View Full Version : C64 High Pitch noise...
12-30-2005, 03:50 PM
I'm using a C64 with CynthCart:
My only problem is that for some reason the C64 always puts out this high pitched buzz which of course really messes things up when trying to record. I've pulled the C64 far away from my other electronic equiptment and the buzz stays. Is there some way to get around this? I've never taken a musical science class or anything so...
12-30-2005, 04:04 PM
Possibly some (electrolytic) capacitors involved in the audio circuitry or voltage generation have died over the years. If you have the equipment (probably not) you could measure the ripple (AC) of SID's voltage input. If that's okay you could check SID's analogue output, must be in the line-out amplifier then (sorry, got no schematics at hand right now).
It's probably no bad idea to exchange all capacitors in that area since their life time is limited.
12-30-2005, 05:05 PM
Sorry to "hijack" this thread a bit, but what is the realistic lifetime for electronics made in the '80s?
I have several bits of equipment that I'd like to see still working in the next few decades! Any tips on treatment, storage, use, etc? Or should I just bite the bullet and replace things when they fail?
Capacitors are always the first things to go. Typically replacing the electrolitics (little metal cans) and the tantilums (less common small glass-like teardrops) will keep your old electronics kicking far into the future. I've brought back to life tv's and tape decks from the '60s by replacing all the bad "caps". Last month I brough back to life a 1978 Space Invaders Cabinet. (Anyone looking to buy one? :-) ). I tracked down ~8 electrolitics and one tantilum that had gone bad. To bring this back to the original SID question..... I had to replace about 4 bad IC chips that were bad in the sound circuits to complete the repair. One of the most common failures in the old 64's was also the SID chip. It will make odd noises, incomplete sounds or no sound at all if bad. With the 64's age it's possible that caps on the motherboard, or possibly in the power supply are going bad. If the power to the system is unstable because of bad caps, it will put noise in the sound. I would first try another power supply if you have one handy, then another SID chip (every one has 2-3 lying around right?) and last, replace any electrolitic caps in the sound circuit. You can find helpful schematics on the internet to find any related caps. If I have time I will dig up my old doc and tell you the numbers on the caps. Last you could just get another C64 (or better a C128) off of ebay or such for less than $25 :-)
12-30-2005, 07:37 PM
then another SID chip (every one has 2-3 lying around right?)
Lol, yeah, if only.
I really wish a fab house would do another run of the old 6581.
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