Great info here Marty,
http://www.pinrepair.com/de/index3.htm#sound
Check your ground straps to the display board. Clay's doco also explains the revision of the boards.
Thanks Nino,
I've re-checked the grounding straps, from the backboard (tightened up the one which goes onto the locking mech, but others all good. Checked its path back to where it hits the transformer and all in tact.
According to Clay's site it states the sound board should be 520-5050-03. The sticker (little white one) on mine reads 520-5050-02. Clays states the boards are not upwards/downwards compatible then further reading (google) suggests it can be changed with jumpers? I am a little confused with the jumpers as to what I should have. As far as I know I am getting sounds / music that I should be.
So if this sound board is OK to be used (nil probs except for hum / G.I noise) I will look at changing the cap.
His site states:
Also it could mean the large filter capacitor (usually 1000 mfd at 16 volts) on the sound board needs to be replaced. Look for a large capacitor that connects +5 volts to ground.
This is the second part. Not having the schematics I don't know which is the 'larger capacitor that connects +5 volts to ground' on the actual sound board. From a visual inspection there is a larger capacitor on there (well bigger than others). Third question what replacement do I purchase - ie 1000 mfd filter capacitor or is a greater one required?
Thanks again
