Watched this in three sittings and loved every minute, it's actually quite relaxing; thanks Richard. I think this board is on it's last legs as the tracks are becoming more and more corroded. It will be an Herculean task next time!
Wow! When I first saw the damage, I thought that was it for the PCB. Watching you working on it shows there's hope even for the badly mangled ones. Looking forward to seeing part 2 of this repair.
It's always a good idea to have a break from a a repair and a time to think about what your doing! Some days I have everything go wrong whatever i do then other days I fix everything I touch! Only thing is I lie awake at night trying to work out what to try next!
That‘s the engineer mindset. I often do problem solving or ponder design ideas while lying in bed, it engages the brain quite a lot and makes you tired. Much better than counting sheep😊
Hi Richard. To make removing lead-free solder easier, mix it with low temperature solder (Low meld temp solder). This solder is available in rods of about 10 to 15 cm. Usually the component comes loose so quickly that it falls off the circuit board by itself. Then, of course, clean the holes. Low meld solder is only there to remove components, so NEVER solder components on a board with this solder. Use your leaded solder for this. I've been using this method for quite some time now and it works time after time without destroying the tracks. Give it a try, I'd say good luck. Greetings from Belgium. Andy.
Great video once again Richard - I find my de-soldering gun will tend to clog less if I keep the motor running for half a second after lifting up from the board. It also reduces any residual solder sticking to the pads. I gotta say that PCB layout isn't the smartest bit of work I've ever seen. You can see how much the short has heated the HV track and destroyed the lacquer, increasing the likelihood of track oxidation, climbing track resistance and a viscous cycle of overheating ...
You may get better results of the vacuum de soldering tool by keeping it active while removing it from the PCB and then waiting a second or two before stopping it may limit the clogging of the tip.
Hi Richard. thanks for the another informative video. This kind of fibereglass PCBs also getting somewhat conductive after burned completely.It'll specially effective in high impedance circuit area like here with arround 680k resistors. you may have more consideration on it.
With all that corrosion it may be that the 95 volt supply arced over in the area of those resistors and there is no other short. The corrosion along the rest of that trace may be because it runs warm normally and that increases the rate of corrosion. Tell the customer to stop taking that mixer board to the beach ⛱️ Regards, David
Yeah it seems likely that the 95V did arc over there, but I still think some sort of liquid was involved in causing that to happen. It is really odd how the apparent corrosion affects that track across the PCB, but not ones running parallel with it. It's like the high (negative) voltage somehow attracted or electrolysed something corrosive out of the air or some odd process like that 🤔
@@LearnElectronicsRepair I've seen similar things with leaky battery cells, more often than not the corrosion will be along the path of electric potential, even though the actual electrolyte is smothering other tracks :)
@@budgiefish Funny thing is is that I am repairing an old PC motherboard where this actually happened from the old BIOS battery leaking. There is practically little damage around where the battery leaked, but instead, considerably further down at distant connections where the liquid never reached but still makes contact with the battery. 🤔
@@LearnElectronicsRepair I think the "corrosion" is most likely the PCB coating being heated to the boiling point by the current going through the track.
I would be very concerned that the carbonised parts of the PCB will be conductive in ways that doesn't match up with the schematic. Very informative video that clearly shows how you process such extensive damage.
@Andrew Eastment Oh please that would be great. Just some hi-res pics of the area of the PCB that burnt (both sides). I'm pretty well confident I figured it all out by a bit of detective work but visible confirmation would be nice. electronicanaria@outlook.com Thanks.
Hi guys. Was there ever a follow up video to this powered mixer repair? One thing that has to be done is to cut out all of the carbonized board because carbon conducts, sometimes this means re-building part of the circuit off of the main board on jumper cables.
