) and they provide some shielding for components. Sometimes they are even used as a heat sink to a degree.
The ground plane on the front looked like a bus bar along all those connector. So if you get something most likely wet, it can easily short out with some other connection. For such an amount of damage less likely the RS485 pins, but I think there was a + 12 V next to it as well. That one will sure do, and not in favor of the board.
Someone with some expertise in electronics may be easily able to fix this board, but that would come with several risks. First of the major ones, in best case it is only that thru hole that got busted, simple fix. But I would not rule out other compoents getting compromised too. There may be unnoticed burnt out resistors, capacitors or even IC chips. And some components may be ok yet, but might have got stressed in a way, that they might blow up anytime between a few minutes and a few months from now.
Second one, this is not something someone is doing a home, so who would want to warranty such a repair, not knowing for sure what else may have taken a hit. This is why such a repair would not be viable, unless those boards would be impossible to obtain as a spare part and swapping for something else for some reason is not an option as well.
@@alexanderkupke920 These are definitely multi layers boards. Used to work in PCB manufacturing
that's a "via" it's used to connect top with btm layer on the pcb, it's basically a hole with metallization on the inside, sometimes they can have solder in there sometimes they don't, the lack of solder mask and protective coating makes that place vulnerable to corrosion, and that's what i see as far as i can tell - typical corrosion due to high humidity, not sure if it's the customer's fault... but who knows
Considering that the circuit board has a conformal coating and the communication is low voltage maybe it's not from moisture (and the blown via in the circuit board), I would say they try to rewire something.
If that board has a conformal coating it is microns thick that is corrosion due to moisture that has damaged the thro hole plating simple
@@petenikolic5244 I guess it's possible, but consider it was working before they played with it.
Hard lesson. F around and they certainly found out. 😮
Beautiful aussie pup!
@11:06 “This customer is nuts” 😂😂😂 🌶️’s managers man..
👍 for the 🐶
You checked the comm wires for a continuity loop, but why didn't you check for a short to ground on the comm wires?
Thank you for providing this kind of information for free. I worried a bit when I got a notification a few days ago that this is only for members. Your channel is among 3. I've learned the most from inclouding Rick (HVACR Survival)and old Jim Pettinato. Thank you !
Jim was man when i was in school. He clarified so much. Rick Dave OC Marat they teach alot.
That employee gives DIYers a bad name. What idiot does something like that if you have no idea what you're doing...
customer "can we have the WIFI password"
Chris "NO! BAD CUSTOMER. go clean your room."
By the looks of it, it seems that the 24VAC track on the board with the affected "burnt" via (that's what these through-board connections are called) has corroded away.
I can only carefully guess by pausing the video on 6:26.
Hopefully these boards find their way back to the manufacturer instead of ending up on a landfill. The manufacturer/designer and electronics OEM have done their best to conformally coat the board, but it seems that this part below the connectors is not coated. This could be prevented in the future by coating this part (by hand even).
Why "bare" PC boards are just mounted like this in this environment is kinda beyond me. Ideally you want electronics like this in a separate enclosure with a pack of desiccant, shielded from moisture and the general "hostile environment" that they operate in. Sure it's conformal coated and there was thought put into it, but the rapid temperature changes, vibration of the equipment and general high moisture surroundings are all but ideal for electronics.
Take a look at automotive electronics. Everything is sealed in aluminium enclosures on a modular basis with sealed connectors and such... That's not what you want in terms of serviceability, but it might be good idea for the manufacturer to at least let it be an inspiration.
Back to the problem at hand: I think that this board can be repaired by a competent engineer. Doesn't need to be ridiculously expensive. Just a wire across the broken part of the track and a bit of solder mask coating the repair. Obviously a good functional test afterwards. Sadly, this still will be uneconomical in today's world.
The lack of conformal coating - especially in that environment - stood out to me as well. Even the new replacement boards seemed like spotty coverage.
It looks like they removed the via on the new board, though, so it might be a known failure point for the previous revision.
@@ZyxlianYeah, these are junk design. Blaming the customer is stupid.
Good eye my friend!...........Good eye!
Social media platform creators make such a big deal (to the point it scares people) of cleaning your coils on home refrigerators and ac condensers. That manager or whoever was probably influenced from those vids. I wonder how dirty the evap really was
Looks like corrosion on the Via because they were not filled. Oxidation grew until it shorted across the traces to chassis.
New management on one of my job locations, thought it was a good idea to bring his own Refrigeration, HVAC guy who is cheaper to service VRF in the building.
