SUCCESS STORIES: Repair thermoelectric cooler

K6216

Joined Jul 23, 2017
17
????? is a thermostat and a relay so hard to conceive and rig up??????
Well, it's not that you cant implement an on/off controller, but where are you going to measure the temperature? If you measure the air space temp or the actual temp of a bottle or something and your relative humidity is above 20% I could almost guarantee you will condense and freeze up the cold head sink. And you wont know when that happens. The power supply and NTC thermistor implement a sort of reverse heat flow defroster.

These TEC power supplies are really an interesting design (except for the quality of the caps...) There are really 3 kinds of power being created. (See schematics referenced in #116) When the TEC 12V is OFF the primary circuits still deliver 10-11.5V via D5/CA1 to power the 8V linear regulator powering the display controls. IC U1 is a PWM controller for delivering high current via the primary switches, DD1 & LOUT. U2A is a comparator with hysteresis to defrost the cold sink. U2B is an amp with a gain of 15-20dB on the inside NTC thermistor. The amp outputs are wire-ORed by D201 & DA1 to control the PWM. So long as the defrost comparator is OFF, the temperature controller U2B will supply full 12.7VDC power until nearing the set point temperature. Once there, U2B will begin to modulate the TEC voltage in very small increments. Typically the TEC voltage will drop to 6-8V or lower depending on the humidity. The fans slow down and the whole unit gets much quieter. Periodically U2A will over-ride the wired-OR and shut down the TEC. This allows some heat from the HOT side to warm the cold side and melt any ice.

So, in spite of these supplies having crappy capacitors an dying after a few years, the design is rather elegant I think. They have thought of the problems of noise, humidity and efficiency and price. Too bad no one told them about bad-caps.....

If you implement an ON/OFF controller from like an AC unit, you may not have control over hysteresis. You could use a PID controller, but seems over kill and the TEC will still freeze.
 

K6216

Joined Jul 23, 2017
17
[soon the fuse blew again and a puff of smoke rose off the PCB !!]
Did you replace the primary or secondary side fuse? Your TEC is bad if your measurement is correct, and likely the smoke was released from resistors or diodes around T6 &T7 in the primary. These TECs are 12.7V @5-6A, or about 2.5ohms. Use a bench supply in current limit mode to test the isolated TEC. Set the compliance voltage to 12 and current limit to 1A. The TEC should pull the supply to about 2.5V. If much lower, TEC is bad.
Start raising current. If TEC is good you should get to 5A and ~12V. Don't leave TEC connected continuously. You will over heat and damage it, but if you have removed it from the frig, you should feel the hot/cold sides.

You can fix this supply rather cheaply. Get the schematics from link in #116. While #116 is a different PCB layout, it is very identical electrically and almost all component markings are the same. But first, plan on replacing ALL of the eCAPs. Look for burnt traces, fried resistors, then test the switching transistors, diodes and schottkys.

Come back and tell up what you find.
 
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SydB

Joined Nov 29, 2016
8
I hadn't realised about the defrost action. I had assumed the TEC NTC action was being used as a fail safe for overheating but, you are right, it is the other way around by the look of it as it pushes the control the same way as the temperature control NTC. Thanks for the explanation @K6216! Now I think about it, that makes sense, since the TEC I took apart had its NTC on the cold side if I remember correctly.
 

K6216

Joined Jul 23, 2017
17
@SydB
Yes, I made the same erroneous assumption when I first opened the fridge and looked at the schematic. Once I fixed the supply mine was cycling full on full off and never got to regulating. I thought it was overheating because I mis-read the U2A NTC comparator operation. I removed and disassembled the TEC module with the help of YouTube. Wait a minute, the NTC is on the cold side. Duh... Its for defrosting. The thermal paste on the TEC was hard and dry. 91% alcohol to clean and new paste in 5 minutes. Reassembled and care taken to tighten just enough. Took 4-5 hrs to get to regulation but no on/off behavior. Once regulating, it made 4-6V up & down motion in little 200mv staircase steps. That must be part of the TL494 behavior. Once at 54F I could catch it running the defrost cycle for a few minutes. (I had the TEC 12V running a strip chart recorder continuously.) It is satisfying to understand the how and why of home appliances.