Yeah I'm something of a masochist LOL I do enjoy a challenge though, it's good to explore your own limitations and very satisfying if you get a successful result 🙂
@@LearnElectronicsRepair Fully agree. It's not that badly damaged in a way - although I would definitely not run that -95v over that area (cut the existing (bad) traces a good 1/2" away from that burnt bit - the carbonised PCB will have conductivity! - and jumper with a bit of insulated wire). In terms of not accepting a job - I think it's the customer not the repairman that should decide whether the job goes ahead based on value (economic and sentimental), usual caveats attached. Of course some things are simply not feasible to repair (like a NOCO Genius 10 charger which is encapsulated in silicone), and repairman would be well within reason to refuse to repair something hazardous to health too :)
@@budgiefish Actually I will isolate and bypass the entire minus 95V track, and in fact the entire charred area in the +/- 17V circuit, part 2 of the repair coming soon, this part was long enough already at 1hr video 😉
That would also clog up the vacuum desoldering tool way easier as well. I have learnt this by previous experience - if you intend using the vacuum tool do not add additional flux to the joint 😉
Richard, I see that you struggled with the IC and had to butcher it to get it off the board. I recently discovered low melt temperature solder that buys time to extract ICs by mixing the low melt with the normal solder and then pull the IC out of the board with almost no effort. I'd be interested in your opinion of this technique.
Wow, that was a very charred board, guess most would have said NO to this job. Will you be using epoxy to reinforce this area afterwards? When doing work on newer boards it is necessary to use leaded solder to be able to get the plated-through holes clear. Thick leads and small plated through holes with lead-free are a nightmare! I have done work on an HF power amplifier done like this, horrible construction.. When I worked in the industry we were told to cut IC leads and pull them one at a time like you did (no lead-free then) In fact, when using a desoldering tool you can hear when it is blocked, the pump motor 'pitch' rises.. Good luck, it will be good!
Actually I'm just going to bypass the whole charred area. The burnt resistors and tracks that connect to the op-amp and LM393 can be soldered directly to +/-17V which I can find at multiple points in that area, and the relevant IC pins. The -95V I will cut the track at either end and will use wire to connect from one end (R38) to the other end (the IDC connector CONN4), bypassing and isolating the entire corroded track. I will do similar with the other corroded track(s) I can see near the CONN4 connector, if they read open circuit or look really bad.
I do see a little irony in the fact that there's black smoke... on a perfectly good glass fuse. The joys of electronics. Maybe the use of fused resistors would have been handy in this situation. That's about as bad of a burnout as I've seen.
Yeah I get the irony of that, however if you watched the video through, all the evidence indicates that the arcing or burning initially came from the -95V PCB trace that passes underneath the burnt components but is not electrically part of that circuit.
You mentioned that the customer rents out this equipment so he probably has more pieces of this equipment . Would it have been simpler to ask to borrow another piece of this equipment or ask the customer to take a picture of the pcb . Alternatively contact the manufacturer ?
Yes that is another option, though I am pretty sure I worked it all out by detective work, partly to show a possible technique for this type of repair. 😉Another subscriber also offered to send me some hi-res pics after the weekend, so there will be a part 2 video soon.
hi have had alot of ex hire units they do get alot of heavy wear it's far better to have units not all in one decks i under stand why they are like this easyer to get around to giigs
hi it would worry me why did it start the burn out and this is the 2nd time i would have opened the mixer if the pcb could be got it would just be easy to put it a change over i had a betacam a500p the power unit was very un lucky i binned it to stop the bad luck i had with some of this range yes the bad luck went away with the unit it's easyer to find parts for the old betacam digi decks and it save time just doing a change over time is money i have seen alot of hard greace in decks like the betacam sp bvw75 and teac reel to reel deck getting them clean out takes time as they are for me i don't mind the time working on them i say 90% of the betacam sp bvw 75 is jammed up moving parts note i have 30 of them yes the head drums are showing wear over time i have a plan for the decks wear the video is bad the sound on all of them is go channel 3 4 start to play up when the video is bad i have been told by a tec and there no bad channel 3 4 yet on any of them love the video you do
The entire board looks 'damp', maybe worth an ultrasonic bath (can't really make things worse). I bet you have a small scraper, scalpel etc to remove solder resist, I cringe every time you use your probes.
