planemusic
New Member
Hi all,
I'm working on an Adcom 555 that I've had in my stash of hifi for over 10 years. A friend gave it to me after it stopped working. He said it had stopped working after he tried to hook up an old tube preamp up to it. The amp would turn on but not make a sound. The power fuse was good. The fuse for the left channel PNP output PCB was bad. All other fuses were good.
Upon inspection of the input PCB, many of the components were visibly burnt. Different components on different sides of the board - damage in both channels.
My problem is this: I can not seem to locate a schematic or PCB layout for this particular board. It is labeled17-087. None of the components are marked. Some of the schematics I've found online are similar but they reference a board that looks dramatically dissimilar to the one I have here. They also use differing transistors. The board I have here uses quite a few MPSA93 transistors
On one channel I was able to replace a couple MPSA93 transistors and that brought the right channel back to life. The left channel still blows fuses in that PNP output. I'm left shooting in the dark without any documentation
Does anyone have a matching schematic or PCB layout to this board? Other helpful trouble-shooting tips also appreciated.
Thanks!
I'm working on an Adcom 555 that I've had in my stash of hifi for over 10 years. A friend gave it to me after it stopped working. He said it had stopped working after he tried to hook up an old tube preamp up to it. The amp would turn on but not make a sound. The power fuse was good. The fuse for the left channel PNP output PCB was bad. All other fuses were good.
Upon inspection of the input PCB, many of the components were visibly burnt. Different components on different sides of the board - damage in both channels.
My problem is this: I can not seem to locate a schematic or PCB layout for this particular board. It is labeled17-087. None of the components are marked. Some of the schematics I've found online are similar but they reference a board that looks dramatically dissimilar to the one I have here. They also use differing transistors. The board I have here uses quite a few MPSA93 transistors
On one channel I was able to replace a couple MPSA93 transistors and that brought the right channel back to life. The left channel still blows fuses in that PNP output. I'm left shooting in the dark without any documentation
Does anyone have a matching schematic or PCB layout to this board? Other helpful trouble-shooting tips also appreciated.
Thanks!
