Hi Everyone,
I'm not sure whether this is really "Pass Labs" enough to post in this forum, but here goes anyway.
Tombo56 has a thread about his awesome input buffer (https://www.diyaudio.com/community/...ludef-sissysit-and-similar-amplifiers.382345/) and as I posted there I've made a pair and am trying them out in a (very) temporary chassis. I like them a lot, and need to fix them up in a more permanent home. A friend was throwing out his old Sony TA-S7 integrated amp, which he recently replaced because it is giving trouble (outputs cut in and out, volume sometimes suddenly jumps to full in one channel... maybe other things too...) and I rescued it from going to recycling. Initially I thought I'd have a go at fixing it (although I don't think I'd actually use it if it was working) and then thought alternatively I could maybe salvage some parts from it, and perhaps use the chassis as a home for the buffer pre.
Opening it up I found that there is a toroidal transformer, with a nice housing. It looks like the main output is +/- 18 Vac, although I'm not 100% certain I've measured the only secondary winding, since some parts of the power supply section aren't very visiv=ble, and I haven't taken it apart yet. Fiddling around a bit I found that all the remote control functioning works just fine (with a universal remote) with some of the audio circuitry disconnected, and apparently the relays switching the inputs work just fine with the pushbuttons (although so far I can't get them to work on the remote). This led me to wonder whether I could take out the power amp section and most of the preamp section, and simply build tombo's buffer into the case, using the PSU, relay outputs and remote control functions. This would create a sort of "Franken-buffer" preamp, with remote control functionality, and the really low THD and nice sound. (Physically a fair bit bigger than really necessary, of course.) The PSU would probably need a voltage drop (since I built the buffers for _/0 15V, but that's no big deal, and there would be plenty of space in the chassis to do it.
I've posted a couple of photos of the Sony below. One or two small boards have been removed for visibility.
So is it a shame to sacrifice an amp that could maybe be repaired? It seems it was well-regarded when new, but I doubt it's worth any great amount of $$ now, even fixed. Anyone have thoughts on whether the Franken-project is a good idea?
Best
Nigel
I'm not sure whether this is really "Pass Labs" enough to post in this forum, but here goes anyway.
Tombo56 has a thread about his awesome input buffer (https://www.diyaudio.com/community/...ludef-sissysit-and-similar-amplifiers.382345/) and as I posted there I've made a pair and am trying them out in a (very) temporary chassis. I like them a lot, and need to fix them up in a more permanent home. A friend was throwing out his old Sony TA-S7 integrated amp, which he recently replaced because it is giving trouble (outputs cut in and out, volume sometimes suddenly jumps to full in one channel... maybe other things too...) and I rescued it from going to recycling. Initially I thought I'd have a go at fixing it (although I don't think I'd actually use it if it was working) and then thought alternatively I could maybe salvage some parts from it, and perhaps use the chassis as a home for the buffer pre.
Opening it up I found that there is a toroidal transformer, with a nice housing. It looks like the main output is +/- 18 Vac, although I'm not 100% certain I've measured the only secondary winding, since some parts of the power supply section aren't very visiv=ble, and I haven't taken it apart yet. Fiddling around a bit I found that all the remote control functioning works just fine (with a universal remote) with some of the audio circuitry disconnected, and apparently the relays switching the inputs work just fine with the pushbuttons (although so far I can't get them to work on the remote). This led me to wonder whether I could take out the power amp section and most of the preamp section, and simply build tombo's buffer into the case, using the PSU, relay outputs and remote control functions. This would create a sort of "Franken-buffer" preamp, with remote control functionality, and the really low THD and nice sound. (Physically a fair bit bigger than really necessary, of course.) The PSU would probably need a voltage drop (since I built the buffers for _/0 15V, but that's no big deal, and there would be plenty of space in the chassis to do it.
I've posted a couple of photos of the Sony below. One or two small boards have been removed for visibility.
So is it a shame to sacrifice an amp that could maybe be repaired? It seems it was well-regarded when new, but I doubt it's worth any great amount of $$ now, even fixed. Anyone have thoughts on whether the Franken-project is a good idea?
Best
Nigel
Attachments
The volume problem (and maybe others) seems to be the volume control.
Look for a bad ground solder joint, wire, etc.
Look for a bad ground solder joint, wire, etc.
I haven';t got that board up yet to take a look, but you may be right. Might be something else also; the amp is 25-30 years old, and at least one old thread here at diyaudio reports that the volume control needed replacing. Who knows.
So you'd recommend fixing, rather than Frankenstein-ing?
Well, do any easy stuff first, clean up all the pots, switches, and connectors with deoxit D5, then reevaluate the situation.
But I wouldn't repair it myself, it's not worth the trouble. You might feel differently.
But I wouldn't repair it myself, it's not worth the trouble. You might feel differently.