Hello, looking for personal help in rebuilding two Adcom 565 power amplifiers. I have limited experience, just a few kits from the past such as Halfer and Dynamo
Funny, I moved from Vermont about a year ago. I was near Montpelier.
Are your Adcoms having issues? High DC offset or anything like that?
Are your Adcoms having issues? High DC offset or anything like that?
Hi:
They were in a closet for about 20 years, bought new. I used them on a set of Acoustics but didn't like the sound...too bright I thought. About a month ago I plugged them in and found nasty DC offset on one and dead on another after hearing fuses blow. Took them down to Bryne Electronics in St. Johnsbury and Harry Bryn who works as an engineer at Fairbanks. He still runs an electronic store and is very experienced but told me both have the capacitor blight and that one might be saved but the other is too far gone. He does not want to get into a rebuild. I used to build Dynakits and Halfler power amps but I don't think I have the experience to tackle a 565 rebuild. I guess I am really looking for al lot of hand holding with someone local that I can go to. I think I might be able to handle stuffing Hoppe's Brain boards, but that's about it. I recently bough an osscilosocpe, a signal generator and a Fluke meter. I even have a Variac. Not in a rush over this...I have a working/restored 5500 at the moment, but wondering how more watts might sound in my system!
They were in a closet for about 20 years, bought new. I used them on a set of Acoustics but didn't like the sound...too bright I thought. About a month ago I plugged them in and found nasty DC offset on one and dead on another after hearing fuses blow. Took them down to Bryne Electronics in St. Johnsbury and Harry Bryn who works as an engineer at Fairbanks. He still runs an electronic store and is very experienced but told me both have the capacitor blight and that one might be saved but the other is too far gone. He does not want to get into a rebuild. I used to build Dynakits and Halfler power amps but I don't think I have the experience to tackle a 565 rebuild. I guess I am really looking for al lot of hand holding with someone local that I can go to. I think I might be able to handle stuffing Hoppe's Brain boards, but that's about it. I recently bough an osscilosocpe, a signal generator and a Fluke meter. I even have a Variac. Not in a rush over this...I have a working/restored 5500 at the moment, but wondering how more watts might sound in my system!
This looks like a n thread to start learning from:
The OP seems to have laid out what parts of the circuit do what. I agree with Anatech that DC offset issues seem to commonly stem from the Differential pairs (Q101, Q105, Q102 and Q106)
The OP seems to have laid out what parts of the circuit do what. I agree with Anatech that DC offset issues seem to commonly stem from the Differential pairs (Q101, Q105, Q102 and Q106)
How do you go about cleaning a 565 of dust and debris of 20 years? Compressed air doesn't;t seem to do the job. How to you physically dissemble to check each and every one of the output transistors?
Isoprophyl alcohol in a spray bottle works great. That and a toothbrush. That will also clean any flux. Apparently one thing that happens to these is the electrolytic caps leak.