Motor transistors keep dying on me

[EmilFrid]

If it's a grounding issue, maybe I should just tie the reel motor control card's ground to chassis? Motor control's ground measures 0,8 ohms to chassis

 

[map2112]

Do you have a copy of all of the schematics for the unit, including the control unit and the motor control boards we could look at?

I looked in the forum for the schematics but the link was missing.

Are the 3 pairs of 100VAC transformer windings separate? If you disconnect the transformer is there any connection between the 3 sets of windings? I assume these should all be isolated from each others, both when disconnected and also when the motors are connected.

Mark

 

[EmilFrid]

@map2112 yes, they are indeed separate and don't show any continuity between each other.

I will post pics from my service manual tomorrow. Im thinking PSU, reel motor control and some more stuff. Thanks for chiming in, I appreciate that

 

[map2112]

Maybe this has been asked, but are the two transistors for the supply and take up motors mounted to a common heat sink/plate? With the transistors mounted, is there any continuity between the two transistor cases (collector) or to the heatsink?

 

[EmilFrid]

@map2112 no continuity to chassis or between the transistors. That was among the first things I checked

 

[EmilFrid]

Will work on it tonight and hopefully move forward with this