The flashing looks to me like the board is trying to start up, and the power supply is pooping out when the relays try to pull in and their coils start drawing more current. I'd be very suspicious of every electrolytic in the power supply. Letting it cycle like that may well corrupt the microcontroller's program memory. The boards in these are often coated with something to protect against moisture. Honestly, I'm amazed that the dehumidifier had a refrigerant charge present when you found it. Refrigerant leaks are usually how they fail.
I just got a 70 gal one for $15, the guy still had the plastic cover on it. Said it leaks everywhere but inside the tank … I just saw in your video the tube is optional, removed it, now it empties into the tank 😎👍🏼
Bad filter cap in the power supply. When the relay is supposed to kick in, the voltage drops, and the DC output gets noisy. My oven was doing the same thing. The clock would work, but if you tried the oven, it would behave in a similar way.
Exactly what I was thinking. The power supply have problems and when the micro-controller wake up, it needs too much current and keeps reset itself (well, kind of but it fails to wake up)
Thanks for the advice. I have an ESR meter around here somewhere. Might be easier to just replace them if I have some on hand. I'll reflow all the pads too. Sad that something only 3 years old needs a recap!
@@bandersentv oh yeah!!!! pads reflow is a good idea..... I've repair a Harman Kardon TS-7 on the last year (it's a 150 watts subwoffer for home cinema) and maybe 50% of the preamp/ filter board's soldering was dead.... they were looking good but when using magnifying glass they were all cracked... like a little circular crack on all the soldering right in the middle of the curve and that was one of the main problem of it.... the second problem was the glue that become conductive with look like it's a really common plague... the glue look like neoprene and with the heat it becomes black and conductive.... I replaced the glue with silicone like what is used for bathroom joint.... why they not use that??? No idea at all and what I can tell you??? Well, welcome to new generation garbage product's world!
@@bandersentv Hi, it could be a smoothing capacitor, but it could also be the linear 12 volt regulator (which feeds in series the 5 volt one), if it fails to deliver enough current, when the relay coils start to draw current, the 12v line may drop enough to make the 5 volt regulator oscillate, and the microcontroller board will go into fail mode. Good Luck P.S. Here's the schematic of a very similar power supply, the main difference is the one in your device hasnt got the 9 volt rail; fccid.io/YZJ25190701010/Schematics/Schematics-1382708
My suggestion is to find the power specs on the IC and use a regulated PS to power the upper board with the IC with it disconnected and see if you can reproduce the issue. If not dig into the lower board and ancillary points and check the specs of each component replacing the out of spec ones. Ive been watching your videos for years and know you will find it and we will enjoy watching you do it. Good luck!
I just thought about a repair I did to my Friedrich portable AC. The control panel was nearly dead acting. It has those microswitches like your dehumidifier. I hosed them down with CRC contact cleaner. I rather doubt it will help you, but it won't hurt I'm sure.
Those spade connects occasionally have a locking tab under the shroud. Push it in and it should slide off easily. I would reflow any solder joints of any parts that are heavy that could vibrate and crack any solder joints. Lead free solder sucks. Do you have an ESR meter to test the E caps. The switching power supplies are notorious for killing caps. Check the power supply rails for heavy ripple on them. The ripple could be high frequency like 100khz to 500khz. This will point to bad filter caps also. Look on line there are ton of DIY ESR meter circuits out there. I made one 8 years ago and it is my most valuable test tool. By the way when and where are the local Chicago area hamfests and radio swap meets? THANX. Looking forward to your progress on this.
Resolder power transformer, looks like the secondary connections are cracked in the video. Had similar problems with AC control boards with cracks on the heavy parts making poor contact.
Without even watching the video beyond seeing the initial flickering symptoms, and without reading any comments, as a total beginner in this field, I’m still going to say this looks like a low voltage/power supply issue. I’ve seen digital electronics (in my case, music gear) act exactly like this when voltage supply was low. It will be interesting to see if I’m correct…
Did some troubleshooting tonight. It's a much simpler circuit than I realized. It's just a liner power supply. 12.6 vac transformer, bridge rectifier, 7812 and 7805 regulators with a few caps.