WTF Are you doing still using copper solder removal tape? Don't you have a solder vacuum? You are putting way too much heat into that board. Why on earth do you need flux to desolder? Very bad practices right off the bat.
This is one very powerful, educative diagnostics and repair tutorial. Definitely not one for the hasty, nervous hand. Thank you and stay well.
Thank You 🙂
Watched this in three sittings and loved every minute, it's actually quite relaxing; thanks Richard.
I think this board is on it's last legs as the tracks are becoming more and more corroded. It will be an Herculean task next time!
Wow! When I first saw the damage, I thought that was it for the PCB. Watching you working on it shows there's hope even for the badly mangled ones. Looking forward to seeing part 2 of this repair.
It's always a good idea to have a break from a a repair and a time to think about what your doing! Some days I have everything go wrong whatever i do then other days I fix everything I touch! Only thing is I lie awake at night trying to work out what to try next!
That‘s the engineer mindset. I often do problem solving or ponder design ideas while lying in bed, it engages the brain quite a lot and makes you tired. Much better than counting sheep😊
@@Chief_Engineer I struggle to sleep when trying to figure things out on a repair!!
Hi Richard. To make removing lead-free solder easier, mix it with low temperature solder (Low meld temp solder). This solder is available in rods of about 10 to 15 cm. Usually the component comes loose so quickly that it falls off the circuit board by itself. Then, of course, clean the holes. Low meld solder is only there to remove components, so NEVER solder components on a board with this solder. Use your leaded solder for this. I've been using this method for quite some time now and it works time after time without destroying the tracks. Give it a try, I'd say good luck. Greetings from Belgium. Andy.
that's great Andy, but its expensive. when leaded will do as well.
Nice work Richard. That's some heavy burn damage!
Great video once again Richard - I find my de-soldering gun will tend to clog less if I keep the motor running for half a second after lifting up from the board. It also reduces any residual solder sticking to the pads.
I gotta say that PCB layout isn't the smartest bit of work I've ever seen. You can see how much the short has heated the HV track and destroyed the lacquer, increasing the likelihood of track oxidation, climbing track resistance and a viscous cycle of overheating ...
You may get better results of the vacuum de soldering tool by keeping it active while removing it from the PCB and then waiting a second or two before stopping it may limit the clogging of the tip.
I'll happy to give anything a try if it helps. Thank you
You gotta love the fuses are intact.
Hi Richard. thanks for the another informative video. This kind of fibereglass PCBs also getting somewhat conductive after burned completely.It'll specially effective in high impedance circuit area like here with arround 680k resistors. you may have more consideration on it.
And I tend to just flood the component with solder and pull it out then clean the holes afterwards hopefully not destroying any pads or tracks!
With all that corrosion it may be that the 95 volt supply arced over in the area of those resistors and there is no other short. The corrosion along the rest of that trace may be because it runs warm normally and that increases the rate of corrosion. Tell the customer to stop taking that mixer board to the beach ⛱️ Regards, David
Yeah it seems likely that the 95V did arc over there, but I still think some sort of liquid was involved in causing that to happen. It is really odd how the apparent corrosion affects that track across the PCB, but not ones running parallel with it. It's like the high (negative) voltage somehow attracted or electrolysed something corrosive out of the air or some odd process like that 🤔
@@LearnElectronicsRepair I've seen similar things with leaky battery cells, more often than not the corrosion will be along the path of electric potential, even though the actual electrolyte is smothering other tracks :)
@@budgiefish Funny thing is is that I am repairing an old PC motherboard where this actually happened from the old BIOS battery leaking. There is practically little damage around where the battery leaked, but instead, considerably further down at distant connections where the liquid never reached but still makes contact with the battery. 🤔
@@arthurmann578 I think corrosive gases are involved too :)
@@LearnElectronicsRepair I think the "corrosion" is most likely the PCB coating being heated to the boiling point by the current going through the track.
