Request for Adcom GFA-555 MkII schematics

trluser · 10th June 2008, 02:39 AM

Hi,

My Adcom GFA-555 MkII is blowing supply fuses on the L channel. I found some GFA-555 schematics here but they don't match what I found on the actual PCB. Even the reference part numbers are wrong.
Adcom has also used their own part numbers on the devices making it even harder.

Can someone kindly share a GFA-555 MkII schematic and parts list if they have one?

Thank you in advance.

xtaltech · 10th June 2008, 03:24 AM

You can visit http://www.audio-circuit.dk/.

trluser · 18th June 2008, 08:03 PM

Thank you for the link.

Unfortunately, they only have Adcom GFA555 and not the MkII.

The schematic and the parts designators (Qxxx) do not even match.

GEirin · 18th June 2008, 09:44 PM

Hi trluser.

Input power amplifier.

GEirin

WithTarragon · 18th June 2008, 10:25 PM

I e-mailed tech support at Adcom and they sent me a PDF within a day or so. It was good service

johnthetweeker · 19th June 2008, 06:21 AM

Quote:

Originally posted by xtaltech
You can visit http://www.audio-circuit.dk/.

Thanks, Xtaltech. It's a treasurehouse!

BLOWN · 4th October 2008, 07:17 AM

Quote:

Originally posted by trluser
Hi,

My Adcom GFA-555 MkII is blowing supply fuses on the L channel. I found some GFA-555 schematics here but they don't match what I found on the actual PCB. Even the reference part numbers are wrong.
Adcom has also used their own part numbers on the devices making it even harder.

Can someone kindly share a GFA-555 MkII schematic and parts list if they have one?

Thank you in advance.

Did you ever find the parts list?
I have a bad amp as well and suspect the input side.
Of the schematics I have seen, they were too small to read.

Can someone tell me what values correspond to the numbers on the input board capacitors?

One listing says C101 and C151. THey look like big pink square blocks. I have never seen a capacitor that was a pink square.
The do not measure like most capacitors. They both have a fixed resistance of around 1000k ohms, they don't change value on my multimeter diode setting. What does that mean? IS this really a resistor?

embrown057 · 31st December 2010, 05:12 AM

C101/151 are 1uf@100v. They are not your problem and do NOT change them unless they are shorted and I am sure they are not. They are Polycarbonate,very high quality and not easy to find. I assume from your post (big pink square blocks) you do not have much experience with electronics. I would suggest you take your amp to a good repair shop for an estamate. I am not trying to be rude but it dose not take much to turn a simple repair into a very expensive one. Do you have a working scope. function generator and DVOM? the basic equiptment?

10th June 2008, 02:39 AM	#1
trluser diyAudio Member Join Date: May 2008	Request for Adcom GFA-555 MkII schematics Hi, My Adcom GFA-555 MkII is blowing supply fuses on the L channel. I found some GFA-555 schematics here but they don't match what I found on the actual PCB. Even the reference part numbers are wrong. Adcom has also used their own part numbers on the devices making it even harder. Can someone kindly share a GFA-555 MkII schematic and parts list if they have one? Thank you in advance.

18th June 2008, 08:03 PM	#3
trluser diyAudio Member Join Date: May 2008	Not MkII Thank you for the link. Unfortunately, they only have Adcom GFA555 and not the MkII. The schematic and the parts designators (Qxxx) do not even match.

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10th June 2008, 03:24 AM	#2
xtaltech diyAudio Member Join Date: May 2004 Location: the Constitution State	You can visit http://www.audio-circuit.dk/.

18th June 2008, 10:25 PM	#5
WithTarragon diyAudio Member Join Date: Jun 2007	I e-mailed tech support at Adcom and they sent me a PDF within a day or so. It was good service

31st December 2010, 05:12 AM	#8
embrown057 diyAudio Member Join Date: May 2010 Location: Florida	C101/151 are 1uf@100v. They are not your problem and do NOT change them unless they are shorted and I am sure they are not. They are Polycarbonate,very high quality and not easy to find. I assume from your post (big pink square blocks) you do not have much experience with electronics. I would suggest you take your amp to a good repair shop for an estamate. I am not trying to be rude but it dose not take much to turn a simple repair into a very expensive one. Do you have a working scope. function generator and DVOM? the basic equiptment?

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