OP

Quoted from Brewchap:

I recently used the MPU board to test in another pin trying to narrow down a problem. This may or may not been the cause of this problem. Since then I started to get errors at boot up. Check Opto Switch 81, 82, and 83. With this being a switch matrix problem, I first ruled out the MPU using a Pintech Switch Matrix Tester. I then started looking over the playfield looking for a short of some kind that used the wires colors White/Brown, White/Red, and White/Orange.
This led me to the Accelerator Board Assy. Here I found that several leds where out, pulling J5 allowed the leds to come back on again and the lights to disappear on the switch edge test. This lead me to believe that the problem was on the Accelerator board. Here I deducted that U1 LM339 was bad, so I added a socket and replaced U1 with a new chip.
This did not change a thing. So now I am scratching my head, trying to figure out what I may have missed. Any ideas? Dont think that its a shorted circuit, but I could be wrong.

OP

Quoted from Brewchap:

There are 3 leds that are out when J5 is connected. I pulled one by one the wires and each time an led came on. But the errors keep coming back even with the wires are unplugged from the connector.
How do you test for a bad opto?
I also just added 2 more errors...switch 84 and 85

OP

Quoted from Brewchap:

No I didnt. I did test them with a volt meter and they only read in one direction. But I will change them out to see what happens.

OP

Quoted from Brewchap:

Well I think that the opto tested good.