The amplifier puts out between 10 and 20 volts on out put ,blows the breaker.
Changed all the caps on control board. changed op amp ,the 4 ref transistors with zener diodes.(Adcom 2)TP301 and TP201 do adjust with R143, but still no joy.
Any suggestions much appreciated
Changed all the caps on control board. changed op amp ,the 4 ref transistors with zener diodes.(Adcom 2)TP301 and TP201 do adjust with R143, but still no joy.
Any suggestions much appreciated
It could be the common problem with the leaking caps on the input board, like in the 585. If so, you have to clean the board (and the opamp and its socket) extremely thoroughly. I suggest you look at the threads here about that, to determine if that might be your problem and if so how to correct it.
The link I gave in this thread should be a good start:
http://www.diyaudio.com/forums/solid-state/205483-adcom-gfa-585-known-issue-guide-needed.html
The link I gave in this thread should be a good start:
http://www.diyaudio.com/forums/solid-state/205483-adcom-gfa-585-known-issue-guide-needed.html
gfa 565
I have cleaned the board thoroughly. But I will try again.
I will post the result. Thanks once again
I have cleaned the board thoroughly. But I will try again.
I will post the result. Thanks once again
Read the link before doing it again (and mainly the whole link included within the link). There are several specific things that you have to attend to, when doing the cleaning.
Seems to be a lot of problems with these Adcoms. either that, or there are millions of them out there.
gfa565
Thanks for giving me more information. All my life I have worked with electronics but now retired and the nogging does not work the same.I will let you know what happened
Thanks for giving me more information. All my life I have worked with electronics but now retired and the nogging does not work the same.I will let you know what happened
still though construction is good and amps sound nice ...
work on the Ic see if correct voltages are present i have no experience with this model still i have been repairing 6 of 545 with similar problems mostly related on the ic
work on the Ic see if correct voltages are present i have no experience with this model still i have been repairing 6 of 545 with similar problems mostly related on the ic
In the case of the 565 and 585, at least, there was a bad batch of 220 uF electrolytic capacitors that were used (which were from a still-highly-respected capacitor manufacturer. So, not Adcom's fault. These amplifiers were designed by an excellent team of now-famous designers, and are truly excellent, except for this known problem.)
The defective 220 uF caps eventually leak and unfortunately they almost always cause havoc with the DC servo circuits, which are very sensitive to small changes in resistance between some of the traces and opamp pins, which should normally be isolated from each other.
adcom gfa 565
I have taken the board out completely and will immerse it in a sonic bath to clean.Any other suggestion and what liquid to use in the bath much appreciated.
I have taken the board out completely and will immerse it in a sonic bath to clean.Any other suggestion and what liquid to use in the bath much appreciated.
I forget the details of the cleaning solution composition. I believe that is covered in the links.
The last place I worked at we washed 1978 PC boards from an Ampex VTR in the dishwasher using ElectroSol and then dried them in a commercial food dehydrator. The boards looked and operated like new.
All the capacitor acid I've run into is water soluble so the dishwasher should be good. You DEFINITELY have to get rid of the acid. Last week I had a nearly invisible acid track that shorted a regulated (7905) -5V supply to an unregulated +8 which of course went to +7.5, ruined some new caps and at least 2 linear ICs. The acid short measured 1.3 ohms.
G²
I would also pay special attention to the IC socket, and its PCB holes. I would probably remove it, suck all of the solder out of the holes that I could, clean thoroughly, then install a new socket.
You really should read the ENTIRE set of linked threads, though. There were also some people who had to remove some of the solder mask.
You really should read the ENTIRE set of linked threads, though. There were also some people who had to remove some of the solder mask.
adcom gfa 565
Thank you gentlemen. I have a sonic jewellery cleaner.I am going to put dishwasher liquid and clean. I will tell you what happened, It will take me a day or so.
Thank you gentlemen. I have a sonic jewellery cleaner.I am going to put dishwasher liquid and clean. I will tell you what happened, It will take me a day or so.
Click the GO ADVANCED button. Then, click the little down-arrow that is to the right of the "Paper Clip" icon. (The paper clip icon is to the right of the "smiley face" icon, in the top row.) A window will open. Click a "Browse" button. Etc.
A Metcal iron with an STTC-126 tip is excellent for clearing the plate through holes once the cap is removed. The tip partly fits INTO the hole and heats it better than stainless needles. Back out the soldering iron a small amount and use the solder sucker to vacuum it out. The temperature control is Mil Spec and will not overheat but will maintain the temp. I've not tried the new 80 Watt units but the old 40 Watt units are good for nearly everything.
G²
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