Hi Ed, et al. Yeah as you saw +4/264 didn't have a SID we made the raucous squawking noises on the same chip as the video. The order of things is pretty much: 1)Check power supply which is why it was recommended to check the fuse. I would also check any other voltage pins directly on the SID: +5 on pin 25 and +9/12 on Pin 28. 2)Since it is socketed, swap the part. 3)Finally if you have a scope look at the output directly on pin 27, you should see at least ..3v-5v AC when it's working. You should actually see roughly the same amplitude of AC signal at the output Pin 3 on the DIN as the transistor is an Emitter Follower and doesn't have voltage gain. If you are losing the signal through the transistor stage, it could be that the transistor is gone or that C77 or C76 have dried out being that they are 25 years old. The good news is that since you hear sound (as opposed to utter silence) it should be fixable. I used the schematic at http://www.zimmers.net/anonftp/pub/cbm/schematics/computers/c64/250469-rev .B-right.gif to pull the pin details, as you can see there is not much except the SID chip, a couple of caps for the filter and then the transistor buffer circuit. Good luck, feel free to shoot over intermediate results. Bil -----Original Message----- From: firstname.lastname@example.org [mailto:email@example.com] On Behalf Of Ed Johnson Sent: Tuesday, January 31, 2012 11:54 AM To: firstname.lastname@example.org Subject: RE: LOW VOLUME SOUND C64c It's socked. Best regards, Ed Johnson -----Original Message----- From: email@example.com [mailto:firstname.lastname@example.org] On Behalf Of Gerrit Heitsch Sent: Tuesday, January 31, 2012 11:49 AM To: email@example.com Subject: Re: LOW VOLUME SOUND C64c On 01/31/2012 04:09 AM, Ed Johnson wrote: > I see there are different revisions of the SID chip. I have an 8580R6 > Can I use any 8580 revision SID? Or even use a 6581 ? You sure about the 8580R6? So far I have only seen the 8580R5. You can't use a 6581 since it needs +12V and different capacitors. Sure, that can all be done, but you need to be handy with a soldering iron. Gerrit Message was sent through the cbm-hackers mailing list Message was sent through the cbm-hackers mailing list Message was sent through the cbm-hackers mailing listReceived on 2012-02-01 04:00:11
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