Problem Pinball CPU 5v ground short

[Ronnie Dent]

Yes that area was repaired 5 years ago and it was fine until now, seems I'm chasing my tail! I snip the pins of vcc on hot chips then others get hot! the only voltages that go to this board are 5v and 12v I think I have snipped 6 vcc pins and the short has risen to 3 ohms.

Thanks Ronnie

 

[duncthepunk]

hi looks like battery leakage from the picture the only way to stop any more damage is to desolder all the parts of the board tha are in affected area (shine a light from the other side of board to see the damage). you could try to neutralise it with vinengar and a brush . it will start to bubble leave a couple of minutes then wash off with distilled water or iso alco . the sockets will most probably need to be replaced. be carefull with the tracks as they lift with to much heat . go to pinwiki website . wher are you based ? . i am in birmingham in uk . be carefull when injecting voltage in the board because of the short will send voltage to other chips and they are easly damaged. you can go to pinball database .find your machine and they should have a diagram of parts required . hope tha helps .goodluck

 

[Ronnie Dent]

hi looks like battery leakage from the picture the only way to stop any more damage is to desolder all the parts of the board tha are in affected area (shine a light from the other side of board to see the damage). you could try to neutralise it with vinengar and a brush . it will start to bubble leave a couple of minutes then wash off with distilled water or iso alco . the sockets will most probably need to be replaced. be carefull with the tracks as they lift with to much heat . go to pinwiki website . wher are you based ? . i am in birmingham in uk . be carefull when injecting voltage in the board because of the short will send voltage to other chips and they are easly damaged. you can go to pinball database .find your machine and they should have a diagram of parts required . hope tha helps .goodluck

Thanks for the informed reply, all that work was done 5 years ago, what you see is fresh solder mask covering the cleaned up area so all tracks sockets etc were new in that area

I found the short on a chip but also another 15 or so chips are bad! Conclusion is some stray high voltages zapped the board!

 

[Ronnie Dent]

A picture of the board in question

 

[duncthepunk]

if you give pinball heaven a ring .he might have a contact who fixes these boards . i think the man is called jim gunn . he fixed a guns and roses power board for us a couple of years ago. a new board without chips is about 400 plus postage (gulp)but no more battery problems . with everything disconected from power supply test the voltages coming out of the power supply and see if they are correct ? . i do recall that one of the caps short and sends coil voltage all over the place (not good) this happen to the guns and roses

 

[Davespice]

Not sure if this is helpful, but I know a trick that works on pretty much any type of PCB. Hook it up to a bench power supply and inject a lowish voltage, lower than operating voltage, say 1 VDC for example. So you are basically going to let current pass to ground through the short continuously but at low power. You then examine the board using a thermal infrared camera to see where it is getting warm. That can sometimes indicate where a short is.

 

[Ronnie Dent]

Thanks guys, in the end we found another board which has no corosion but had a fault and without the custom sound chip, managed to find a sound chip and think the fault is the custom pal so just waiting on a replacement for that

 

[Fantazia2]

If its an early whitestar with the BMST2000 then there is a guy over on pinball info that is looking to do a repro board for them with I think a redesign for modern components.

Actually looks like you are already over there posting.