Centipede PCB high pitched "Hum" & static on screen...

[bit_slicer]

I take it this means the PCB is fine and an ARII rebuild kit should be added to the shopping list?

I think an AR-II rebuild kit would be a great place to start. If R29 or R30 look damaged in any way I would replace those too, with 100 Ohm 1/4W resistors.

 

[keithsarcade]

Rebuilt the ARII and popped in a new big blue, no difference. Any more ideas?

 

[keithsarcade]

Anyone....

Bueller....

 

[7146aaron]

AR

Huh. Did you replace the 2 large filter caps on the AR? Try putting your AC meter on the 12 vdc power to the board and check for ac in the dc voltage that powers the sound.

 

[Heinous]

Check for voltage with the game running at R-29, R-30 on your AR II. These are the voltage sense resistors for the +5 regulator. If you have more than 0.2 vdc across either one, you have a bad connection between the edge connector, and the AR II. R-29 is for the positive side, R-30 is for return. These resistors go bad as a symptom of bad connections. The problem is most likely at the edge connector. After you repair the problem, reset the +5v.

Eric

 

[keithsarcade]

Whatever is in the Bob Roberts rebuild kit, thats what it got. I was thinking edge connector also, but I havent seen a problem with it. Ill try scrubbing it again. Ill take some more readings sometime soon.

 

[Rommager]

I have heard that electrolytic capacitors can make high pitched squealing noise if they are going. Also, the ripple in the screen might indicate the same thing.

Not sure if you can narrow down the general area of the board that is making the noise? Try carefully prodding or lightly thumping the electrolytic caps with a pencil eraser while the game is on to see if you can hear a difference in the squeal. It might help you narrow it down to the faulty part.

Good luck!

 

[keithsarcade]

Time to wake this thread back from the dead. Yeah, its still working even with this minor issue but its time I get back to this before I burn up my recently rebuilt ARII. I'm going to try replacing a few pins on the edge connector. Ive heard there is at least one (if not a few) pins that are notorious for making poor contact with the PCB, so my question is simply... which pins are generally the culprit? Anyone know?

 

[keithsarcade]

Anyone? Bueller?

 

[bit_slicer]

Time to wake this thread back from the dead. Yeah, its still working even with this minor issue but its time I get back to this before I burn up my recently rebuilt ARII. I'm going to try replacing a few pins on the edge connector. Ive heard there is at least one (if not a few) pins that are notorious for making poor contact with the PCB, so my question is simply... which pins are generally the culprit? Anyone know?

Any of the power pins are suspect. But especially the +5V since it uses the SENSE circuit. But you're better off replacing all of them.