He added over 30 extra pounds of refrigerant until he burned up the compressor on a dual stage heat recovery VRF 🤣
$18,000 later 🤣 one week. $100K dollars plus in loss product.. 🤣
I guess the cheap guy ended up not being so cheap.
Yep that "cheaper" upfront price is all many people look at and then are shocked later
Dog is always an acceptable interruption.
Came for the HVAC repair, stayed for doggo.
Hahahaha....we need the password......i totally know your spidey senses were tingling on that one. Sometimes a customer will only learn when handed an expensive bill for their "help". Thise are pretty cool. I've never messed with any of the smart evaps.....it doesn't seem like it would be very hard to navigate through it. Thanks for sharing Chris
Okay, I am 99% sure I know what chain this is, but I won’t say the name. My assumption is that they are struggling to make money. I’m in VA, this national chain has locations here, and I have noticed small things like the bathrooms being broken for months with no repair, or I get sick every time I eat there. It makes me believe they are just barely squeezing by. Tough times right now.
Could be a multi layer board. There can be more traces than just the outside surfaces. Some boards are constructed like a club sandwich with multiple layers of traces.
Yeah, those "holes" are just "through holes" they are to connect the layers on each side, and sometimes also internal layers
And each layer is connected to each other through via's. So it looks like the 12 volt rail got shorted out to ground through the via
There is the idiot fee added to the bill
It's a double sided board. That burn spot was a "via" to connect the trace on the top side of the board with traces on the bottom. Must have shorted it to something to burn it up like that.
Very interesting, the holes are actually called via’s and they are plated to connect that trace to the trace on the back and depending on the board design there can be more between those two layers. That top trace doesn’t look like it went to the com connector wonder what actually made it do that I would hope there was some conformal coating on the board but that could’ve been week after years in use or someone poking the wire in it during install.
I would not give to much to conformal coatings. They are not too reliable especialy directly on top of something soldered. I was guessing furst as well what might have shorted here. But somehow the burn mark also looks like there is a stain like from liquid around it. And while I personally think it is unlikely the serial connection itself shorted, if I have sen it right, there was a + 12 V nearby. So if they, however on earth they managed to do that, got it wet, possibly not only by condensation but maybe by spraing a cleaner, or a mixture of the two, I guess the via or thru hole connection would the the path of leat resistance, or more correct in this case, highest resistance, and burn up.
Looking at the board, there is a possibility to have multiple layers, but for this one just the front and back seem to be more likely. also looking at the copper areas on front and back, this is sure a ground plane (especially from how it looks on the back) or on the front something used like a common bus. And if this possibly was the only via to the back, this was kind of the weak link. For this size of plane or bus, i would honestly not have wondered if they would have put multiple vias across that area on the bottom alone. But then, those come with a price, and if technically not absolutely necessary, well, we all know modern days economics of producing such stuff. Also, if the thru hole did not blew out, some other component would have. Results may have varied, except for still the same being broken.
The plating of a via is usually thinner than the tracks, so the plating of a via burning up like a fuse isn't that unusual. If you had a circuit diagram it would be pretty simple to fix that with a bodge wire - even tracing the board out isn't hard as long as it isn't more than a dual-layer board - and I doubt they would have sprung for a multi-layer board for a simple AC controller.
@@alexanderkupke920 if you look there was another Via on the right from the same trace to the copper pour on the back (for all we know it’s ground or it could be 12+).
@@robertbackhaus8911 I think thats why you sometimes also find those plated holes being filled with a spot of solder. Just to get more mass and conductive material in there.
@@oscalerup1129 oh yes, youre right. with the size of the copper in the back I would suer say its ground. But besides what is visible, I wonder what components possibly got fried as well.
Now your customer watched your show and knows the pw. Lol
Great Video. Thank you for sharing
Hi Chris, you only performed a continuity test on the data link loop. What should also have been tested is from each data line to other points such as ground. For both boards exhibit the same burn marks I would suspect that the (+) data line is being grounded somewhere, possibly by being pinched or cut through somewhere along its length. If so, this would likely result in the new boards failing in the same manner as the old. That data link may be shielded, but is is also the correct twisted pair and characteristic impedance? Heatcraft does specify the cable to be shielded and twisted pair conforming to RS-485 specification. A 24 AWG shielded twisted-pair is specified. Belden 89841 cable is specified when below -22 degrees F. It appears that the data rate is low enough not to need termination either in the form of a separate electronic part or by a jumper on the circuit boards at the end of the run.