Now I could talk about dishwasher turbidity sensor malfunctions, but that's for another thread!
 

N_Jay

Joined Jul 21, 2017
15
Just for the heck of it, I took all the old caps and tested them with a Uni-Trend 210E.
Found only one that was bad. It was one of the 47uF 25Volt parts.

It was not a little off. It was dead. It did not show as any steady capacitance in the test, and showed near open resistance.

Before I replace all the capacitors in the other board, I am going to check them to see if the UT210E can read the capacitance in circuit.

Wondering if it is still best just to replace them all, since they are all the same age (Cooler was 8 years old)
 

K6216

Joined Jul 23, 2017
17
@N_Jay
Was it C8 on the schematic? That may be a recurring theme. Maybe C8 is the main failure point. My C8 had ESR=80. But many others were several ohms which is too high.
 

N_Jay

Joined Jul 21, 2017
15
I really don't know.
I just tossed them in the bag as I pulled them out and replaced them.
I did take each one up one voltage rating just incase it was because they were being used at the margin.
 

drewb0y

Joined Aug 14, 2017
1
So my wine fridge is starting to look like Trigger's broom (3 out of 4 fans replaced, 1 out of 2 controllers replaced, 1 out of 2 cooler modules replaced, all with non-original replacements, and I think I had to change a cap on the little temperature board ages ago, too)
I had to look up the Trigger's Broom reference. Can't believe I haven't seen that before. Now I have a new show to find and watch! For those that also do not know this, look here - http://foolsandhorses.weebly.com/triggers-broom.html and watch here

I just picked up a Wine Enthusiast 6 bottle cooler from the side of the road that someone threw out. Pretty much the same action as everyone else, if you disconnect the Peltier, it powers up as normal, well as normal as could be expected with bad caps. Ordered new parts from Mouser, mostly 5000 hour caps, so should be better than before. Also the article in Portuguese from post #36 was very helpful. (Translated with google translate here )
 
Hi everyone,

I have my wine cooler but as soon as I put a new fuse, it blow immediately.

I found that 2 parts burned but for one i'm not able to know what is it.

Can you help me ?

Thank you !

Pierre-Olivier
 

Attachments

MrAl

Joined Jun 17, 2014
11,396
Hi everyone,

I have my wine cooler but as soon as I put a new fuse, it blow immediately.

I found that 2 parts burned but for one i'm not able to know what is it.

Can you help me ?

Thank you !

Pierre-Olivier
You should start your own thread for this.
 

Thread Starter

wayneh

Joined Sep 9, 2010
17,496
Hi everyone,

I have my wine cooler but as soon as I put a new fuse, it blow immediately.

I found that 2 parts burned but for one i'm not able to know what is it.

Can you help me ?

Thank you !

Pierre-Olivier
I see one part in the photo. It appears to be a capacitor but it could also be a varistor, a MOV. They often fail exactly the way that one looks. That's their job.

Where on the board did it come from? You might be able to tell from the schematics in this thread what the function of that part was.

You probably need to replace the electrolytic capacitors, and possibly the power transistors that may have also failed.
 

SydB

Joined Nov 29, 2016
8
The component is in series with the mains feed. It is marked as RTC on the board (unhelpful). However, I have had an inspection. It measures about 5ohm at room temperature and decreases with increasing temperature. Therefore, it is an NTC thermistor there to limit the inrush current, it has a (relative) high value when at room temperature, then it heats up from the current and the value goes lower. I doubt if an exact replacement is necessary; just get something that roughly does the same job (5ohm at room temp, maybe 5A current, same diameter). Lookup inrush current limiter thermistor e.g. 5D-11:
http://www.ebay.co.uk/itm/2x-NTC-5D...717327?hash=item41ccf894cf:g:xoEAAOSwRgJXi421
It could be the component used is exactly this: 005 = 5ohm, 04 = 4A. I don't know though.
 

rogsaac

Joined Sep 5, 2017
1
Finally, I got it!

