Diagnostic assistant needed for a Harman P68

[MrLane]

Recently I purchased a used Harman P68 that was a priced that I felt was good especially if I have to purchase parts. After bringing her home I set out to give her a good cleaning and to familiarize myself with her. All passages, fans and motors have been cleaned and oiled as able. except removal of the auger and motor. After reassembly I set in to inspect unit operations and take voltage, amp draws and ohm readings and have several issues that I could use some additional help thinking through.. I have a suspicion of what is needed but am looking for a second opinion, being that this is my first Harman Stove. Here is the info that I've gathered when placed in TEST.

The stove didn't come with a room sensor.. that will be ordered.

• Supply voltage: 122v
• Combustion Mtr: 120v @ 1.4A (Noisy plan to replace)
• Hopper door sw: Confirmed operation
• Pressure sw: Confirmed closed after start up
• Feed auger Mtr: 107v @ 4 (high 1.5 rated) will ck for binding
• Ignitor: 53 ohms only receiving 68v (checked wiring for pinch points or cuts, NONE. Also fuse on board is Good) additionally I bench tested the ignitor @ 122v it heated up to abt. 950° in 2-3 min.
• ESP Probe: Registers 1080 ohms at a room temp of 69°
• Distribution Blower Mtr: 104v @ .8A

My questions? Why is my voltage reduced at the distribution blower Mtr and auger motor. And why am I not receiving 120v to the ignitor and only 68v

 

[zrock]

umm what is the stove not doing? Have you even tried starting it and making sure everything is working?

 

[Washed-Up]

Even in test mode…all led’s coming on? The stove should cycle through all operations.

 

[ABusWrench]

The stove will run without the room temp sensor, just run it in stove temp/manual mode.

 

[Northwoodneil]

I'm not sure how the dis. blower is speed adjusted but I'm guessing it's by varying supply voltage. I do not know how they do this with an AC motor (DC is simple less voltage in less speed out) . With all that said I'm guessing your speed knob is not turned all the way up or there is a dead spot in your potentiometer. I'd try cleaning the pot and seeing what happens to your voltage as you adjust the speed knob from low to high.

 

[Northwoodneil]

Oh, I reread your original post, you've got some other things going on there.

 

[MrLane]

umm what is the stove not doing? Have you even tried starting it and making sure everything is working?

Thank you for the time to respond! I did fail to mention that the stove would not start after a full cleaning and inspection! During diagnostics i found that the Ignitor was only receiving abt. 68v of the required 120v and two motors were receiving low voltage that will ultimately damage them if left uncorrected. I have a suspicion what needs to happen but desire another perspective.

 

[MrLane]

Even in test mode…all led’s coming on? The stove should cycle through all operations.

LED's come on except for the ignitor. And when I test the supply voltage there is only 68v and I've confirmed that the pressure sw is closed! And I'm concerned about the lower than optimal voltage being supplied to two of them motors.

 

[MrLane]

LED's come on except for the ignitor. And when I test the supply voltage there is only 68v and I've confirmed that the pressure sw is closed! And I'm concerned about the lower than optimal voltage being supplied to two of them motors.

I'm not sure how the dis. blower is speed adjusted but I'm guessing it's by varying supply voltage. I do not know how they do this with an AC motor (DC is simple less voltage in less speed out) . With all that said I'm guessing your speed knob is not turned all the way up or there is a dead spot in your potentiometer. I'd try cleaning the pot and seeing what happens to your voltage as you adjust the speed knob from low to high

Oh, I reread your original post, you've got some other things going on there.

Thanks for your input.. that's one thing that I didn't do! I will pick up some electronics cleaner tomorrow and remove the circuit board and flush it out and operate the pots in the hope of flushing them as best I can and reattach ant retry the stove operation.

 

[bogieb]

Recently I purchased a used Harman P68 that was a priced that I felt was good especially if I have to purchase parts. After bringing her home I set out to give her a good cleaning and to familiarize myself with her. All passages, fans and motors have been cleaned and oiled as able. except removal of the auger and motor. After reassembly I set in to inspect unit operations and take voltage, amp draws and ohm readings and have several issues that I could use some additional help thinking through.. I have a suspicion of what is needed but am looking for a second opinion, being that this is my first Harman Stove. Here is the info that I've gathered when placed in TEST.

The stove didn't come with a room sensor.. that will be ordered.

• Supply voltage: 122v
• Combustion Mtr: 120v @ 1.4A (Noisy plan to replace)
• Hopper door sw: Confirmed operation
• Pressure sw: Confirmed closed after start up
• Feed auger Mtr: 107v @ 4 (high 1.5 rated) will ck for binding
• Ignitor: 53 ohms only receiving 68v (checked wiring for pinch points or cuts, NONE. Also fuse on board is Good) additionally I bench tested the ignitor @ 122v it heated up to abt. 950° in 2-3 min.
• ESP Probe: Registers 1080 ohms at a room temp of 69°
• Distribution Blower Mtr: 104v @ .8A

My questions? Why is my voltage reduced at the distribution blower Mtr and auger motor. And why am I not receiving 120v to the ignitor and only 68v

I am not a technician, so all of my comments are from observation of both my P-series Harmans and reading the manual.

If you have it in test, then the igniter isn't supposed to be working anyway, so not sure how it would have full voltage. Test does not give you all the running information for any of the parts, except maybe the pellet auger.

Test will drop pellets for 1 minute, say in preparation for the very first run, and run the exhaust fan (plus pulse the room blower fan real quick for an air leak check IIRC). It does not seem to be for diagnostics except it will not drop pellets if there is an air leak (thus, also a useful mode when cleaning the stove)

 

[bogieb]

Here is where the Test mode is used:

 

[zrock]

if you were talking about the blower motors if they are like mine they vary in speed so i would assume that is controlled by voltage. The stove adjusts the speed based of settings and heat.

 

[Pell]

Mr. Lane ,did you find a solution to the problem? Would be great to know what corrected it.