Harman P38 shut down

[park4019]

Hi, need help with my Harman P38. Was running fine, then just shut down. It was as if we had a power failure. Control panel, only has blower control, & feed rate switch's. Took about 1 hour, before the stove was cool enough to check out. I gave the stove a thorough cleaning, especially the exhaust sensor. Still nothing.
By passed the vacuum control, nothing. Checked the internal fuse, ok. Is there a way to test the main circuit board [mother board] ?

Thanks park4019

 

[jzm2cc]

Does the exhaust motor run at all? Without this turning and creating a vacuum it won't run auger.

Could be seized motor bearings and trying to spin fan by hand will confrm this, or try plugging it into 115v directly if it spins freely but isn't running to see if it's a board or motor problem.

 

[park4019]

Does the exhaust motor run at all? Without this turning and creating a vacuum it won't run auger.

Could be seized motor bearings and trying to spin fan by hand will confrm this, or try plugging it into 115v directly if it spins freely but isn't running to see if it's a board or motor problem.

None of the motors work, when I turn the feed switch. Yesterday, I connected the vacuum control wires together, with a paper clip, to bypass the control. Nothing happened. This morning, I removed the 5amp fuse, from the circuit board; it looked & tested ok. I rigged up a jumper cable, to again connect the vacuum switch wiring, & will check it this am. The exhaust motor [ combustion motor] turns ok; while cleaning the stove, I was able to spin the fan, to clean it. Can't pull the circuit board very far out, because of the wiring. I have a wiring diagram, & I did notice some of the wiring, from motors, is not placed as shown on the diagram. Some of the hot [black] wires are attached to the neutral [white], terminals. But that's the way the stove has always been, at least 15yrs.

Thanks for the quick reply: park4019

 

[jzm2cc]

Hmmm. Back. To the top.

Will outlet power other appliances ok?
Jumpered vacuum switch? Yes
Measured for voltage across exhaust motor terminals?
Fuse ok? Yes
Have you tried turning on/off potentiometer through the full range of travel a few times to clean contacts?
Try powering exhaust directly with power jumper cord and see what happens.

 

[gfreek]

Hmmm. Back. To the top.

Will outlet power other appliances ok?
Jumpered vacuum switch? Yes
Measured for voltage across exhaust motor terminals?
Fuse ok? Yes
Have you tried turning on/off potentiometer through the full range of travel a few times to clean contacts?
Try powering exhaust directly with power jumper cord and see what happens.

. As stated above,test exhaust motor by wiring it directly to an outlet.. Only way to test the board is with another "good" board. The 2 knob board is obsolete and is replaced with an updated 3 knob kit..$$$$

 

[jzm2cc]

The 50K potentiometers are easy to replace, but i wouldn't do that until further investigation. You might have. A dead spot on one so try starting stove in another location.

 

[park4019]

Hmmm. Back. To the top.

Will outlet power other appliances ok?
Jumpered vacuum switch? Yes
Measured for voltage across exhaust motor terminals?
Fuse ok? Yes
Have you tried turning on/off potentiometer through the full range of travel a few times to clean contacts?
Try powering exhaust directly with power jumper cord and see what happens.

Wall outlet, is OK, powered up the exhaust [combustion] motor with same outlet. Jumped vacuum switch, with cable with HD crimp on terminals, exhaust motor won't run. NO voltage across the connections on back of terminal board, with terminals pulled slightly off. Removed fuse & tested, OK. Turned pot, may times. Tested continuity across terminals, ok with meter a 1/2 setting. As mentioned, I ran the exhaust [combustion], motor with jumper cable, to the outlet that powers the stove. Motor ran fine.

Thanks, park4019