Author Topic: Help with WPC 89 Driver Board Repair.  (Read 8142 times)

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Re: Help with WPC 89 Driver Board Repair.
« on: November 03, 2011, 08:48:59 AM »
Ooookay, thanks for the lesson, I understand a little better now. 

So I measured the left leg of the Tip36 and it reads .575V.

Looks okay?

A TIP36 will be fully switched ON with 0.5V on the base (left leg) - this is why the coil is activated.

Your problem appears to be further back up the chain. Look at the driver to the TIP (the transistor before it) and measure its base - again it should be very close to ground - then look at the parts further back for a clue - I don't have a circuit in front of me but this section is pretty basic and you should be able to track back.

You say you have replaced all of these parts? Any shorts between pins? Are they all inserted the correct way around? Were any substitutions made using parts that MIGHT have a different pinout?
Replacement Pinball PCBs that remain faithful to the originals