I have had success using ChipQuick and other low melt solders on multi-pin component removals.
I would be very concerned that the carbonised parts of the PCB will be conductive in ways that doesn't match up with the schematic. Very informative video that clearly shows how you process such extensive damage.
decades ago in my IBM training class the instructor said to us all " never let the smoke out" lol
Hi I happen to have a few of these boards I'm back in work Monday can send some pictures if it will help
@Andrew Eastment Oh please that would be great. Just some hi-res pics of the area of the PCB that burnt (both sides). I'm pretty well confident I figured it all out by a bit of detective work but visible confirmation would be nice. electronicanaria@outlook.com Thanks.
Hi guys. Was there ever a follow up video to this powered mixer repair? One thing that has to be done is to cut out all of the carbonized board because carbon conducts, sometimes this means re-building part of the circuit off of the main board on jumper cables.
You accept rather difficult jobs. Many repair shops would just refuse this kind of job.
Yeah I'm something of a masochist LOL
I do enjoy a challenge though, it's good to explore your own limitations and very satisfying if you get a successful result 🙂
@@LearnElectronicsRepair Fully agree. It's not that badly damaged in a way - although I would definitely not run that -95v over that area (cut the existing (bad) traces a good 1/2" away from that burnt bit - the carbonised PCB will have conductivity! - and jumper with a bit of insulated wire). In terms of not accepting a job - I think it's the customer not the repairman that should decide whether the job goes ahead based on value (economic and sentimental), usual caveats attached. Of course some things are simply not feasible to repair (like a NOCO Genius 10 charger which is encapsulated in silicone), and repairman would be well within reason to refuse to repair something hazardous to health too :)
@@budgiefish Actually I will isolate and bypass the entire minus 95V track, and in fact the entire charred area in the +/- 17V circuit, part 2 of the repair coming soon, this part was long enough already at 1hr video 😉
with desoldering that connector it would go way easier if you used extra flux with the braid will suck the solder better in to the braid
That would also clog up the vacuum desoldering tool way easier as well. I have learnt this by previous experience - if you intend using the vacuum tool do not add additional flux to the joint 😉
Richard, I see that you struggled with the IC and had to butcher it to get it off the board. I recently discovered low melt temperature solder that buys time to extract ICs by mixing the low melt with the normal solder and then pull the IC out of the board with almost no effort. I'd be interested in your opinion of this technique.
Very nice repair.
Idk, he unnecessary scraped the shizz out of the board just guessing at traces instead of peeking under a resistor.
@@VndNvwYvvSvv I lifted all the resistors that the track went under so I could see it went properly
What temp is your iron set to for removing the damaged components?
It’s no Optimus Prime but that’s one hell of a big ole Tranformer❤ 😁
Hello i have a phillips nx5 mini hifi system that has a pulsing power light wont turn on but people are saying the pcb board is gone
It wanted to make it's own resistor!
Wow, that was a very charred board, guess most would have said NO to this job. Will you be using epoxy to reinforce this area afterwards? When doing work on newer boards it is necessary to use leaded solder to be able to get the plated-through holes clear. Thick leads and small plated through holes with lead-free are a nightmare! I have done work on an HF power amplifier done like this, horrible construction.. When I worked in the industry we were told to cut IC leads and pull them one at a time like you did (no lead-free then) In fact, when using a desoldering tool you can hear when it is blocked, the pump motor 'pitch' rises.. Good luck, it will be good!
Actually I'm just going to bypass the whole charred area. The burnt resistors and tracks that connect to the op-amp and LM393 can be soldered directly to +/-17V which I can find at multiple points in that area, and the relevant IC pins. The -95V I will cut the track at either end and will use wire to connect from one end (R38) to the other end (the IDC connector CONN4), bypassing and isolating the entire corroded track. I will do similar with the other corroded track(s) I can see near the CONN4 connector, if they read open circuit or look really bad.
