Harmon 52I Smoked the Fuse Tonight

[Icemanxxxv]

The stove was installed in 2016. Still running original fan and auger motors. I smoked the original board when I pinched the wires to the ignitor when replacing the burn pot last year. I replaced the board so other than that it has been trouble free. This evening on start up right after the flame ignited the stove went silent. All indicator lights were extinguished. I removed power from the stove and pulled the board. Performed a continuity check on the fuse and it was open. Looks as if my Saturday plans are shot in the arse. Time to dust if my Aviation Maintenance trouble shooting skills. My plan is to do a full inspection of the wiring, then on to isolation of components. The combustion fan has been getting noisy over the last two seasons so that is going to be my first item after wiring inspection. I'm not expecting a could not duplicate discrepency sign off for this one. I'll keep you all posted with my findings.

 

[Icemanxxxv]

The stove was installed in 2016. Still running original fan and auger motors. I smoked the original board when I pinched the wires to the ignitor when replacing the burn pot last year. I replaced the board so other than that it has been trouble free. This evening on start up right after the flame ignited the stove went silent. All indicator lights were extinguished. I removed power from the stove and pulled the board. Performed a continuity check on the fuse and it was open. Looks as if my Saturday plans are shot in the arse. Time to dust if my Aviation Maintenance trouble shooting skills. My plan is to do a full inspection of the wiring, then on to isolation of components. The combustion fan has been getting noisy over the last two seasons so that is going to be my first item after wiring inspection. I'm not expecting a could not duplicate discrepency sign off for this one. I'll keep you all posted with my findings.

Update #1
Pulled the stove on to the maintenance stand complete clean complied with. Not really required as we have less than 12 bags through nit but while its out why not.
Complied with continuty test through the 11 pin connector with vacuum switch bypassed results as follows
Feeder Motor Pin 11 and 3: 11.4ohms
Ignitor Pins 11 and 3: 48.5 ohms (since both it and feed motor run through the vacuum switch they share a ground)
Combustion Motor Pins 10-4: 5.1 ohms
Distribution Fans Pin 9-5: 14.1 ohms
Tested each circuit to ground. Nothing shorted to ground.

 

[Whitenuckler]

Update #1
Pulled the stove on to the maintenance stand complete clean complied with. Not really required as we have less than 12 bags through nit but while its out why not.
Complied with continuty test through the 11 pin connector with vacuum switch bypassed results as follows
Feeder Motor Pin 11 and 3: 11.4ohms
Ignitor Pins 11 and 3: 48.5 ohms (since both it and feed motor run through the vacuum switch they share a ground)
Combustion Motor Pins 10-4: 5.1 ohms
Distribution Fans Pin 9-5: 14.1 ohms
Tested each circuit to ground. Nothing shorted to ground.

You might be interested in my fuse panel:

Thread 'Harman P43 Fuse Panel'

Oct 5, 2025

I just finished getting things a bit more presentable. I finally broke down on bought a label machine. First time using automotive type wire tape.
I have been running it for quite a long time and the fuse size is good. I already used the switches when I did my cleaning. I had only the AC and Combustion blower switches on in test mode. I only had to add one extra set of disconnects other than what was already there. I didn't want to dig in the back to find them. I did all the work through the circuit card opening. I have some other pictures and if anyone wants more info let me know.

• Whitenuckler
• Replies: 2
• Forum: The Pellet Mill - Pellet and Multifuel Stoves

• 

If I were you, I'd make up a 120V 5A test cord and run all your circuits separately.

 

[Icemanxxxv]

Update #1
Pulled the stove on to the maintenance stand complete clean complied with. Not really required as we have less than 12 bags through nit but while its out why not.
Complied with continuty test through the 11 pin connector with vacuum switch bypassed results as follows
Feeder Motor Pin 11 and 3: 11.4ohms
Ignitor Pins 11 and 3: 48.5 ohms (since both it and feed motor run through the vacuum switch they share a ground)
Combustion Motor Pins 10-4: 5.1 ohms
Distribution Fans Pin 9-5: 14.1 ohms
Tested each circuit to ground. Nothing shorted to ground.

No signs of wiring damage. Waiting of fuses from Amazon in the morning. No body carried the ceramic I got a bunch coming. It might have been a surge or the board itself went Tango Uniform. It is an aftermarket Amazon Board.....