The rapid pulsing is the microcontroller resetting over and over very quickly. Since I doubt it has an external reset signal, the only way it can reset due to hardware is a brown out on the power supply. I suspect that when the microcontroller boots and does the display test where all the LEDs come on at once and the buzzer beeps, this causes the voltage to drop. The microcontroller then resets and turns the LEDs off, the voltage comes back up, and the cycle repeats.
How to operate the 70 pint I turn it on and after a few minutes it shuts off . I have set it on auto 30%,40%,50,60%,70% and it shuts off I changed the settings which has humidity, cycle,timer and delay start which stay on 1 or higher fan speed has auto, high and low. Which is the best way to run this unit it has 35 pt thirsty, 50 thirstier and 70 thirstiest right now its on auto at 50% both fan speed and settings can someone help it look identical to the 50 pint on top of the unit?
Since it was free to start with, unless the 5v is funky I'd probably ditch it or if you can just run it full tilt by hot wiring the fan and compressor. I suppose if you could figure out which wires go to the power board you could get an arduino or something and control it with that.
I'm stuck at those decorative bits of plastic at 2:06. I think I just need to clean the coils but don't want to break anything. How did you get them off?
It seems kinda reversed to me. Usually when cap goes bad it doesn't want to start and after the cap formes a little it startes sort of working, this seems odd. Anyway - I don't see quartz rezonator on the board, so the MCU is probably timed from some RC oscillator, so there is no indication on which speed it runs. The thing is - if it runs on 4 MHz, it needs only 2.2V for supply, if it runs on max 12MHz, it needs 4.5V. Anyway, thats just me babbling around. The problem seems obvious, power supply is crapping out. From what I can see the power transformer is very, VERY poorly soldered so I would start by resoldering the transformer. If that doesn't help, then look into the power supply, one of those caps probably are designed to fail, usually it is the reference cap on primary side of the PSU. Sometimes it takes out the regulator too, but there it seems to be working good since it at least provide some voltage. It is fairly primitive device, no need for schematics, you will figure it out easily. Somebody who knows that much about the hardest electronic device out there (tubes) shouldn't be stopped by simple switching PSU and one MCU :D
@@bandersentv After you finish the predicta build I'd love to purchase it if you are selling it. Love to buy one before the end of summer. I want to hook it up to a DVD player to watch old black and white movies.
Sorry, but I don't think I will have one by then. I have two TVs to restore for someone else. Then not sure which Predicta to restore. That gold siesta I started on is a mess and will take quite a while to finish. The Debutante with stand I showed recently I'm going to keep - at least for a while. The Holiday I recently got is also a major project and is missing legs.
Which predicta build? He's rebuilt/repaired lots of predictas, go watch one of those series. Predicatas are boring, just a typical late 50s-early 60s series string TV set, aside from the Princess/Debutante/Siesta sets which are typical transformer sets from the same era. The only thing that makes them interesting is the styling, other then that the performance, and circuitry, is very average. As for myself I'm hoping that he will fix up his Dumont Clifton, one of the Strombergs, the early Philcos, one of the 10'' Motorolas, the Emersons, or that Sears Silvertone set with loctal tubes in it, but it's his channel. I like it when he restores one of the more unusual sets, same with the radios.
I'm a bit tired of the Predictas too, but they are in high demand. I will tip you off that the next projects are for another client and include a 21" metal cabinet Admiral from the early 50s and a classic bakelite GE 800 "locomotive" from 1949. I think that will be an interesting project.
The flashing looks to me like the board is trying to start up, and the power supply is pooping out when the relays try to pull in and their coils start drawing more current. I'd be very suspicious of every electrolytic in the power supply. Letting it cycle like that may well corrupt the microcontroller's program memory.
The boards in these are often coated with something to protect against moisture. Honestly, I'm amazed that the dehumidifier had a refrigerant charge present when you found it. Refrigerant leaks are usually how they fail.
