Control Board Problems

Discussion in 'General Electronics Chat' started by TelecomFrank, Nov 19, 2011.

  1. TelecomFrank

    Thread Starter New Member

    Nov 19, 2011
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    0
    Hello! I have a problem with a circuit board controller that runs my pellet stove. I pulled the board out to inspect for problems that could be causing the issues I'm having. I found the 2 100K A PCB potentiometers that control the auger and draft fan speed to be almost completely broken off (previous owners handywork). I replaced them and I am still having the same issues.

    Here's what I know:
    1) Auger fan and draft fan work but won't work simultaneously.
    2) When I jumper the thermostat connector only the auger runs but when its not jumpered the draft fan only runs (would assume both should work on hi and low setting together).

    I am befuddled by this problem and can't seem to find a solution so I thought I'd ask for some help. Please and thank you!
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Well, it's going to be rather tough to troubleshoot remotely without so much as some good photos of the board, and preferably a schematic.

    Even a manufacturer and model number would be most helpful.

    Without that kind of information, we're kind of stabbing in the dark.
     
  3. TelecomFrank

    Thread Starter New Member

    Nov 19, 2011
    3
    0
    Sorry, shoulda figured you need atleast a pic. The company that made this stove has long since gone out of business and the possibility of getting schematics is almost nil. Maybe you know a source. Pictures attached below. Manufacturer: Sweet Home Model: PFA 2000
     
  4. SgtWookie

    Expert

    Jul 17, 2007
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    Well, Sweet Home might be gone, but it appears that the board maker is still around:

    Ortech Industries Inc
    1982 Northeast 25th Avenue Suite 5
    Hillsboro, OR 97124
    Ortech Industries Inc is a business dealing in the Electronic Equipment & Supplies industry. Ortech Industries Inc is located in Hillsboro, OR on 1982 Northeast 25th Avenue Suite 5.

    Ortech Industries Inc telephone number is
    (503) 640-1607.

    Aloha and Hillsboro are only about 8 miles apart; seems like they moved since your board was made.

    You might give them a call and see if they happen to have a schematic they'd send you.
     
  5. SgtWookie

    Expert

    Jul 17, 2007
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    1,728
    The TO-220 packaged devices labeled Q4010L5 are 400V 10A TRIACs. Digikey stocks them:
    http://parts.digikey.com/1/parts/992755-triac-isolate-10a-400v-220ab-q4010l5.html
    The XR494 appears to be a copy of the Texas Instruments TI494.

    Are those two blue trimmer pots on the left what you replaced the 100k pots with?
    Those are only 500 Ohms! I have no idea how they are generating the low voltage power in that circuit, but changing a couple of pots from 100k to 500 Ohms would certainly load it down. You need to order some potentiometers that are in the right range of resistance.
     
  6. TelecomFrank

    Thread Starter New Member

    Nov 19, 2011
    3
    0
    I'll call tomorrow to see if I can order a replacement or atleast get a schematic. Is it a possibility one of the Q4010L5 400V 10A TRIACs are damaged causing the problems I'm having? Its what I believe intermittantly turns on the auger motor. It runs intermittantly for a fraction of a second when its turned on while it should run for about 3-6 seconds depending on the setting. I'll post tomorrow with my findings.

    Also, the potentiometers I replaced are on the top backside out of view. They are controlled by the exterior knobs.
     
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