DIT amp schematics ADCOM GFA585 rebuild?

vincent_brient · 13th October 2008, 04:42 PM

Hi,
I am using a GFA585 for my subwoofer. I have only one channel working, but with an unstable offset. I don't have any more the other channel. A few minutes ago it completely died, some small signal transistors and resistors burnt. This one-channel GFA585 was already modified (protection removed...) so the pcb is a mess, with an offset problem and now many components burnt.

So I would like to use the existing case, +/- 90V power supply, heatsink, output transistors etc.. to build a new one-channel high power amplifier.
This amplifier used 5 pairs of bipolar transistor 2SD424 and 2SB554.
Who can give me a new and simple schematics that I could build to replace the Adcom PCB?
Or should I buy a PWM amplifier module and place it in the case? In this case I would not use the output transistors.

Vincent

ben62670 · 24th November 2008, 05:07 AM

I had rebuilt my GFA-585 input boards. They too were a mess. The caps leaked electrolite all over the boards. If the traces are not destroyed you would be best off cleaning the boards. You will need an ultrasonic cleaner, and use a 10 to 1 misture of simple green. If intereseted I can point you to my thread.
Ben

vincent_brient · 24th November 2008, 06:24 AM

Yes indeed it is probably the best way, repairing it. What is your thread? Do you have a schematics of the amplifier?

K-amps · 25th November 2008, 11:37 PM

Check out the thread for repairing the GFA-565... same schematics more or less.... same leaky caps issue...

birdyman · 09:41 PM

I found that gfa565 shematic is much diffrent than gfa585. I down loaded from googling gfa585 and forgot the link. GFA585 schema I got from internet was much better resolution, and is correct one for gfa585 than gfa565 I got from one of Adcom thread here. If you can not find it, i can email to you

Can somebody tell me what brand electrolytics they used on GFA585. My gfa 585 had really bad repairs by Frankenstain. Rt and Lt has no matching caps on value and brands.

amadork9 · 19th December 2010, 08:55 PM

Quote:

Originally Posted by birdyman

I found that gfa565 shematic is much diffrent than gfa585. I down loaded from googling gfa585 and forgot the link. GFA585 schema I got from internet was much better resolution, and is correct one for gfa585 than gfa565 I got from one of Adcom thread here. If you can not find it, i can email to you

Can somebody tell me what brand electrolytics they used on GFA585. My gfa 585 had really bad repairs by Frankenstain. Rt and Lt has no matching caps on value and brands.

hello i need a higher resolution scema for the gfa585le thanks ken

djk · 20th December 2010, 08:04 AM

Hi-Fi engine has the shop manual for the Adcom 585.

Free, may require registration.

Adcom GFA-585 | Owners Manual, Service Manual, Schematics, Free Download | HiFi Engine

amadork9 · 20th December 2010, 08:49 AM

downloaded the file gfa585 and it was the same as the one i have, couldnt read the input boards the rest was ok though

13th October 2008, 04:42 PM	#1
vincent_brient diyAudio Member Join Date: Jan 2005 Location: France	DIT amp schematics ADCOM GFA585 rebuild? Hi, I am using a GFA585 for my subwoofer. I have only one channel working, but with an unstable offset. I don't have any more the other channel. A few minutes ago it completely died, some small signal transistors and resistors burnt. This one-channel GFA585 was already modified (protection removed...) so the pcb is a mess, with an offset problem and now many components burnt. So I would like to use the existing case, +/- 90V power supply, heatsink, output transistors etc.. to build a new one-channel high power amplifier. This amplifier used 5 pairs of bipolar transistor 2SD424 and 2SB554. Who can give me a new and simple schematics that I could build to replace the Adcom PCB? Or should I buy a PWM amplifier module and place it in the case? In this case I would not use the output transistors. Vincent __________________ Vincent http://vincent.brient.free.fr/main.htm

24th November 2008, 06:24 AM	#3
vincent_brient diyAudio Member Join Date: Jan 2005 Location: France	Yes indeed it is probably the best way, repairing it. What is your thread? Do you have a schematics of the amplifier? __________________ Vincent http://vincent.brient.free.fr/main.htm

16th April 2010, 09:36 PM	#5
birdyman diyAudio Member Join Date: Jan 2010	I found that gfa565 shematic is much diffrent than gfa585. I down loaded from googling gfa585 and forgot the link. GFA585 schema I got from internet was much better resolution, and is correct one for gfa585 than gfa565 I got from one of Adcom thread here. If you can not find it, i can email to you Can somebody tell me what brand electrolytics they used on GFA585. My gfa 585 had really bad repairs by Frankenstain. Rt and Lt has no matching caps on value and brands. Last edited by birdyman; 16th April 2010 at 09:41 PM.

20th December 2010, 08:04 AM	#7
djk diyAudio Member Join Date: Feb 2001 Location: USA	Hi-Fi engine has the shop manual for the Adcom 585. Free, may require registration. Adcom GFA-585 \| Owners Manual, Service Manual, Schematics, Free Download \| HiFi Engine __________________ Candidates for the Darwin Award should not read this author.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

24th November 2008, 05:07 AM	#2
ben62670 diyAudio Member Join Date: Dec 2006	I had rebuilt my GFA-585 input boards. They too were a mess. The caps leaked electrolite all over the boards. If the traces are not destroyed you would be best off cleaning the boards. You will need an ultrasonic cleaner, and use a 10 to 1 misture of simple green. If intereseted I can point you to my thread. Ben

25th November 2008, 11:37 PM	#4
K-amps diyAudio Member Join Date: Nov 2003 Location: Indiana	Check out the thread for repairing the GFA-565... same schematics more or less.... same leaky caps issue...

20th December 2010, 08:49 AM	#8
amadork9 diyAudio Member Join Date: Dec 2010	downloaded the file gfa585 and it was the same as the one i have, couldnt read the input boards the rest was ok though

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Request for Adcom GFA-555 MkII schematics	trluser	Solid State	7	31st December 2010 05:12 AM
Need Schematics For ADCOM GFA-5802	RedCrow	Parts	6	6th November 2008 10:17 PM
RE XXX...Rebuild?	DKAudio	Subwoofers	0	16th January 2006 03:01 PM
Adcom GFA-585 went bad - calling Adcom experts	hangguy	Solid State	14	24th December 2004 08:09 PM
Schematics on the Adcom GFA-5802	K-amps	Solid State	5	5th January 2004 11:56 AM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read