I just got a 70 gal one for $15, the guy still had the plastic cover on it. Said it leaks everywhere but inside the tank … I just saw in your video the tube is optional, removed it, now it empties into the tank 😎👍🏼
Bad filter cap in the power supply. When the relay is supposed to kick in, the voltage drops, and the DC output gets noisy. My oven was doing the same thing. The clock would work, but if you tried the oven, it would behave in a similar way.
Exactly what I was thinking. The power supply have problems and when the micro-controller wake up, it needs too much current and keeps reset itself (well, kind of but it fails to wake up)
Agreed. If there is a scope, check the power supply rail.
Thanks for the advice. I have an ESR meter around here somewhere. Might be easier to just replace them if I have some on hand. I'll reflow all the pads too. Sad that something only 3 years old needs a recap!
@@bandersentv oh yeah!!!! pads reflow is a good idea..... I've repair a Harman Kardon TS-7 on the last year (it's a 150 watts subwoffer for home cinema) and maybe 50% of the preamp/ filter board's soldering was dead.... they were looking good but when using magnifying glass they were all cracked... like a little circular crack on all the soldering right in the middle of the curve and that was one of the main problem of it.... the second problem was the glue that become conductive with look like it's a really common plague... the glue look like neoprene and with the heat it becomes black and conductive.... I replaced the glue with silicone like what is used for bathroom joint.... why they not use that??? No idea at all and what I can tell you??? Well, welcome to new generation garbage product's world!
@@bandersentv Hi, it could be a smoothing capacitor, but it could also be the linear 12 volt regulator (which feeds in series the 5 volt one), if it fails to deliver enough current, when the relay coils start to draw current, the 12v line may drop enough to make the 5 volt regulator oscillate, and the microcontroller board will go into fail mode. Good Luck
P.S. Here's the schematic of a very similar power supply, the main difference is the one in your device hasnt got the 9 volt rail;
fccid.io/YZJ25190701010/Schematics/Schematics-1382708
My suggestion is to find the power specs on the IC and use a regulated PS to power the upper board with the IC with it disconnected and see if you can reproduce the issue. If not dig into the lower board and ancillary points and check the specs of each component replacing the out of spec ones. Ive been watching your videos for years and know you will find it and we will enjoy watching you do it. Good luck!
Great to see a video, Bob. hope u r well.
I just thought about a repair I did to my Friedrich portable AC. The control panel was nearly dead acting. It has those microswitches like your dehumidifier. I hosed them down with CRC contact cleaner. I rather doubt it will help you, but it won't hurt I'm sure.
Those spade connects occasionally have a locking tab under the shroud. Push it in and it should slide off easily. I would reflow any solder joints of any parts that are heavy that could vibrate and crack any solder joints. Lead free solder sucks. Do you have an ESR meter to test the E caps. The switching power supplies are notorious for killing caps. Check the power supply rails for heavy ripple on them. The ripple could be high frequency like 100khz to 500khz. This will point to bad filter caps also. Look on line there are ton of DIY ESR meter circuits out there. I made one 8 years ago and it is my most valuable test tool. By the way when and where are the local Chicago area hamfests and radio swap meets? THANX. Looking forward to your progress on this.
Resolder power transformer, looks like the secondary connections are cracked in the video. Had similar problems with AC control boards with cracks on the heavy parts making poor contact.
Without even watching the video beyond seeing the initial flickering symptoms, and without reading any comments, as a total beginner in this field, I’m still going to say this looks like a low voltage/power supply issue. I’ve seen digital electronics (in my case, music gear) act exactly like this when voltage supply was low. It will be interesting to see if I’m correct…
My first thought was a voltage regulator, but it could be a high ESR cap in the SMPS too
Did some troubleshooting tonight. It's a much simpler circuit than I realized. It's just a liner power supply. 12.6 vac transformer, bridge rectifier, 7812 and 7805 regulators with a few caps.
The rapid pulsing is the microcontroller resetting over and over very quickly. Since I doubt it has an external reset signal, the only way it can reset due to hardware is a brown out on the power supply. I suspect that when the microcontroller boots and does the display test where all the LEDs come on at once and the buzzer beeps, this causes the voltage to drop. The microcontroller then resets and turns the LEDs off, the voltage comes back up, and the cycle repeats.
