Newark, OH
No sound back box speakers. Johnny mnemonic. Sound distored and low from cab speaker.
(Topic ID: 250551)
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Quoted from YeOldPinPlayer:First thing to check is the wiring. Is everything connected securely?
What is your troubleshooting skill level? Do you have a multi-meter and know how to use it?
Everything has good connection. I do have meter. And skill are good. No backbox sound but cab has sound but very low and distorted.
Quoted from YeOldPinPlayer:I would check the voltages at J3 & J4 on the sound board. (page 3-26 in the manual)
Be sure and reseat and inspect all the connectors. Pins can tarnish and build up resistance. If the voltages and connectors check out I'd probably try another speaker with the correct impedance just to make sure the speakers are not the problem before I started troubleshooting the sound circuitry. Unfortunately the manual from IPDB doesn't show the sound board schematic (if it does, I overlooked it.)
Also, you might consider asking the moderators to move this to Tech: Modern to get the most eyeballs on it. pinballmaniac40 might have some ideas.
No volts on j4. J3 has 4.3v dc
2 months later
1 month later
Hello all. I ordered a repair kit for my johnny memonic pinball cause its had sound issue. No sound from backbox and very little sound from cab. I replaced the 10000uf caps and the 2 amps. When i power it on get a loud humming sound like a electric dead short. I disconnect the ac volts feeding and it dont do it. So im not sure where to look maybe transformer? Thanks.
Quoted from PinballManiac40:Sounds like you damaged the feedthroughs whre the 10000uf caps fit into. These feedthroughs connect the solder pad of the top side to the solder pad on the bottom side of the board.
I fixed that no more loud hum. I replaced amps and the 2 10000uf caps and u21 chip and same issue as i started with. Very low garppled sound. Idk anymore.
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