(Topic ID: 84283)

WPC-89 Sound Board #1 - Repair Log / Discussion

By johnwartjr

10 years ago



Topic Stats

  • 5 posts
  • 5 Pinsiders participating
  • Latest reply 1 year ago by Gorgar666
  • Topic is favorited by 8 Pinsiders

You

Linked Games

No games have been linked to this topic.

    #1 10 years ago

    The internet seems to lack quality troubleshooting information for WPC-89 sound boards.

    I'm not sure if it's a matter of the boards not failing often, the repair being above the skill level of the 'average' pin tech or what.

    Regardless, I've got *3* to repair. I picked the nicest looking one first, because it made the most sense to start working on the one that is the best overall condition. Plus, of the other 2, one had a big scorch mark where at least 1 cap caught fire, and the other is missing a few parts.

    The board is unhacked. It has had some solder reflowed on the back of the board, and may have had the amplifier replaced, based on a little flux residue around the amp. But, no ICs have been replaced, etc.

    It produces no sound. No hum, no clipping noises, just no sound.

    I buzzed out the amps legs to the schematic, to make sure I don't have an issue with previous rework - all 5 legs are connected to where they *should* be conected.

    I tested the ROM, 6809 and both Yamama Sound ICs in my test fixture sound board, and they all operate fine in it.

    The board gets +5 and +12 from the driver board, and both those voltages are present.

    It appears the 4 fat diodes, 4700 uf caps, and voltage regulators produce +12 and -12. Both those voltages are present.

    The processor is running.

    So, can someone point me in the right direction to do some troubleshooting? I read on Pinwiki that dried out caps can cause some issues, but those all seemed to tie into problems with sound quality - not with getting no sound.

    Any nudges, gentile or otherwise, or suggestions, are appreciated!

    #2 10 years ago

    I know the only 2 that I had that would not work, replacing the amp is what got them working. As I recall the amp showed a little damage and would flare up if power on. I agree not a whole lot on them when I looked either

    #3 10 years ago

    If voltages are present yet nothing at all out of the amp (touch the back solder pads of the amp, you'll get a hum) then the amp likely is the issue.

    --
    Rob Anthony
    Pinball Classics
    http://LockWhenLit.com
    Quality Board Work - In Home Service
    borygard at gmail dot com

    1 year later
    #4 8 years ago

    repair details:

    Williams WPC-89 Sound board (Funhouse (version L-2) with prior repairs. Capacitors dried-out/out-of-tolerance): 6264 Static RAM IC and 28-pin socket. New 7812 and 7912 voltage regulators. LM1875 amplifier and TO-220 Sil-Pad. NOS 27C020 version L-3 U18 Sound ROM. U14 and U15 Sound ROMs removed, internal data verified and labeled. All socketed ICs removed and checked. 4x 1uf/35v tantalum capacitors (C28, C29, C46, C47). 22uf/50v/105c, 5x 47uf/25v, 2x 47uf/35v/105c, 100uf/25v/105c and 2x 4700uf/35v/105c capacitors. All headers and fuses reflowed. Fuses removed and checked -- okay. Two-tier full functional testing:

    Ref from Clive

    Basic semi normal repair for the board

    6 years later
    #5 1 year ago
    Quoted from JamesH007:

    I know the only 2 that I had that would not work, replacing the amp is what got them working. As I recall the amp showed a little damage and would flare up if power on. I agree not a whole lot on them when I looked either

    What do you mean flare up on power up? 8 years later. Lol. Do you mean pop and smoke a tiny cap?

    Reply

    Wanna join the discussion? Please sign in to reply to this topic.

    Hey there! Welcome to Pinside!

    Donate to Pinside

    Great to see you're enjoying Pinside! Did you know Pinside is able to run without any 3rd-party banners or ads, thanks to the support from our visitors? Please consider a donation to Pinside and get anext to your username to show for it! Or better yet, subscribe to Pinside+!


    This page was printed from https://pinside.com/pinball/forum/topic/wpc-89-sound-board-1-repair-log-discussion and we tried optimising it for printing. Some page elements may have been deliberately hidden.

    Scan the QR code on the left to jump to the URL this document was printed from.