From my own experience with data link issues I would leave one end open circuit and test for voltage at the other, both across the pair and between each wire and ground. This will help show up 'hidden' cabling issues causing random or intermittent data loss or corruption that would otherwise be very difficult to diagnose. Measure both DC and AC. There shouldn't be any reading when measuring for DC voltage. It's when you test for AC that the fun starts. Any reading suggest there is a strong magnetic field somewhere along the cable run inducing a voltage in it. If the correct twisted-pair cabling has been used this should not happen. If your meter shows a frequency reading alongside voltage it help determine whether the interference is low frequency mains power caused by the data link cable running parallel to a mains power cable or close to a transformer or motor or if it is a higher frequency a clue to the source of the problem. A high frequency would suggest a switching power supply. Switching power supplies, even wall warts and line lumps can radiate insane amounts of electromagnetic radiation and can corrupt data communications quite easily. I had this problem and solved it my moved a line lump switching power supply away from the cables to stop the data corruption. I've also found VGA monitor cables to radiate quite strongly and cause problems as well.
Little hole in the board, is a "via". The trace shorted between vias, apparently. That's odd.
Love your dog❤
Tu video de hoy me dejo perplejo nunca había visto este tipo de camaras de refrigeración, en México aún no e visto alguna de ellas, pero muchas gracias por todo tú tiempo y enseñanzas para aprender de toda tú experiencia.
Saludos para todo tú equipo, desde Coacalco Edo de México.
Feliz Navidad!
Feliz navidad para todos ustedes deseo que estén bien y tengan un extraordinario día cuídense por favor Dios los bendiga.
Interesting. Did you find out what actually shorted it?
Corroded via and the newer board they filled the via with solder to prevent the same issue in the future.
That is probably incidental as the boards get wave-solderded. Some vias will pick up some solder, others don't. It's not by design.
@@MrDubje I beg to differ. On the original you can see the one via near the com connection is soldered on the back and the via that shorted / corroded possibly to an internal layer is not soldered. On the new board both vias near the com connections are soldered on the rear and there are plenty of vias that are still clear. It is by design that they sealed those vias up. Either it was missed in the first two board or was an update to the new boards. But it's not just random. And wave soldering is more old school for mostly through hole components. These boards have a few through hole but mostly SMD components and are reflowed.
Just like most problems the customers create them. ☺
Someone's gonna lose their job (deservedly, IMO) for costing the company quite a bit of money on not only both boards, but your time...
I agree but as far as firing where dose it get you? You lost a trained employee that has learned a important lesson at this point. You let him go and now your not just out the cost but the cost to train the new person. My 2 cents
@@Mikeracing2005 Well said.
They cant even find employees to work you think they care if there employees “brake” something. Noooo these companies have budgets with there services they are fine
At least they have the passwords now😂
I struggle to believe 24v can make those marks. Especially as both did exactly the same thing at the same place. Especially as those marks are nowhere near the circuit tracks
something else happened imho.
I’m guessing water splashed bottom of board from trying to clean up a freeze up
Via was burned, but it takes a lot of current to do that, more than could be passed by water.
Looks like someone landed a power line onto the signal line.
Good find there.nice to have the kit also on hand.most of us dont.
r86 on back of board is popped you can see it peeled back
These Inteligen's always freak me out - thanks for totally simplifying it. Going through the menu tree. Definitely make me feel better for the next one. I gotta service. Cheers.
im pretty sure ive seen those working incased in ice
Damn man. If i had touched that shit at whataburger, i would have been fired on the spot. I hope the chain does some kind of "retraining".
I like when you show us some of the details of how these machines fail. Cutting open a compressor- awesome. Cleaning or defrosting- satisfying. Discovering little quirks- Interesting.
looks like they got wet, way more than once, to the point of shorting and corroding away the connections. dirty condensate water and whatever they "cleaned" them with sure wouldn't have helped. maybe they used coil cleaner and sprayer, got it everywhere and didn't clean good? could be just nasty condensate water splashing/spraying or even condensation from them playing around.
that also looks like a 24Volt DC trace running overtop the larger ground trace, that has the corroded and burnt "via"(it goes to both the blue plugs to left), above that trace is the RS485 com port(black plug), the serial com port voltage is anything from -7 to +12VDC(changes high/low for signaling).
there was other damage to the board I could see to the far lower right, including the bare ground wire at bottom right. it was for sure wet with corrosive water/chemicals more than once and it finally broke down the board, coatings and shorted across the different grounds, power/signal terminals.
I'm not sure them fiddling with it caused the final issue, nor added up to it going out, it may have already been acting up and caused them to fiddle with it, which in turn got you there.
welcome to electronics in an environment they should never be placed to start with!
Great job Chris has always.
