jaymz168
Member
- Joined
- Aug 6, 2010
- Messages
- 21
Hi all, first post here after a decade of lurking around
A friend was cleaning out and gave me a pair of non-functional Audioarts Model 1200 compressors. I haven't tried powering them yet because all of the electrolytics inside are leaky and one of them had some sort of destructive failure. One of them has a completely toasted TL072 and socket and the area around the regulators on that unit looks pretty unhappy as well. I'd like to have a schematic to work off of but it seems that even though these were fairly popular and at least one company, Revive Audio, modified them but I can't seem to find a schematic anywhere. The board is pretty easy to follow so I've started to do a schematic in KiCad but I'm stumped on two parts:
https://i.imgur.com/WJq4Shn.jpg
https://i.imgur.com/JWZAC18.jpg
That's first mystery PDIP-14 chip. This picture comes from the "very dead" unit and this package had a full coverage heatsink on it but it fell right off of this one. The heatsink seems to still be well attached on the other unit. This one is driven on pins 3 and 7 from the second and third opamps (pin6 from NE5534s). It looks like it drives the fourth opamp from pins 5 and 8. It has pins 1, 2, 9, 11, 13, and 14 tied to ground. Pins 4 and 6 are paralleled and head off to the sidechain section.
https://i.imgur.com/5QmUzUx.jpg
And here's the second mystery PDIP-14 chip. I'm fairly certain this is the log-amp/VCA as it's over in the sidechain area with a handful of TL072S and a single NE5534. I haven't gotten far enough in tracing signal through the board to take a guess on the pinout. Searching around seems to imply "CA" means circuit assembly but no exact matches.
Hopefully these are both still functional but I'd still like to know what they are to produce a schematic so any help is welcome!
And here are some pics of the carnage in the "very dead" unit, I've got parts coming today to redo the PSUs, all electrolytics and film caps, and the toasted socket and some spare opamps. Once the bad parts are out I'll check for shorts, etc. butgiven that it's the very first opamp that signal hits that died and the guy who had these does a lot of live sound so I wouldn't be surprised if it just took a big hit from something. It's actually in what likes the driver for the peak detection circuit.
Anyway, on to the autopsy:
https://i.imgur.com/ux3PUoj.jpg
https://i.imgur.com/MImlGRA.jpg
https://i.imgur.com/shJGjY1.jpg
https://i.imgur.com/bshAH5m.jpg
https://i.imgur.com/YeUP398.jpg
https://i.imgur.com/NShOeCU.jpg
Full gallery here: https://imgur.com/a/Z2Hg18E
James
A friend was cleaning out and gave me a pair of non-functional Audioarts Model 1200 compressors. I haven't tried powering them yet because all of the electrolytics inside are leaky and one of them had some sort of destructive failure. One of them has a completely toasted TL072 and socket and the area around the regulators on that unit looks pretty unhappy as well. I'd like to have a schematic to work off of but it seems that even though these were fairly popular and at least one company, Revive Audio, modified them but I can't seem to find a schematic anywhere. The board is pretty easy to follow so I've started to do a schematic in KiCad but I'm stumped on two parts:
https://i.imgur.com/WJq4Shn.jpg
https://i.imgur.com/JWZAC18.jpg
That's first mystery PDIP-14 chip. This picture comes from the "very dead" unit and this package had a full coverage heatsink on it but it fell right off of this one. The heatsink seems to still be well attached on the other unit. This one is driven on pins 3 and 7 from the second and third opamps (pin6 from NE5534s). It looks like it drives the fourth opamp from pins 5 and 8. It has pins 1, 2, 9, 11, 13, and 14 tied to ground. Pins 4 and 6 are paralleled and head off to the sidechain section.
https://i.imgur.com/5QmUzUx.jpg
And here's the second mystery PDIP-14 chip. I'm fairly certain this is the log-amp/VCA as it's over in the sidechain area with a handful of TL072S and a single NE5534. I haven't gotten far enough in tracing signal through the board to take a guess on the pinout. Searching around seems to imply "CA" means circuit assembly but no exact matches.
Hopefully these are both still functional but I'd still like to know what they are to produce a schematic so any help is welcome!
And here are some pics of the carnage in the "very dead" unit, I've got parts coming today to redo the PSUs, all electrolytics and film caps, and the toasted socket and some spare opamps. Once the bad parts are out I'll check for shorts, etc. but
Anyway, on to the autopsy:
https://i.imgur.com/ux3PUoj.jpg
https://i.imgur.com/MImlGRA.jpg
https://i.imgur.com/shJGjY1.jpg
https://i.imgur.com/bshAH5m.jpg
https://i.imgur.com/YeUP398.jpg
https://i.imgur.com/NShOeCU.jpg
Full gallery here: https://imgur.com/a/Z2Hg18E
James