IJ and 10 Opto Board

Michael Roma

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My Williams IJ is starting to act a little flaky. When the ball is in the upper half of the playfield near the pop bumpers I hear Shortround say "You cheat Dr Jones" when he shouldn't be. I saw an older post on RGP where the op had a similar issue and a recommendation was to check the 10 switch Opto board for cold solder joints.well I pulled mine out to find a nice little job done on it (see below).

I do not see any cold solder joints on the header pins but am now thinking that perhaps the "i've seen better days" resistors might be the culprit. the manual has the values for those at 220 2W, 1/2W. i tested the ones currently on the board and they are 270 ohm (the same as the ones on the 7 ball trough pcb). I have a bunch of new 270 ohm resistors that I have left over from when I replaced the ones on the trough pcb. Are these safe to use these on the 10 switch Opto board?

- Mike

IMG_0540.JPG
 
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Nice soldering someone did there :( If the opto board isn't the culprit check the big filter caps in the backbox. Sometime they get loose and when the pop bumpers are firing they shake around and dirty voltage gets sent to the optos which results in false readings. Check the switch matrix in test mode and see if you are getting funny results when the pop bumpers are firing.
 
I ended up reflowing the header pins on the 10 sw Opto board and replacing all the resistors that looked like crap. I also pulled the 3 drop target Opto board and reflowed everything on that.

I replaced everything and so far everything is playing great. ;)

Thanks for the heads up on the replacement board. If this turns out to not be a permanent solution I may go that route.

- Mike

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Good job working on that - looks a heck of a lot better.

The U1-U3 ICs can also take a crap on that board.

If it gives you issues again, there's always the GLM board.

RussM
 
that resistor at R31 looks a bit funky

what does it OHM out at ?
if it's within 10%, you are ok but if it's over 10%, replace it
 
that resistor at R31 looks a bit funky

what does it OHM out at ?
if it's within 10%, you are ok but if it's over 10%, replace it

It was 270ohms. It was the only one that the previous owner didn't mess with. The others were within range but the work was suspect.

Still working like a champ!

- Mike
 
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