(Topic ID: 116651)

WPC all switches don't work

By dudah

4 years ago

Topic Stats

  • 6 posts
  • 4 Pinsiders participating
  • Latest reply 4 years ago by dudah
  • Topic is favorited by 2 Pinsiders


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#1 4 years ago

So I got this DM. Game worked fine. Shopped it, put in LED's, replaced the big caps and bridge rectifiers on the driver board. Plug everything back together, game boots fine, but NONE of the switches work, can't start a game! Even the service buttons on the J205 direct switches don't work.

I noticed F105 was dead and replaced it, the schematics say its for "HI POWER PULSE", doesn't blow anymore. Coin door interface board/connectors looks good.

I forgot I shouldn't be installing LED's with the game on. Looking at the schematic, it appears I may have blown U16-19, LM339's which apparently go bad. New LM339's are on their way. U13 and U15 could be blown also but figure U16-19 is a good place to start. Game is at my brothers and I just discovered this today, haven't had time to bust out the logic probe yet.

This sounds like it may be a stupid problem and I'm just not seeing something obvious - anything I'm missing?

#2 4 years ago

Why did you replace all the bridge rectifiers and caps?

LM339s don't just 'go bad' like a week old loaf of bread.

Go back over your work. Connector off somewhere? All voltages on the driver board present and appropriate?

#3 4 years ago

Maintenance, plus the previous owner did a crappy job soldering the last ones that had a lot of extra/cold solder.

Truth, I think it was because I was installing some of the LED's with the game on. I'll dig a little deeper when I go back in a few days.

#4 4 years ago

If your plan is to replace the LM339s, you're just digging a deeper hole, they're not bad. You took out traces/thru-holes when you replaced the bridges and caps (blanket replacement of these parts is ALWAYS unnecessary) and lost 12V for the switch matrix, and dedicated switches. That's my educated guess by your description anyway.

Measure all your voltages from the driver board, you'll likely find the switch matrix regulated 12V is now gone.

Rob Anthony
Pinball Classics
Quality Board Work - In Home Service
borygard at gmail dot com

#5 4 years ago

Go back and look at your BR1, C6, & C7 caps. As Borygard said, loss of 12 volts is going to be your issue. Since you replaced that bridge and caps & now you're having the problem, most likely those are your issues. Those are going to be responsible for providing the voltage for your 12 volts for the switch matrix. Check for continuity between those caps and the bridge. You may need to run a few jumper wires if you're not getting continuity.

#6 4 years ago

I didn't know that the switch matrix needed 12V! Tracing my way through the schematic, I noticed that the + output of BR1 has a top and bottom solder trace, it wasn't making contact to D1 on the top! Fixed that and everything works. Thanks for the guidance!

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