Intermittent 12v power issues WPC89

[Jason Catrine]

Hi folks,

I’m thinking i have an issue with my power driver board on demolition man but wanted to check here first to get a second opinion.

Symptoms….

Issue 1 (minor) - quick tap of start button doesn’t register- need to hold it in for 1 second.

Issue 2 (major) - power tends to come on the machine but it will reset once each time, normally within a few mins. You don’t need to be playing the game for it to reset, will just bounce without any games played. Once it reboots, the game is absolutely fine. Had it on for 4 hours the other night just to see if it stayed on after it had its initial hiccup and it appears to. I’ve just put in a new pinsound cpu board in September so i am assuming thats not at fault here.

I’m thinking 12v rectifier and possibly also the capacitor but i really haven’t a clue when it comes to electronics and i’ve only got that from googling.
I’ve managed to capture the issue. As you see from the video, the cpu board isn’t getting proper power and the 12v led on the power board is coming on and going off.

When the game works, the 12v led stays on properly and checking with a meter the voltage remains good and consistent.

And if people think my diagnosis is correct, is there anyone who can repair it or anyone selling a cheap replacement board? I don’t feel confident enough to try and fix it myself as its too expensive a part for me to be practicing something i’ve never attempted before.

Thanks,
Jason.

 

[Calimori]

Have you got reading for each of the test points? Share them here. Do them as is, and then with the power drain elements removed, as per this guide: https://homepinballrepair.com/troubleshooting-williams-bally-wpc-pinball-machines/

Whilst the rectifiers and caps are likely ages items, there no point changing them if they are not at fault. Resets are usually 5v digital, and I think that is TP1 (don't have a board in front of me but wanted to help) which is 12v power so not part of the same circuit (different AC in as well as connectors)

As for the off button issue, is there a mechanical playfield toy with sensors that moves at start up and if that isn't in the right place, the start button wont activate? WH2O has Bigfoot who's head has to be in the right place for example.

 

[Calimori]

@Paul is making replacement boards. And a few of us could repair it but do above first so we know what the issue may be.

 

[Pick Holder]

OKAY = Change the pins and the connectors on the power input and output areas. Had many weird issues. Do not just change the pins - do the connectors too - most important.

It is worth changing rectifiers and the other parts to the 12v unreg, 12v reg and 5v circuits.

Change the electrolytic caps - especially the small one by the 12v regulated regulator.

 

[Jason Catrine]

Have you got reading for each of the test points? Share them here. Do them as is, and then with the power drain elements removed, as per this guide: https://homepinballrepair.com/troubleshooting-williams-bally-wpc-pinball-machines/

Whilst the rectifiers and caps are likely ages items, there no point changing them if they are not at fault. Resets are usually 5v digital, and I think that is TP1 (don't have a board in front of me but wanted to help) which is 12v power so not part of the same circuit (different AC in as well as connectors)

As for the off button issue, is there a mechanical playfield toy with sensors that moves at start up and if that isn't in the right place, the start button wont activate? WH2O has Bigfoot who's head has to be in the right place for example.

I can get the fault to appear before initialisation if i turn it off and on again directly after a good boot. And at that point the playfield lights and mechs haven't kicked in. The only proper mech on demo man is the cryo-claw thing but it only self tests after the power gets to the playfield and the power issue occurs before any lights on the playfield kick in. The pinsound cpu has the 5v 'no more reset' thing built in, which is why i was thinking its probably not that. Plus the 5v resets i believe are normally mid-game when it hits high voltage mechs. My issue can occur without starting a game or hitting a mech - so assume not the 5v issue - but this is all just assumptions from google.

If the 5v usual fault was the issue would the 12v led struggle and turn off/on in sympathy? Is it still a power board issue? I assume my new pinsound board isn't faulty?

J.

 

[Paul]

Simple Q - did it have this problem before you installed the pinsound? if that is the only thing that has changed, is there any way you could change back to the previous board and see if you still have the issues?

Sounds silly, and i am very guilty of this - one small step at a time... I tend to try to jump in "oh it must be that".. however i have had to re-learn to change one thing at a time to allow an issue to be isolated, else you spend most time chasing your own tail!

I can get the fault to appear before initialisation if i turn it off and on again directly after a good boot. And at that point the playfield lights and mechs haven't kicked in.

My spidey senses say Capacitor issue... bearing in mind that the Power Driver will more likely be 30+ years old now (unless it's a rotten dog, when i would recommend taking it out and replacing it altogether anyway!)... There are certain suspects (along with remembering the Caps are now 10+ years beyond their working life...) and as Mr Pick Holder says above, you tend to find the power in and out connectors on the Power driver are either singed or can be worn to the point where you dont get the best contact with them any more....

If you need it testing then more than happy to give it a once over for you

Edit - just had another thought - could be as simple as a dry joint... Check the connectors on the power driver board along with any of the large caps and bright rectifiers for dry joints...

 

[Jason Catrine]

Thanks @Paul. The cpu board was dead when i got the game so I’m not sure if there was power issues at that time. The batteries had leaked and destroyed the board and the machine blew fuses when turning it on. I don’t have the original board anymore as i gave it away…..to you

I’ll hopefully get some time tonight to take the board out and have a good look at the back of it to see if theres any obvious looking issues. If i cant see anything then your offer of having a look at it for me would be absolutely amazing. Thank you.