Another MC-60 issue

Discussion in 'The Projects Forum' started by ECCsimmons, Apr 8, 2013.

  1. ECCsimmons

    Thread Starter New Member

    Apr 6, 2013
    10
    0
    Hey guys, first time caller long time listener. Thanks for all the help with schematics and advice about this MC60 controller in the past. I had this current one working just fine a week ago and I really stupidly, and unknowingly, dropped a washer on/around R55 thru R37 area. Plugged it in to test my pulley system and SPARK!! Yes, I'm that stupid...

    Now I get 12+, SPD CNTL, and SCR TRIG on solid with power, yet no motor movement with speed adjustment. Actually the SCR TRIG stays solid it just gets very dim when I adjust the speed. The CUR LIM light is also very, very dim.

    I have already unmounted and tested all resistors in the area, only one had gone bad and have replaced. The IC at U1 was very suspect with a small black spot on the GND leg, so I just replaced it for a couple bucks to no avail. I then proceeded to test Q2 and Q3 with 9vdc and a fan. Both ran with short to gate and closed without so they're fine. D1, D2, D12... all good. Yet still no movement from the motor.

    Finally I got some movement out of the motor when I took some advice and shorted the "SCR TRIG" LED with a piece of wire. As soon as I plugged the board in, the motor jumped into action at full speed. No adjustment of the POT made a difference. So I suspected the LED going bad. I removed the SPD CNTL LED and put it into the SCR TRIG spot and shorted the SPD CNTL LED out. Then I got nothing again? So I'm pretty sure the LED isn't the main issue.

    So now no matter what I try the only way I can get the motor to run is by shorting the SCR TRIG LED... and it'll only run at full speed.

    I tried to test the optoisolator LED, and it seemed to be fine. I'm not an expert though so I couldn't say positively. Should this be the next replacement or should I be looking more closely at the speed control POT?

    Thanks for any advice.
     
  2. ECCsimmons

    Thread Starter New Member

    Apr 6, 2013
    10
    0
    Nvm.. pulled speed POT and with SCR TRIG jumped it still full speed start. Going to try replacing opto unless I hear other suggestions.

    any readily available alternatives to MOC3052, or should I just digikey it?
     
    Last edited: Apr 8, 2013
  3. ECCsimmons

    Thread Starter New Member

    Apr 6, 2013
    10
    0
    Tested MOC3052 with Empirical method (i used ~270ohm) from here: http://www.antimath.info/electro/how-to-test-an-optocoupler/

    and I get "OL" with any DC voltage applied to LED side. I even tried measuring 4-6 instead of 4-5 just out of curiosity, but still OL for all voltages applied.

    Any other methods to test these things before I go and start the shipping process?
     
  4. sheldons

    Active Member

    Oct 26, 2011
    616
    101
    have you got a schematic so we can have a look see what might have failed.....
     
  5. ECCsimmons

    Thread Starter New Member

    Apr 6, 2013
    10
    0
    There are a few schematics on here for the mc60 motor controller.. ill attach when I get to my PC at home tho.
     
  6. ECCsimmons

    Thread Starter New Member

    Apr 6, 2013
    10
    0
    Sorry just realized I had one on here. Attached.

    * It's shorting D6 that allows the motor to actually come on. It's just full speed at start with no speed control is the problem at that point. I've replaced D6 with a good LED and it won't even do that though, the LED stays solid until I move the SPD CNTL POT, which case it dims to an almost nothing and never any motor movement.
     
  7. ECCsimmons

    Thread Starter New Member

    Apr 6, 2013
    10
    0
    Well no luck. Figured I'd order the Opto from Digikey for a shot in the dark... came today and no dice.

    Same results, SRC TRIG is solid and no power to motor. Then when I short SRC TRIG(D6) I get full speed motor on power, no speed control.

    Stuck!

    Going to check out some more later when I get time, but really just kicking myself in the a$$ for dropping that washer lol.
     
  8. ECCsimmons

    Thread Starter New Member

    Apr 6, 2013
    10
    0
    Still nothing. I've been testing everything I can think of, and just can't get any blinking of the LEDS to signal I'm even getting PWM.


    Help would be awesome..
     
  9. ECCsimmons

    Thread Starter New Member

    Apr 6, 2013
    10
    0
    Bump...

    Lost in the dark.
     
  10. ECCsimmons

    Thread Starter New Member

    Apr 6, 2013
    10
    0
    very disappointing with the amount feedback in this forum(or lack there of).

    5 Days of posting, schematic, clearly stated issues... yet only one statement asking for a schematic....
     
  11. Meixner

    Member

    Sep 26, 2011
    116
    21
    Well the circuit is pretty complex and also hard to read, so it's difficult to come up with suggestions. Have you replaced both U1 and U2 ? If so I would start replaceing transistors.
     
Loading...