You might be interested in my fuse panel:

Thread 'Harman P43 Fuse Panel'

Oct 5, 2025

I just finished getting things a bit more presentable. I finally broke down on bought a label machine. First time using automotive type wire tape.
I have been running it for quite a long time and the fuse size is good. I already used the switches when I did my cleaning. I had only the AC and Combustion blower switches on in test mode. I only had to add one extra set of disconnects other than what was already there. I didn't want to dig in the back to find them. I did all the work through the circuit card opening. I have some other pictures and if anyone wants more info let me know.

• Whitenuckler
• Replies: 2
• Forum: The Pellet Mill - Pellet and Multifuel Stoves

• 

If I were you, I'd make up a 120V 5A test cord and run all your circuits separately.

See which one smokes the fuse! I'm on it!

 

[Icemanxxxv]

Fabricted the test whip. All blowers and feed motors function normal. With 48 ohms on the ignitor and it not being shorted to ground I putting my money on the aftermarket board fubar.........

 

[Icemanxxxv]

You might be interested in my fuse panel:

Thread 'Harman P43 Fuse Panel'

Oct 5, 2025

I just finished getting things a bit more presentable. I finally broke down on bought a label machine. First time using automotive type wire tape.
I have been running it for quite a long time and the fuse size is good. I already used the switches when I did my cleaning. I had only the AC and Combustion blower switches on in test mode. I only had to add one extra set of disconnects other than what was already there. I didn't want to dig in the back to find them. I did all the work through the circuit card opening. I have some other pictures and if anyone wants more info let me know.

• Whitenuckler
• Replies: 2
• Forum: The Pellet Mill - Pellet and Multifuel Stoves

• 

If I were you, I'd make up a 120V 5A test cord and run all your circuits separately.

Fabricated test whip all blower and feed motors function test normal. If I were a betting man I putting my money on the aftermarket control board being Fubar.....

 

[Whitenuckler]

Fabricted the test whip. All blowers and feed motors function normal. With 48 ohms on the ignitor and it not being shorted to ground I putting my money on the aftermarket board fubar.........

Yes 48 ohms seems good and no ground. You could have a bad board for sure. You could put 120V on the igniter too. Maybe when it heats up something changes.

 

[Whitenuckler]

You could power up your control card with the main plug off. Also, can you repair your other card? Igniter output triac?

 

[Icemanxxxv]

Yes 48 ohms seems good and no ground. You could have a bad board for sure. You could put 120V on the igniter too. Maybe when it heats up something changes.

I couldn't seem to fish the wires out of the back of the stove to hit it with a buck 20. Ive got fuses coming in the morning. I have another ignitor NIB. I'll try to fish it out tomorrow and test it on the bench. If it is bad I've got a spare.

You could power up your control card with the main plug off. Also, can you repair your other card? Igniter output triac?

I'll try that in the morning when the fuses get here. I'll have plenty on hand then. I also have the triacs on order. I'm changing all 4 of them. Should have done that last year but why do anything before you have to. I always say😁 Hopefully I'll have a running spare if this board is still good.....

 

[Icemanxxxv]

I couldn't seem to fish the wires out of the back of the stove to hit it with a buck 20. Ive got fuses coming in the morning. I have another ignitor NIB. I'll try to fish it out tomorrow and test it on the bench. If it is bad I've got a spare.

I'll try that in the morning when the fuses get here. I'll have plenty on hand then. I also have the triacs on order bI'm changing all 4 of them. Should have done that last year but why do anything before you have to. I always say😁 Hopefully I'll have a running spare if this board is still good.....

You could power up your control card with the main plug off. Also, can you repair your other card? Igniter output triac?

So your saying connect the power in and see if it lets the smoke out of the fuse? With no demand from the stove because the 11 pin is disconnected wouldn't that prevent anything from happening because nothing is being demanded from the board?

 

[Whitenuckler]

So your saying connect the power in and see if it lets the smoke out of the fuse? With no demand from the stove because the 11 pin is disconnected wouldn't that prevent anything from happening because nothing is being demanded from the board?