As other said in this forum I ended up replacing all the caps. Not that I wanted but that was the only thing that worked. Now lets get to the long story.

I initially replaced the 120mF/200v and tested the board. Nothing. Still dead with cooling plate, working fine without at start and fine again when connected while working.

Then I replaced all the caps on the high voltage area all the way to the heat sink that separates the board in 2 areas, the one with a Schottky rectifier STPS2045CT on it for no avail.

Next was Schottky's rectifier turn to be replaced. I was quite confident about it but it turned out not to be the culprit.

Fourth step was the big cap, 2200mF to be replaced, again with no results. At this point I got tired of replacing and testing the board and I just replaced all the remaining caps, all small values, and than give it another try. BINGO! It started just fine and everything worked fine after that without any hiccups.

Below I attached a picture of all the staff I replaced as well as the schematic I used, copyright to a Brazilian guy, link included a few posts ago.
There is also a picture of the board, specially the low voltage part where the problem was, just to give you an idea about what I was talking about.

I also included a few details about what I ordered from Mouser.com, no affiliation, no advertising or profit here (I wish...) but this guys are from Texas and they were the cheapest and the fastest, only $4.99 for USPS shipping and that's not all I bought from them, there was a few other items in the box.

Beside those already mentioned I also replaced the display since the second digit was almost completely out.
That was a huge pain since I could not find the same display anywhere on the Internet. The original display was blue, common anode, 10 pins (only 9 used) HGA4023HB-C.
The only option I was able to find, also blue in color, common anode, with Pin 10 common anode for the first digit and Pin 5 common anode for the second digit was the one from Mauser.com, DA03-11PBWA/A.
Anyway, there are some issues with this display.
-First, the display is slightly smaller in size, including the digits. Overall it's not that much of a difference so I ignored.
-Second, except for Pin 5 and Pin 10, the common anodes, all the other pins differ. For that I had to run a bunch of wires from the new display pins to the corresponding pins on the board.

Overall an easy job if not for the display. To fix all the issues I spent around $15 and quite a few days to research for the schematic, display, possible issues and so on.
Hopefully this will help everyone to save some money and specially time, a luxury I have less and less.



View attachment 93458






===================================
Mouser #: 604-DA03-11PBWA/A

Mfr. #: DA03-11PBWA/A
Desc.: LED Displays & AccessoriesBlue diffused 2 Digit

1 $5.47 $5.47
===================================
Mouser #: 511-STPS2045CT

Mfr. #: STPS2045CT
Desc.: Schottky Diodes & Rectifiers2X10 Amp 45 Volt

1 $1.21 $1.21
===================================
Mouser #: 647-UVY1E222MHD

Mfr. #: UVY1E222MHD
Desc.: Aluminum Electrolytic Capacitors - Leaded25volts 2200uF 12.5x25 20% 5LS

1 $0.67 $0.67
===================================
Mouser #: 647-UVK1H220MDD

Mfr. #: UVK1H220MDD
Desc.: Aluminum Electrolytic Capacitors - Leaded50volts 22uF 5x11 20% 2LS

2 $0.10 $0.20
===================================
Mouser #: 140-REA470M1HBK0611P

Mfr. #: REA470M1HBK-0611P
Desc.: Aluminum Electrolytic Capacitors - Leaded50V 47uF 20% 6.3x11mm

4 $0.09 $0.36
===================================
Mouser #: 140-SEA1R0M1HBK0407

Mfr. #: SEA010M1HBK-0407P
Desc.: Aluminum Electrolytic Capacitors - Leaded50V 1.0uF 20% 4X7mm

3 $0.09 $0.27
===================================
Mouser #: 140-RGA4R7M1HBK0511G

Mfr. #: RGA4R7M1HBK-0511G
Desc.: Aluminum Electrolytic Capacitors - Leaded50V 4.7uF 105C 5x11mm

4 $0.08 $0.32
===================================
Mouser #: 661-EKXJ201ELL121MK3

Mfr. #: EKXJ201ELL121MK30S
Desc.: Aluminum Electrolytic Capacitors - Leaded120uF 200Volts

2 $1.48 $2.96

===================================




View attachment 93454 View attachment 93455 View attachment 93456
Hi: Thanks for this informative post. I had a wine cooler with the exact board and the same problem. From your experience I changed the 4 47uf capacitors on the DC side of the board. Bingo again! Starts and works properly. One of the 4 was open when checked on the capacitor meter after removal. I do not know which one it was from the board.
 

hueypic

Joined Sep 12, 2017
9
Howdy! New to the forum...
And I have to admit, more than just a little disappointed!