Great catch as always ❤
Just seen your puppy come in.
Those are called VIAs on a circuit board. They tie traces on both sides of the board together. And looking at that board, they are being used to couple the ground planes on both sides of the board together. As for how they got messed up? Who knows, but it doesnt take much of a jolt on a digital line to mess up chips.
In a week costumer goes... Hey so I uhm found these codes in a video online right. And now I don't know why but I think nothing is working any more. Can you help?
Yeah, looks like they connected 24v to wrong header. Kinda poor design on their part not putting protection (diodes) on the non-24v headers. Not defending them doing shit they shouldn’t, but a tech not paying attention could short a board out too. :/
Wow, I cannot believe management took it upon themselves to disassemble the evaporator to clean it. I'm an Assistant Branch Manager at my bank and I do perform some IT and Facility type work, but only the menial work that I feel bad making a tech come all the way out to the branch to do. My butt is not going on the roof to do any work on our package unit. Someone needs a written warning.
Love you’re dog
Glad it was an easy fix. Although be it an expensive one for the customer. Hope you had fun in Montana and packed some warm clothes, lol. Temps can get brutal there during the winter. Great Video as always Chris.
If you’re an Employee of a Corporate Chain, you have NO Bidnez screwing with Very Expensive HVAC Equipment. Stay in your Lane or Park your Butt in Restaurant.
Intelligen = sideshow bob kryptonite 😂🤘😂🤘😂
Ha ha , good to see you in the comments Dave!
Interesting, RS-485 is DC-coupled, so there should be a signal ground as well as the data+/- pair. It may mean your chassis may effectively become signal ground (hopefully via an isolating resistor), which can cause comms problems as well due to earth potential differences.
Love Ausy Shepherds.
See the spade connector on the right that says chassis gnd. At least that thing connects the two groundplanes on the PCB together. The "burnt" Via (that's what these "thru the board" connections are called) has probably some moisture problem. Sometimes in manufacturing some of the solutions to etch the copper away to make the traces can get trapped inside those vias. The boards work fine for 5 years and then fail because the vias rot away. But that should not be the issue on that via between two groundplanes, there are many more vias connecting the two on the whole board.
But: if there is one, there likely is more. And maybe on important stuff two
BTW, that hole throught the board that connect both sides is called a "via".
If your contractor bag doesn't have ribbon cable in it, you should stock it with one.
Where's a good place to learn about these intelligen controllers, as well as other types of controllers?
Heatcraft doesn't have a return program to refurb those controller boards do they? I feel like it would be an easy fix just by the look of it, but obviously somebody injected voltage on that one leg to burn both controllers I can't see low voltage shorting that one side out on both controllers without poping one of the fuses before burning a trace. I did like the fact you mentioned it was an expensive repair, verses the company not scheduling for a regular PM that wouldn't have resulted in damages.
this goes to probe that boards do not like moisture,and not a single fuse to protect them,only a 15 amp non gfi.if the unit is iced up,it will be above 45 deg RT and the defrost will not activate.just my 2 cents.thanks for posting,be safe on your road trip.
Holes are called vias or pass throughs. Allows electrical connection form 1 side of the board to the other. A short or high current demand can burn them out. Most times the vias have solder blobbed in them to assure conductivity. The pathways on the boards are circuit traces.
The VIAs being full of solder is normally just a side effect of the assembly process, rather than something intentional.
Did you replace the boards you already have?
Been there, done such repairs in the radio communication field. Some fried boards from amateur modifications that's against FCC rules that can levy heavy fines and jail time if caught with a dirty transmitter causing interference with the aircraft, military and public service bands. Some of these badly modified units I could not repair due to both the company policy and FCC rules. That included the police scanners that picked up the old analog cellphone band with modification to get the customers' ESN numbers. Operating a cellphone in the 80's and 90's was expensive.
FCC is overrated
Who cares about electrical interference
😂😂
Shop Rates:
$100 /hr
$150 / hr if you want to watch
$200 / hr if you want to help
$250 / hr if you already tried fixing it yourself
heatcraft or sporlan??
Chris, you made a big boo-boo right at the start...after saying the customer doesn't need to know passwords you SHOW AND TELL all of us exactly what it is. TWICE!!😅
I suggest a re edit before it gets too far.
Heatcraft has all their info online it’s not a secret if the customer simply googled the Heatcraft password they would find it I just wasn’t going to tell them over the phone
Definetly a multi-layer board probably a loss of insulation between layers and had a flash over, LOI either from moisture or external causes is very likely
That's a 2-sided board and that solder bead is a circuit trace connecting the front circuits to the back circuits...