Sometimes if the problem is on the board itself, it will not matter if the 11 pin plug is disconnected. When you first power on an a board in off, it should just generate faults codes with the plug off. If there is a short on the board it will blow the fuse. I might use a cheap fuse for that test.
Edit - Since the 120V from the wall comes in the plug, you really can't do what I said - you would need to disconnect the hots - most should have a stab connection from the plug to the load.

 

[Whitenuckler]

I was thinking..when I power up my P43 up in off mode, it turns the comb blower on for 1 second. If your stove did the same thing, or nothing, then a shortcut would just be to power up the stove in off, or perhaps disconnect the comb blower. If you have a shorted triac, it will blow the fuse regardless.

 

[Icemanxxxv]

Update...
So while I was waiting for my fuses to arrive this morning I decided to pull the combustion fan motor (it was super loud). Cleaned it up a bit and oiled the bearings and reinstalled. Once the fuses arrived I started to tidy up the wiring and get everything ready to reinstall the board. I vacuumed out the hopper, so I could run it through a complete start cycle. Thinking that if it blew the fuse during the start cycle I wouldn't have a smoldering mess again. Installed the fuse and reconnected the board. Slid the unit into place and turned it on. Everything went well it completed the start cycle with no pellets. The combustion blower noise is essencially gone and the best news is the fuse survived. It is pretty warm for KC today so the stove is waiting for heat demand. Now I have to find the sweet spot for the Temp setting again. Fingers crossed. We'll see this evening if runs as required.

 

[Whitenuckler]

Update...
So while I was waiting for my fuses to arrive this morning I decided to pull the combustion fan motor (it was super loud). Cleaned it up a bit and oiled the bearings and reinstalled. Once the fuses arrived I started to tidy up the wiring and get everything ready to reinstall the board. I vacuumed out the hopper, so I could run it through a complete start cycle. Thinking that if it blew the fuse during the start cycle I wouldn't have a smoldering mess again. Installed the fuse and reconnected the board. Slid the unit into place and turned it on. Everything went well it completed the start cycle with no pellets. The combustion blower noise is essencially gone and the best news is the fuse survived. It is pretty warm for KC today so the stove is waiting for heat demand. Now I have to find the sweet spot for the Temp setting again. Fingers crossed. We'll see this evening if runs as required.

Sounds good. One thing about bearings - you can't re-lubricate sealed ball bearings unless they bad and the race is open. They are greased with they are made, then sealed. If they go bad, they need to be replaced. All the oil you put on the shaft will end up in the stove/motor. If the bearing is a bronze open type, then maybe. I don't think the manual calls for lubricating bearings. The cheapest motor they use is the auger motor. One side might be an open bearing on that one. Good luck

 

[Icemanxxxv]

Yeah the oil is just a band aid until after Turkey Day when I intend on changing the motor.

 

[Icemanxxxv]

Yeah the oil is just a band aid until after Turkey Day when I intend on changing the motor.

It's alive and running well. Not quite actually know what caused the malfunction. As I used to document "Cleaned connector system ops normal." It does run quieter for sure.

 

[Whitenuckler]

It's alive and running well. Not quite actually know what caused the malfunction. As I used to document "Cleaned connector system ops normal." It does run quieter for sure.

That's great. It also is good as you will be one step ahead the next time it needs a burping. Maybe when you have time you will get that other card working as a spare. Having a known good spare can make troubleshooting faster.
I am saving your ohm readings in a word doc for future reference.
It looks like the combustion fan is suspect - It may have acted up and weakened the fuse over time.

 

[Icemanxxxv]

Yeah I have triacs coming from Mouser. I'll solder them in then install the board and verify its operational. Save it for a rainy day. After the holiday I'll be purchasing a new combustion blower assembly. My plan is to disassemble the OG clean it and replace the bearings verify its operation and save it for a rainy day too.

 

[Icemanxxxv]

The stove has been operating normally for 12+ hours now. Damn angry Pixies are back in their box.

 

[iruntoo]

Yeah I have triacs coming from Mouser. I'll solder them in then install the board and verify its operational. Save it for a rainy day. After the holiday I'll be purchasing a new combustion blower assembly. My plan is to disassemble the OG clean it and replace the bearings verify its operation and save it for a rainy day too.

Can you share the part number of the Triac? Having an issue with combustion fan not shutting off. ESP probe Ohms within range

 

[Icemanxxxv]

Mine are T835-600G