@@LearnElectronicsRepair Yes, probably the easiest and best solution here. D'you know if they had spilled drinks into the board? bad habits..
Hello, your videos are great! Will there be a second part to this video?
Yes, the replacement parts are here - I'll publish soon
what suprises me is that whatever caused that damage didn't blow the fuses in that fusebank nearby
Oh actually two of the fuses are blown, I just didn't mention it, the pair further away from the burnt area, by the TO220 transistor.
@@LearnElectronicsRepair yeah i saw those. that's why i left another comment. power surge perhaps. ac spark. we know what killers they are.
@@frankbaron1608 Yeah I saw your second comment after replying to this one. Just a case of crossed lines. 🙂
52:36 - Richard, I would call this a pin header or connector. A socket has holes to accept pins. I might even call it a plug (but, hardly a socket).
Would you ever put a board like that in an ultrasonic cleaner? Or would you be concerned it would lift the traces and remove labelling?
I'm making part 2 this week - so you will find out soon 😉
Of course we can!
Hello sir,can i send tkd lamda power supply problem to you?,for your explaind video..thank you
Heya, that's a very burned up pcb that's gone be a lot of work too
I do see a little irony in the fact that there's black smoke... on a perfectly good glass fuse. The joys of electronics.
Maybe the use of fused resistors would have been handy in this situation.
That's about as bad of a burnout as I've seen.
Soot*
Looking forward to part 2.
Yeah I get the irony of that, however if you watched the video through, all the evidence indicates that the arcing or burning initially came from the -95V PCB trace that passes underneath the burnt components but is not electrically part of that circuit.
You mentioned that the customer rents out this equipment so he probably has more pieces of this equipment . Would it have been simpler to ask to borrow another piece of this equipment or ask the customer to take a picture of the pcb . Alternatively contact the manufacturer ?
Yes that is another option, though I am pretty sure I worked it all out by detective work, partly to show a possible technique for this type of repair. 😉Another subscriber also offered to send me some hi-res pics after the weekend, so there will be a part 2 video soon.
i searched aila sit and play x4c us 19 pcb wire repair and got this video
hi have had alot of ex hire units they do get alot of heavy wear it's far better to have units not all in one decks
i under stand why they are like this easyer to get around to giigs
Part 2 might be useful, part 1 not so much
55:00 omg 😵💫😵😵
hi it would worry me why did it start the burn out and this is the 2nd time i would have
opened the mixer if the pcb could be got it would just be easy to put it a change over
i had a betacam a500p the power unit was very un lucky i binned it to stop
the bad luck i had with some of this range yes the bad luck went away with the unit
it's easyer to find parts for the old betacam digi decks and it save time just doing a
change over time is money
i have seen alot of hard greace in decks like the betacam sp bvw75 and teac reel to reel
deck getting them clean out takes time as they are for me i don't mind
the time working on them
i say 90% of the betacam sp bvw 75 is jammed up moving parts note
i have 30 of them yes the head drums are showing wear over time
i have a plan for the decks wear the video is bad the sound on
all of them is go channel 3 4 start to play up when the video is bad
i have been told by a tec and there no bad channel 3 4 yet on any of them
love the video you do
scratch my last comment. there's burning around the fuse holders
Wow thats a bad one
The entire board looks 'damp', maybe worth an ultrasonic bath (can't really make things worse). I bet you have a small scraper, scalpel etc to remove solder resist, I cringe every time you use your probes.
Is that Diode dirty or blown? ua-cam.com/video/di3FZ3c7QRM/v-deo.html
You live in a foreign country and don't speak their language? How long have you been there? A week?
No you can't.
Oh I think I can 😉
WTF Are you doing still using copper solder removal tape? Don't you have a solder vacuum? You are putting way too much heat into that board. Why on earth do you need flux to desolder? Very bad practices right off the bat.