Burn or break that bead (it goes all the way through the board) and it's the same as breaking a surface trace between components...
There is another imposter where was quality, integrity and tradition what have you done with the real HVAC guy?
Plated thru hole connection from one side to the other is has corroded bit of wire and a soldering iron .
Electronic circuit boards inside the cool room fan unit look perfect to suffer more breakdown cost more to fix and end up not saving any money in saved power. Great for more service calls!!😂
5:10 - Oof. Those "black holes" are called vias (via in singular form), essentially a connection from a trace in a middle layer of the PCB being brought to the top layer for connection on an exterior layer. NO BUENO!
By the way, my workplace re-opened this past Saturday. Our menu boards are on back-order so we don't have any. The demo crew threw away all our headset batteries except for one, and threw away all our headsets except for two. Exhaust fan STILL hasn't been looked at. Delfield sandwich station STILL has five cuts in its power cord insulation. Problematic oven STILL not replaced, while they were cleaning all the dust and dirt left behind by the contractors they began baking for the next day, and the oven was over 100°F below setpoint, it was "fixed" the same day, for the... Sixth? Seventh?... time this year. We were promised full equipment replacement, we got exactly NOTHING replaced. Our hot cocoa dispenser was "absolutely" getting replaced in April of 2021, still waiting on that one!
On the day they began cleanup (Fri) they noticed our walk-in cooler was at 86°F with door shut and locked, the day we shut the store down it was 51°F. The renovation crew plugged back in the water softener that keeps tripping the GFCI (and whose front panel no longer responds to button presses, and it hasn't been properly dispensing salt for over two years).
Over a million dollars spent, so we can serve iced coffee like we're freaking bartenders. More electricity use for a tap system, more work for the crew to clean it, even less counter space (that was already lacking), but it's all about aesthetics.
On what they loosely defined as "training" last Wednesday, I learned absolutely nothing because the Training Manager (whom I trained) and my new District Manager wanted to talk loudly to each other during the training videos. While there I did speak to someone who was from the Franchisee that was somehow involved in the renovations, and I began asking questions about the exhaust fan (he claims he didn't know), the front door alarm sensor (he didn't know), the walk-in door seal (he didn't know - "You know, you can order that," he said, and I responded with "They were ordered when we had the compressor replaced; we're still waiting.) I told him about the uphill drain pan line, too, and how our "Maintenance" condemned the cooler instead of fixing the drain line. I then told him to go talk to Carmen (Training Manager) and ask her about the list she asked me to make for her when she was Store Manager - a two-and-a-half year old list containing almost all of the concerns, with photos.
Every other store's renovation "fell behind schedule," and ours was completed two days ahead of schedule... Don't need to be a rocket scientist to figure out WHY it was done so quickly! 🤬
Now I ask you a question...
Who owns the system / controller / whatever that is?
The owner should always have access to configure their own device.
You clearly didn't't even watch the video. He clearly stated it is a chain restaurant and it was just employees who wanted the pon
That doesn't look like a burn as much as corrosion Moisture may have corroded the via and opened a connection.
6:03 the spot that goes through the circuit board, it looks like a through hole to link layers... and that is at least a 3 layer board, if not more. Looks like they heated up and the solder melted.
You tested continuity, but I didn't see a test of discontinuity with that wago off to ensure no short in the wire?
You might want to start to blur out the PINs in your videos. Just for the case that a customer finds your vids
Looks to me like vias where it's "burned" a via is where it has a path through the board as it's a multilayer board looks like it's corroded and that's shorting or caused a broken connection through the board
i could probably repair that board. but that's water damage for sure
I have question for is do they 2 evaporator coil and 1 condenser unit?
For control board use electrical cleaner, to make sure it's a PCB Cut
Shouldn't DST be set to yes? Since you enter the date and time on the next screen and the TZ, I think it would then be smart enough to know if DST is applied or not to the time? If DST is set to No then it will be an hr off when the jump happens? (but that's just my assumption)
I am thinking some wanna be techno wanted to look good for management. Management said “Let’s give it a try” once stuff got broke everyone got dumb
615 thumbs up Well you just gave them the password.
Why it’s is not grounded ?
Interesting....
The conformal coating looks very thin and not uniform(it’s might have been lighting). Good video
That "burn mark" is 100% corrosion. Not knowing what they were doing, they got that board wet and toasted the RS485 circuit.
I don’t like boards in my walk-ins i will gut all the digital crap and do oil school controls. My customers go years with no problems …… O but you have to know how to wire it right…… GOOD DAY