I have a EdgeStar model TWR182ESS wine cooler, 18 bottle, 2 zone. (all those details are for the google crawlers)
Mine has 10.5v FX-101 TEC controllers (PCB90829F1).

My indications:
  • Display blank or blanks after a few hours
  • Red and green LED VERY dim
  • Interior fan running, one external (lower) turning slowly
  • If I disconnect the TEC and reset (unplug/plug 120V) it would start up, good green and red LEDs
  • Reconnect TEC and would run but dies sometime later (over night when I couldn't diagnose more).
I didn't really check any voltages. I knew in general that it was putting out the 10.5v, but not enough amperage to run the TEC.
So, after reading a lot here, I went out to MicroCenter at lunch and bought a huge pile of caps, whatever was needed to replace everything on two power supplies (they were missing a couple in stock). I got home and pulled one of the PS. I replaced only C8 on that board (DC side), reinstalled, and everything turned on fine. I could be a little paranoid, but the LEDs on the other PS may be just a LITTLE dimmer than the repaired one, but I am going to let it go. (I'm disappointed because it was so easy!)

Thinking back, it MAY be that the other PS may have had good LEDs when I disconnected the TEC on the repaired one, but I cant be sure. It seems I kind of had this thought in the back of my mind that the one I repaired seemed to pull so much that it dragged everything down, but I never did any swapping of parts to check.

So, it took me all of about 10-15 minutes to desolder and replace the 47uF C8 cap. Yes, I am giving Murphy the finger and (for now) proclaiming some success! Thanks to K6216 who may have led me down this path. I would have to tell someone, if you have the above indications, start and try C8 first. Yes, the others may go, but mine is a few years old and I let the filters get clogged. I'll do better and see how long it goes.

Now I have a big pile of caps ($16 worth) to go in the parts drawer.... But I came away with a couple Pi Zeros w/ WIFI ($8/ea) that I had my eye on (see my github https://github.com/brownleeb/skybar_one_resurrection), and I did resist the arduino mini for $5/ea (it was 5v and needed FDDI interface that I didnt want to get right then and there).

Thanks to all! I'll report back on my success or lack thereof......
 

hueypic

Joined Sep 12, 2017
9
Ran out of time to edit my post.
Getting 10.5v with full load on both PS.
Same thing as above on removed cap, a few nF capacitance and open resistance.
 
You guys rock! I have a EdgeStar TWR215ESSDLX, dual zone fridge. The power supply layout is fairly different from the FX101, but the schematic appears to be identical (component names different, values the same). Similar symptoms: no LEDs or power w/ TEC connected, LEDs illuminate with it disconnected (though some cracking/arcing noises). Replaced all the caps, and its working 100% again. Thanks for everyone taking the time to post about this.
 

hueypic

Joined Sep 12, 2017
9
Especially with a switched power supply.
As mentioned above, I also have a couple Skybar wine dispensers that have crapped out. I got one working using a raspberry pi. However, the power supply on it seemed to stop working (they dont seem to like not having a load).
One of the caps was a little bulged out on top. There were two 1000 mf caps in series that I replaced with a 2200 mf I had left over from the wine cooler, and it fired right up. Maybe some others will go bad down the road, but its just a power supply....
I was quite happy to have applied what I learned here!
And my fridge is STILL running, only having to replace that single cap that seemed to be the central point of failure. Since the basic design of a SMPS hasnt changed, I'm kind of assuming there is a weak point that can be found without changing ALL of the caps out, but for now, it seems the biggest weak point is cheap Chinese caps.
 
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