wizard of wor hum

videorob07

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Hey all.
Need to get my WoW working proper before super bowl party.
Game works fine, except for the humming which is louder than the game ,even when in attract mode.
All I have to check things with is a multi-meter and the manual.
Sound board?
Let me know what I can check for.
Thanks, Rob.
 
the pots on the sound board will usually make a shitload of noise (crackles, etc) when adjusting but should stay quiet when not being touched. i'd check your voltages too, in case the +12 is high... you can test them all at the connector on the right side of the board cage where the connector plugs in (on the outside of the cage). if you pull the connector off there should be a sticker underneath listing what pin is what voltage. but definitely check the grounds as well.
 
im guessing some(sound) pins inside the connector are weak and not gripping the game board PCB tight enough. or, the capacitor in the audio circuit is dried out and isnt doing its job.

very, very carefully move the connector to the game board (slightly) and see if the hum goes away. if it does then the pins need replacement. but im talking very carefully move the connector as you can damage the PCB. i had a PAC MAN that did the same thing and when i moved the connector (torque) it went away. the (temporary) fix was wire tying (screwing) the wire harness to the cabinet so the hum wasnt there anymore.

those electrolytic capacitors dry out over time and dont do what they were supposed to do. stress is put on other components in the circuit and they should be replaced.

i read someplace the military tests their capacitors every 5 years. yours are probably close to 20 years old ish, and should been replaced 10 years ago. funny how so many boards still even work today but they do.

happy new year everybody ! time to kiss the girlfriend !
 
Ok, no luck so far.
turned the volumes down so I can hear the hum good.
Checked the grounds, all seem good.
Checked the connectors, no change when moving then around.
Checked the voltage on the cage, 12.2 and 5.1 volts.
Any way to check the caps, or just replace them?
Thanks, Rob.
 
ok, manual lists 5 cap for the board
470uf16v
4700uf25v
10000uf35vdc
20000uf16vdc
20000uf35vdc

I have a local electronics supply I will hit tommorow.
What values can I go up or down on if they dont have an exact match?
Are these generally hard to find?
Thanks, Rob.
 
You can always go up in voltage. The 470 and the 4700 should be easy ones to find. The 10000 should also be easy to get. The 20000 is a bit of an old value, probably going to find 22000's, which should also work. On electrolytics this big, you can easily go up in value a fair amount with no ill effects.

But before spending lots of money on caps, check your power supply rail to the sound board for ripple. Use a scope and have a look. Or, if you don't have a scope, set your meter to DC volts, and see if it fluctuates.

Oh, and since nobody has mentioned this, I'll tell you why it's humming - it doesn't know the words.

-Ian
 
i had the same prob with mine a few years back. it is NOT the power supply. i put a switcher in mine and it still did it. i changed the fuse holders and it still did it. finally, it came down to the transformer beleive it or not.

i replaced the xformer and it went away.

the machine worked fully and u could play it, but there was a loud buzz sound and white line scrolling the screen vertically.
 
no luck so far on the humming.
replaced the caps on the power supply board and on change.
What about the audio amp board? the one with the three pots for the left, right and wizard sounds. Looks like 4 caps on that small board.
Will grab those tommorow and see what happens.
Rob.
 
Ok, replaced the caps on the small audio board (the one with the three sound pots) and still no luck.
Re-checked the grounds and all are solid.
This humming is getting annoying. Can here it over the other games.
Someone mentioned the transformer.
How hard is that to find and replace?
Let me know if anyone has any ideas.
Thanks, Rob.
 
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