PAC-MAN (Noise problem)

[BUCKETHEAD]

My PAC-MAN machine has started making a noise,

The best i can describe it is ?

Well it sounds like WIND blowing in a mircophone.

It will do this for a while then all of sudden quit.

Then start doing it again a little while later.

You can still hear the game sounds, But at times this WIND like sound will be

louder than the game itself.


Any ideas what my problem may be here

Thanx in advance ??


Bucket ..

[RayB]

From speakers or from monitor?

[BUCKETHEAD]

From the speaker.

Sounds like wind blowing into a microphone and then coming out of a speaker.

[tbombaci]

Check the volume POT. It maybe loose or (going) bad.

Alsom the sound amp be be on it’s way out.

-Tom

[tbombaci]

From Mowerman’s site:

Sound Problems


No Sound, Hum during Sound.

 Rams @ 2L & 2K bad

 Clicky Sound

 Replace 74LS174 @ 1L

Buzz in music & after game over but not before start of game upon initial power up or reset.

Replace 4066 @ 1N.  Placing O-scope on R1~R4 will show noise from bad 4066.

 Distorted Intro Music–Other Sounds okay–Seems thermal/Cap like

Replace 74LS174 @ 1L bad on Pin 14. Bug trap only shows when starting game.

Muffled Sounds, seems like intro music is Slow.

Pin 10 @ 2L (RAM 7489/82S25) out of circuit.

 Intermittent loss of Sound (Static)

 Modification

    * Cut trace to pin 1 of 2M (74LS273).
    * Solder 1K resistor from +5VDC to pin 1 of IC 2M

-From Service Bulletin 5/19/82

Note

 All chips in the sound section will bug trap.

Some Sounds seem ok, some seem bad /off.

Check R1, R2, R3, R4 for signals during Music / Noise.  Each should have ‘Digital Waves’ (squared, stair step sine waves as seen on an O-scope).
Lack there of go to 2M 74LS273 and check pins 2, 5, 6, 9, 12, 15, 16, 19 as these are all outputs.

[BUCKETHEAD]

Thanks man !

That is alot of good info !

Don't see any WIND blowing in a Mic symptoms though ??

LOL ! 

Thanks!


Bucket ...