You are definitely on to something. Stayed tuned for part 2
bypass all the electronics, run fan and compresser cont. un plug when not needed
Interesting idea. Maybe I can make use of the collection bucket full sensor to shut it off.
It will freeze up solid if not let to defrost once every 30 mins or so.
@@zaprodk my unit runs 24 /7 never freezes up they are like a a/c and wont freeze ,unless they are low on freon.. then they will freeze the evap coil
@@dennisqwertyuiop they run a defrosting cycle even when you run them 24/7. You just won't notice it.
How to operate the 70 pint I turn it on and after a few minutes it shuts off . I have set it on auto 30%,40%,50,60%,70% and it shuts off I changed the settings which has humidity, cycle,timer and delay start which stay on 1 or higher fan speed has auto, high and low. Which is the best way to run this unit it has 35 pt thirsty, 50 thirstier and 70 thirstiest right now its on auto at 50% both fan speed and settings can someone help it look identical to the 50 pint on top of the unit?
Bad relay or something wrong with the drain pan sensor.
I have one just like this but it's not pulling in the water
Since it was free to start with, unless the 5v is funky I'd probably ditch it or if you can just run it full tilt by hot wiring the fan and compressor. I suppose if you could figure out which wires go to the power board you could get an arduino or something and control it with that.
It will freeze up solid if not let to defrost once every 30 mins or so.
I'm stuck at those decorative bits of plastic at 2:06. I think I just need to clean the coils but don't want to break anything. How did you get them off?
Sorry I don't remember. I think I pried them off.
chip reset via nad voltage.
It seems kinda reversed to me. Usually when cap goes bad it doesn't want to start and after the cap formes a little it startes sort of working, this seems odd. Anyway - I don't see quartz rezonator on the board, so the MCU is probably timed from some RC oscillator, so there is no indication on which speed it runs. The thing is - if it runs on 4 MHz, it needs only 2.2V for supply, if it runs on max 12MHz, it needs 4.5V. Anyway, thats just me babbling around.
The problem seems obvious, power supply is crapping out. From what I can see the power transformer is very, VERY poorly soldered so I would start by resoldering the transformer. If that doesn't help, then look into the power supply, one of those caps probably are designed to fail, usually it is the reference cap on primary side of the PSU. Sometimes it takes out the regulator too, but there it seems to be working good since it at least provide some voltage.
It is fairly primitive device, no need for schematics, you will figure it out easily. Somebody who knows that much about the hardest electronic device out there (tubes) shouldn't be stopped by simple switching PSU and one MCU :D
change all the filter caps on the power pcb
bad caps in the switch psu
These little units can be finicky I don't think it's a capacitor
Blown voltage regulator
Where's the predicta TV build :(
I've picked up three more plus spare parts. Plenty of Predicta action to come
@@bandersentv After you finish the predicta build I'd love to purchase it if you are selling it. Love to buy one before the end of summer. I want to hook it up to a DVD player to watch old black and white movies.
Sorry, but I don't think I will have one by then. I have two TVs to restore for someone else. Then not sure which Predicta to restore. That gold siesta I started on is a mess and will take quite a while to finish. The Debutante with stand I showed recently I'm going to keep - at least for a while. The Holiday I recently got is also a major project and is missing legs.
Which predicta build? He's rebuilt/repaired lots of predictas, go watch one of those series. Predicatas are boring, just a typical late 50s-early 60s series string TV set, aside from the Princess/Debutante/Siesta sets which are typical transformer sets from the same era. The only thing that makes them interesting is the styling, other then that the performance, and circuitry, is very average.
As for myself I'm hoping that he will fix up his Dumont Clifton, one of the Strombergs, the early Philcos, one of the 10'' Motorolas, the Emersons, or that Sears Silvertone set with loctal tubes in it, but it's his channel. I like it when he restores one of the more unusual sets, same with the radios.
I'm a bit tired of the Predictas too, but they are in high demand. I will tip you off that the next projects are for another client and include a 21" metal cabinet Admiral from the early 50s and a classic bakelite GE 800 "locomotive" from 1949. I think that will be an interesting project.