Williams System 6 Display 100v was put on 5v line. What's cookin'

[agodfrey]

This is my next project after I finish a 6100.

Working on a Williams System 6 Time Warp. I was getting burnt resistors on segment E and D on player 1, 3, and master display. Pulled the master display to check the board and replace resistors. Got one segment back but one other was out. Also that resistor was heating up. Upon further investigation I think one of the slave displays might be the issue for the heating.....

So I pulled it again to see if I was missing anything, couldn't see anything, so I popped it back in.

ANYWHO it appears the 100v and 5v trace on the master display flaked off and bridged. Took out my 2 logic fuses. Upon investigating further ( when I found the issue) I noticed some coils locking on. So I am assuming I fried the PIA as random sounds are playing. I also think I messed up a 4049, if I follow correctly.

Just looking for a good place to start to see how bad the damage is, what to check, and start getting a shopping list together.

 

[ArcadeTechGW]

You have something crossed.

This is my logic:
1. It is improbable that any chip will have 100 volts run through it.
2. It is improbable that 100 volts should be near those connections

So walk back the lines. You either have a connector off by one connection (putting high voltage where it doesn't belong) or wires pinched / shorted together.

This means going to your ground game - get out the schematics, and look for where 100 volts goes. Look for where it is close ANYWHERE it might get into those connections. Then look in those areas.

 

[agodfrey]

Just want to make sure we're on the same page. Thanks for replying.

So I had pulled my master display to replace some burnt resistors. After putting it off a few times the game locked up.

After investigating I found the 4j7-2 and 4j7-3 were bridged. This photo is more current after I reflowed them. Just for visual aid at this point.


Went to the schematic and saw those were power inputs.


Went to the other section to see what those connectors supplied and saw it was 5v and 100v


So that is why I felt that 100v ended up on the 5v line.

There is no 100v at the moment as I pulled that fuse. It had not blown. The two 5v logic fuses did blow. Again making me think 100v on the 5v line.

So what I'm trying to track down is what might be susceptible. Based on the machines behavior I am guessing the pia is toasted. And I see a few other things. Just wanted to get another option what I should look at/for.

Hopefully that catches you up to what happenend.


Thanks again for your time.

 

[ArcadeTechGW]

Any semiconductor fed on the 5 volt line is more than likely blown. That isn't a little exceedance, and the smoke will come out quickly - faster than the fuses can blow. In fact, the fuses probably blew because components shorted.

So look at the 5 volt line. Look everywhere it goes. Test every component that is on that line.

Or scrap the board and start from scratch. This will be a lot of work.

 

[agodfrey]

That's what I was thinking. Thanks!

 

[LyonsArcade]

When system 8 came out, it was kind of a cross between System 3-7 and system 9 (obviously) so they only made a couple games before moving onto system 9. I had a System 8 Pennant Fever that had the same proble you had on your System 6, the high voltage was shorted to ground though. If you want to see what I did with it there's a playlist here:

https://youtube.com/playlist?list=PLXBCNT6PGQNpUin_Ui80-EJSsEoX5HyD6

 

[agodfrey]

Thanks @LyonsArcade ! Yeah. I did a little poking around today. Looks like I have -100v but not +100v. So I'm going to rebuild the power supply.

Haven't done much digging to see what's shot but that should be next when I get the time.

Could you post that playlist again or dm me. I'm getting not available:

 

[agodfrey]

Looks like I found it on my own. I was just going to reply that I love your channel and then I realized what you meant by playlist!!! Hahah.

https://youtube.com/playlist?list=PLXBCNT6PGQNpUin_Ui80-EJSsEoX5HyD6

 

[LyonsArcade]

That's the one!