CIRCUIT BOARD HELP....PLEASE

First off, tha capacitor is part of the electrocoupler firing circuit and is not needed for anything else.

Step 1 is simply cut the leads of the original capacitor to make it open circuit.

Test the board, If the board works fine without the capacitor and since many people never use o even read the manual to go through the sequence of firing the couplers, you could just leave that part out. In fact, on some boards used in units without electrocouplers, there is a line on that circuit board and they just cut that entire section off.

You can replace the capacitor and then attempt to fire an electrocoupler if you truly want to fix it for full function. But I would test first to see if the diode had failed.

From the looks of it, this may have been a built in or dented defect in the capacitor and just burned through the side of the can. That said, again, in theory, that condition of the capacitor in full short internally, put huge short circuit current through the charging circuit of the capacitor and may have killed it. If you feed the new cap with AC instead of DC (because of a failed diode) that could get ugly.

Thank you Vernon......you learn something new every day!!

I thought this capacitor was the one that gave trouble by expanding and bulging at its end, and has been mentioned so many times before on the forum.

I will follow you advice and see what happens.

Thank you again......Peter  (Buco Australia)

Most likely that cap is good.  It looks like something on the top board burned and damaged that. G

Thanks for the reply GGG.

Yeh......I have replaced the cap with the new one, but have not tested the board to see if it is working.

You are probably right in that the original problem may have been with the top board.

I was not able to get this top board or bottom board for that matter to work in my "test mule" PS1 Rail King C.S.X . SD60M Diesel (30-2116-1).

I tried each board individually with the matching good board in this loco.....problem bottom board with good CSX top board, and then good CSX bottom board with problem top board. That is the way I was able to determine that both boards were bad and to be relegated to the "junk box".

Question: The older/original QSI reverse boards - Proto-DCRU's (I have a number of these older boards I use to transplant into conversions when I remove the broken AC armature motors in my Swiss Buco loco's, and replace them with modern Maxon DC can motors) can be bench tested to see if the reverse relays are working properly.

Can I bench test the PS1 bottom board on its own (no top board attached) to determine if the bottom board will run a DC motor, and change its direction by applying on-off-on power??

Thanks again guys......it has been a steep learning curve for this old AC armature and field coil magnet model train nut.

Peter.....Buco Australia.

PS-1 bottom boards have no logic to operate motor.  You can manually trigger the relay to see if it will drive motor.  G

Thanks for that GGG......like I said way back in this thread..."You learn something new every day".

Now, what I would like to learn today is.....How do I manually trigger the relay to see if it will run a DC can motor??

Peter.....Buco Australia.