Repair thermoelectric cooler

Discussion in 'Technical Repair' started by wayneh, Sep 23, 2014.

  1. wayneh

    Thread Starter Expert

    Sep 9, 2010
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    I'd avoid a slow-blo. Even a regular fuse takes far longer to blow than you might expect. The main current-drawing device in these things is the peltier and as far as I know there is no surge current when one starts up. The fan would see a surge at startup but it's a much lower current than the peltier (100mA versus 5A).

    Is there no indication on the original fuse about what type it is?
     
  2. MaCheFai

    New Member

    May 10, 2017
    11
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    Unfortunately not.
     
  3. penguinologist

    New Member

    Jun 21, 2017
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    I just wanted to let you all know that this one thread has allowed me to fix a $20 broken wine cooler off Craigslist, resulting in a perfectly happy new refreshment center for the office. Thank you guys!
     
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  4. wayneh

    Thread Starter Expert

    Sep 9, 2010
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    Care to share what your repair required?
     
  5. penguinologist

    New Member

    Jun 21, 2017
    2
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    Sure. I ended up replacing all the caps except one of the 22uF25V capacitors (Digikey forgot to send it), as well as the NPN transistors. Likely the capacitor messed up the npn because it was getting some power, but not enough to start the fan. Oh, and there were a few cold-solder issues as well but those were easy to fix.

    FWIW, my board was a FX-101 pcb, and my wine cooler is an 18-bottle Wine Enthusiast cooler with dual-zone temperature control. Total cost of parts was $11.37 + 3.93 shipping. I ordered the Skottky array as well but I'll be returning that since the size they sent is much too large to fit the PCB.
     
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  6. SydB

    New Member

    Nov 29, 2016
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    After I replaced one of the controllers in my wine fridge, I discovered it was not getting cold enough. After some temperature data logging inside and out close to the fans (fans connected and disconnected), I concluded the peltier module on the other controller was not working well enough. The outside was getting hot but the inside was not getting cool. The peltier module was drawing about 3A instead of what I think should be closer to about 4A at abotu 12V. So, just replaced it with another whole module I found on ebay which appears to fit ok (amazingly). No idea what the NTC thermister value should be (because one original was reading about 10k and the other about 1.5k!) but it seems to work - possibly if the fan fails it might overheat now. It might actually have been the NTC at fault since there was such a difference between both modules. I will investigate. I need to make sure the condensation is going to go where it should now, too, since the heatsink arrangement is substantially different.

    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) - check out the bling with the PC fan I have had lying around for ages (I am thankful for cable ties):

    Img_1093.jpg

    Temperature-time plot of temp sensors on the inside (in), outside (out), top and bottom (bot) modules, showing top module not doing its job but you wouldn't have been able to tell easily just from feeling the outside heatsink. I manually disconnected the fans to begin with in order to emphasise any peltier defect, then connected them after about 20mins:
    Image1.gif
     
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  7. N_Jay

    New Member

    Jul 21, 2017
    15
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    You guys are great.
    My wine fridge just died and I find the correct board is NLA.
    My symptoms are a lot like the others with no start, but (near) normal start with the peltier disconnected from the bad controller board.
    It is a dual zone unit with two boards. As a test I connected the peltier that was hooked to the bad board to the good board and verified that it worked.
    Given the red and green LEDs come on the bad board when the peltier is disconnected, what is the likelihood that it is just bad caps and no failed semis?
    My thought is a blown semi or fuse would either show as no power even with the peltier disconnected.
    Thoughts before I order the parts and dig through the basement to find my soldering station. (Been out of "hands" on electronics for a while)
     
  8. wayneh

    Thread Starter Expert

    Sep 9, 2010
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    High. Replacing caps has been all it takes for many folks to get running again. That's no guarantee, but it's a place to start.
    A blown fuse would, yes, but a blown power transistor wouldn't necessarily.
     
  9. N11778

    Member

    Dec 4, 2015
    98
    27
    Another use for a wine cooler, Butter cooler.
    It's to hot in the Arizona desert to keep butter in the room.
    We set the Air conditioning to 88 so the butter is too soft.
    Anyone know of a very small single bottle wine cooler / butter cooler on the market?
    Say about the size of 3 pounds of butter? I don't have much room.
    Oh, and after changing several capacitors and the driver transistors mine is still working.
    Sparky
     
  10. wayneh

    Thread Starter Expert

    Sep 9, 2010
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    No, but the small ones for use in a car might work. Just give it power from an old laptop power brick. I think if it's designed to handle a car's power supply, it can handle ~19V out of the brick. Or you could drop the voltage with, say, 6 diodes in series. Of course you could also just buy a 12V AC adapter.
     
  11. N_Jay

    New Member

    Jul 21, 2017
    15
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    One of those silly desktop 6 pack coolers that looks like an old Coke machine.
     
  12. IMP002017

    Member

    Jan 28, 2017
    187
    30
    Don't know how well one of the 4 bottle coolers would work. They are under 100 I think even less then 75. They are called Vertical Mini Wine Cooler. Gave one to my Sister in law and she loves it.
     
  13. K6216

    New Member

    Jul 23, 2017
    7
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    Hey, I picked up one of these emerson coolers for $15 USD, bad supply. Has the same Fx101. I replaced all caps first, and measured the ESR on them. Some were a bit high, but C8 (47uf) was over 80 ohms! D6/C8 integrate small start pulses from the power schottkys to provide VCC to the TL494 oscillator/regulator. C8 failure means no start up of the primary switches. Anyway, no bad active devices. TEC started up and power is 70W, right on target. Now cooling is 64F on way to 54F.

    OAN, if no one has tried google translate on that Italian site with the schematics, it works great and the tutorial is worth following.
     
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  14. wayneh

    Thread Starter Expert

    Sep 9, 2010
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    Are you referring to a link in this thread somewhere?
     
  15. K6216

    New Member

    Jul 23, 2017
    7
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  16. davideather

    Member

    Dec 12, 2016
    33
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  17. SydB

    New Member

    Nov 29, 2016
    8
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    Not sure if that was a bump or what...

    Sounds like a failed TEC. Resistance is more than that in my experience. Yes, a fixed 12V power supply is an option but it has no feedback control. So long as you do not want accurate temperature and just want max cooling then go for it, but there is no control, and you will likely need a 6A supply or so. If you want less cooling, maybe try the 5V output if using a PC supply; the current capability is typically much more than the 12V rail and cooling power should be less. Will 5V work; not sure? You could even try two +5V supplies connected in series to give +10V. It depends what you have lying around, really. TECs are very cheap on ebay (not sure of quality) if you want to play with replacing it; you will also need thermal compound and have lots of tissues to hand - it gets everywhere.
     
  18. N_Jay

    New Member

    Jul 21, 2017
    15
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    A quick THANK YOU to the people here.
    Your advice and a handful of capacitors from Mouser and I will have chilled wine by tomorrow.
     
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  19. K6216

    New Member

    Jul 23, 2017
    7
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    I think if u run the TEC hard from 12vdc u run the risk of freezing the internal heat sink. Then , like a fridge with bad defroster, u get no more cooling. The NTC plug on the PCB is on the cold side. It turns off the power of it thinks the cold side might freeze.
     
  20. davideather

    Member

    Dec 12, 2016
    33
    3
    ????? is a thermostat and a relay so hard to conceive and rig up??????
     
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