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Air Pohoda/Jablotron: does anyone have a control board?

jchwang | Posted in Mechanicals on

I have an Air Pohoda ERV with what appears to be a bad control board. Hoping someone out there has another one, or expertise to troubleshoot the thing.

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  1. Expert Member
    BILL WICHERS | | #1

    It’s doubtful you’ll find much help troubleshooting a board. Almost no one does board-level repairs anymore, everyone just swaps parts these days.

    That said, oftentimes corrosion is the problem with these boards (in general, I don’t have experience with yours specifically). Corrosion does usually one of two things:

    1: corrode pins/sockets/screws on connectors. You can clean these with a combination of a light abrasive like a scouring pad, and w product called “deoxit” which is a contact cleaner made for this purposes. Deoxit comes in different formulations for different materials, make sure to use the correct one for your application. Usually you’ll have either gold or nickel plated contacts.

    2: corrode traces (the “wires” that are the copper pathways on the circuit board). I’ve seen traces get corroded completely through. Do a close inspection of the board — both sides — and check for any open traces. If you find any, you can repair them by scraping off a little of the solder mask (the usually green protective coating on the board), tinning it a little with a soldering iron, and then carefully soldering a short piece of wire to bridge the gap. It’s best to use either tin or silver plated wire here. You can often harvest some tinned wire strands from old computer power cords, many of which use tinned copper strands in the wires, or you can buy it as “buss wire” in little rolls. Note that the harvester strands will be pretty fine wire gauge, which is often helpful for fixing boards in this way. Be very careful when soldering that you don’t bridge any nearby traces or component pins and cause a short circuit.

    Note that many electronic devices use RoHS compliant solders these days. These are “lead free” solders. If you don’t have experience working with these solders, I’d recommend sticking with the usual 60/40 leader solder which is still available in the US. Leaded solder flows more easily and is much easier to make reliable connections with if you don’t have a lot of soldering experience.

    If you have a dead component on the board, you may or may not be able to make a repair. Bad electrolytic capacitors are easy to replace, look for bulging or leaky capacitors and replace any you find. Burned resistors (look for yellow/brown discoloration) are also easily replaced. Semiconductors can be replaced IF you can find EXACT replacements, or if you have the knowledge to cross them to suitable replacements. Any custom integrated circuits or programmable parts that are bad pretty much means you need a new board as no one will sell you only those parts.


  2. MattJF | | #2

    Do you have any familiarity working with circuits? Any known event that killed it? Do you get any functionality or no response on plugging it in? There is a basic schemitic here if this is the model you have:

    The most basic thing is making sure the board is getting power.

    This looks like a pretty fancy ERV. Worse case is you can probably get the fans running and have a pretty good "dumb" ERV. There should be some cheap ECM motor speed controls available that you could wire in place of the main control board and would give you a knob to adjust speeds of each fan.

    If you want a project, it's not too bad to get an Arduino or PLC to do most of the native functionality.

  3. jchwang | | #3

    Thanks guys. Some more background info:

    The unit I have is one of the original AIr Pohoda Ultimat 240e -iERVs, so the Jablotron installation manual probably won't help.

    The ERV does initiate (i hear gates opening/closing) but then it shows a fault and doesn't respond to any commands. I tried to troubleshoot remotely with the inventor but then he soured on my electrician and Mechanical Engineer after they tried a few things and asked questions. Basically said my guys didn't know what they were doing and refused to communicate any further, despite originally promising to send us a new board from the remaining stock he had. He had his patents bought by Jablotron and last I heard, he was hired to be their lead technical guy, so I assume he is now focused just on their products.

    So my assessment of a faulty board is based on the inventor saying we should just replace the whole thing. Since that is no longer an option, I guess we have to troubleshoot or as suggested, program something from scratch. I have no experience with circuits, but assume the difficulty will be in reverse-engineering the control logic / strategy?

    P.S. We originally lost the European power cord, so had to replace with a North American one. Then we still weren't getting power to the unit and found a faulty connection inside the unit which we replaced. I don't think that damaged anything, but its possible.

    As I said, right now we get a fault which I haven't been able to diagnose.

  4. Expert Member
    BILL WICHERS | | #4

    I’d first suspect electrolytic capacitors (usually route can-like devices), especially if this unit is more than a few years old. Electrolytic capacitors have a lifetime, and they wear out. They’re also cheap and relatively easy to replace.

    The other possibility in one or not actuators has gotten gummed up and is drawing too much current, causing the unit to fault after a while as it either heats up too much or detects something is taking too long to happen.

    It’s really hard to diagnose something like this remotely, especially without even a pic. If you can post a good, clear pic of the components on that control board, I can eyeball it for you and at least see if any parts look bad visually. I’d be looking for bulging or leaking capacitors, and discoloration on anything that would mean thermal degradation. My guess is any custom programmed parts are ok from what you’ve described, so you can probably repair this unit.


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