Cab50 Control Box Replacement

[wyomike]

Hello and thank you in advance for your assistance. I searched the hearth.com forum but could not find this problem specifically.

I have a Heatilator Eco Cab50 pellet stove that has run well for the last 3 years. (This part may or may not be relevant to my current problem..) This year I started out with a birds nest in the chimney that the chimney sweeper pushed to the bottom and plugged the exhaust outlet. After some digging and cleaning, I removed all of the nest and the stove worked great. It ran for a month and a half before the current issue - probably 20 bags of pellets.

Came inside one day and smelled electrical smoke. I figured the Control Box had malfunctioned and called service. They took over 3 weeks to arrive. When they did, they told me the Control Box had issues. They didn't return for over 2 weeks so I bought my own OEM Control Box because 5 weeks without heat in Wyoming and having to use electric portable radiators stinks. Part numbers of the Control Box match new/old, look the same, turned the selector switch to the correct setting (2), etc. I installed the new Control Box and powered the stove up. Everything sounded good- exhaust fan came up to speed, augur dropped pellets- all seemed to be good. To install the box I had to move the stove so I powered it down, pushed the stove into position, and powered it back up. This time the exhaust fan only spun up to a low speed and no augur. I pulled the augur thinking maybe it was jammed, but it is not. When I try pushing the reset button, the exhaust fan comes up to full speed. The moment I let off the reset button, the fan slows down.

I read on hearth.com a post where someone said the system has to go through a 15 minute delay with the thermostat not calling for heat, so I've tried that (went about 20 minutes). Through that whole period, the exhaust fan spun at the slow speed.

The red power LED is not on (the one below the fuse; the fuse is good). The blue light blinks on the Control Box.

Any thoughts on where to go from here would be greatly appreciated.

Thank you.
-Michael

 

[jzm2cc]

You have an issue with thermostat, or wires on back of stove to thermostat connector, or two connectors on inside of stove on thermostat block.

If you jump across thermostat connector block outside stove, the red light should come on. If so the issue is external to stove. If no red light, check connections inside stove cabinet.

 

[wyomike]

You have an issue with thermostat, or wires on back of stove to thermostat connector, or two connectors on inside of stove on thermostat block.

If you jump across thermostat connector block outside stove, the red light should come on. If so the issue is external to stove. If no red light, check connections inside stove cabinet.

Thank you, jzm2cc. I tried jumping connector block and like you said, the red light came on and the stove is doing its thing. It's 56* in here this morning so the heat is a welcome addition. I trimmed the wires from the thermostat back an inch or so, stripped them, and reconnected them - seems to be running off the thermostat without a problem (up until the Control Box died, it always had). Sorry if I missed that in the manual.

One follow up question, if I may: could a weak connection from the thermostat have caused premature failure in the Control Box? When I pulled the thermostat wires out, part of the plastic sheath was crimped from being screwed down in the thermostat connector block. The original Control Box burned up the transformer on it. It seems like that Control Box should go for more than 3 years. I've always had the stove plugged into a surge protector and unplug it through the summer months to make sure it doesn't get electrically cooked.

Thank you again, I am much appreciative.

 

[jzm2cc]

The thermostat is basically an automatic short between the two wires when room temp drops, then it opens up connection when temperature is reached, so no it didn't cause module failure.

I haven't seen your control board obviously for damage, but I'm curious if you've checked the control board fuse including the little green pico fuse to see if they are blown (open circuit).

If a short circuit occurred on a motor circuit I could see damage to the transformer happening, along with blowing fuses.

 

[wyomike]

The thermostat is basically an automatic short between the two wires when room temp drops, then it opens up connection when temperature is reached, so no it didn't cause module failure.

I haven't seen your control board obviously for damage, but I'm curious if you've checked the control board fuse including the little green pico fuse to see if they are blown (open circuit).

If a short circuit occurred on a motor circuit I could see damage to the transformer happening, along with blowing fuses.

Thank you for your reply. That makes sense on the thermostat. I checked the little fuse on the circuit board (it's labeled below it is 800 mA). There is what looks like a fuse at F2, but I don't see any of those little pico fuses. This is the newer style board so maybe the fuse at F2 replaced those green pico fuses?

Anyway, the transformer has the tell tale signs of going bad - aside from the smell, it has that yellowish residue on top of it and one side of the transformer has bulged out a bit.

I wonder if the bird's nest made the exhaust motor pull more power, making that transformer weak and causing premature failure. Probably will never know.

Thanks so much for your help!

 

[jzm2cc]

Usually F2 is the green pico fuse, newer board as you stated. I'd be tempted to measure resistance across it (unpowered of course) to see if fuse is still good. But as you say, transformer may be cooked. Many parts are replaceable on that board quite cheaply, outside of the processor.

 

[Ssyko]

The transformer is a step down transformer and it is not connected to any motor in the stove. It reduces voltage and current from 120vac down to 5-50v ( depending on design)for the contol circuits on the board. If it fails the board will not function. The staining is probably the laquer they submerged them in to insulate and protect from corrosion.

 

[wyomike]

Usually F2 is the green pico fuse, newer board as you stated. I'd be tempted to measure resistance across it (unpowered of course) to see if fuse is still good. But as you say, transformer may be cooked. Many parts are replaceable on that board quite cheaply, outside of the processor.

Thanks, again. I'll see if I can't tinker around with that fuse and transformer and see if I can get it to work.