(Topic ID: 42345)

Distorted Sound WPC


By robm

6 years ago



Topic Stats

  • 10 posts
  • 6 Pinsiders participating
  • Latest reply 6 years ago by robm
  • Topic is favorited by 3 Pinsiders

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#1 6 years ago

I have an Addams that was working fine (the sound board was one that i grabbed from a project machine that has not been powered up for probably 8 years - but worked fine for a number of weeks), then the sound became quite distorted - like it was playing underwater and very scratchy.

I have -

reseated ROMs, socketed IC's and ribbon cables heaps of times

replaced caps C15,36,38,20,23,46,47

Speakers are fine at 4ohm and pull in with a 9V battery

I'm wondering where the next place on the sound board is to look at replacing/fault finding - there seems to be very little repair information on these boards....

Thanks

Rob

#2 6 years ago

I was thinking caps and ribbon cables. But if this played for weeks probably no chance it is cables. Sorry my knowledge is limited.

Do you have any other machines with the same board set? If so you could swap them to see if the problem moves with your board. Or goes away with a different board and roms installed.

#3 6 years ago

Yeah, i've also swapped boards and the problem follows - so its definitely a board issue

#4 6 years ago

I had a similar problem, K's arcade took care of mine. It took a couple weeks longer than expected but I was very satisfied with the repair.

http://ksarcade.net/board-repair-services/

#5 6 years ago

the board powersupply making voltage correctly? you check that 5v is stable?

#6 6 years ago

The 47uf caps on that board fail often. Might not be a bad place to start.
--
Chris Hibler

#7 6 years ago

I had performed a speaker replacement on my Addams and when I put in the new sub, the backbox speakers lost a lot of their high end and sounded really muddy / hollow. I ended up replacing C24 and C25 (4700uF 35V) capacitors and it brought the high end back. Huge night and day difference.

Big thanks to PinWiki for the suggestion.

#8 6 years ago

Changing C24 and C25 makde no difference. I replaced a heap of other capacitors without any luck. In the end, i replaced 5 more capacitors - i am unsure which one (or ones) made the difference as i changed them all before testing again. The ones i changed were:

C34 and C37 (one was a 47uF, the other 1uF - i don't recall which was which)

C26,C27,C28,C29 (all 1uF)

Many of these were tantalum capacitors, but i replaced them with more readily available electrolytics. Anyway, the sound is back to completely normal now. If i come across this issue again, i will try and narrow it down to the exact capacitor!

#9 6 years ago
Quoted from robm:

Many of these were tantalum capacitors, but i replaced them with more readily available electrolytics.

Although this appears to work, those tantalums were there for a reason. They exhibit characteristics that electrolytics do not.
--
Chris Hibler - CARGPB #31
http://www.Team-EM.com
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The Place to go for Pinball Repair Info

#10 6 years ago
Quoted from ChrisHibler:

Although this appears to work, those tantalums were there for a reason. They exhibit characteristics that electrolytics do not.
--
Chris Hibler - CARGPB #31
http://www.Team-EM.com
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The Place to go for Pinball Repair Info

So does this mean i might have problems down the track? I just can't source the tantalums from my local supplier. Or are the differences that small that it may not be noticeable?

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