Adcom gfa 555 help

406vette · 11th January 2008, 07:39 PM

I have an Adcom GFA 555 with a damaged input section. I have a 555 service manual but the front end circuit board (A020 A) and related parts list don't match. I understand two different boards were used for the 555 (not counting the 555II). If anyone has information one the other configuration (my board says S394V-0) I would greatly appreciate it.

bigcrabass · 10th February 2008, 01:34 PM

I don't have an answer to your question, but I do have a 555 that I could take a look at for you. I am looking for the test points and bias voltages called out for the 555, but do not have the service manual. Does your manual cover this? I will go check the p/n of my board and report back
Bill

bigcrabass · 10th February 2008, 01:59 PM

The Part number on my 555 for the front end board is 72-2174-0-1

ben62670 · 11th February 2008, 09:59 PM

Do either of you know what the vac is coming out of the trans former. Also could you tell me the vdc on the caps.
I have the 555 manual via PDF if you need it.
Ben

pchw · 11th February 2008, 10:38 PM

Quote:

Originally posted by ben62670
Do either of you know what the vac is coming out of the trans former. Also could you tell me the vdc on the caps.
I have the 555 manual via PDF if you need it.
Ben

According to http://www.diyaudio.com/forums/showt...44#post1423844
VAC is 52-0-52, and VDC unloaded is 75.

bigcrabass · 11th February 2008, 10:53 PM

Tranformer Primary Voltage = 122.9
Secondary Voltage = 121.8
DC Votage Across Capacitor 81.2

No input signal idle

K-amps · 12th February 2008, 06:26 PM

Quote:

Originally posted by bigcrabass
Tranformer Primary Voltage = 122.9
Secondary Voltage = 121.8
DC Votage Across Capacitor 81.2

No input signal idle

Sounds about right.... for the Mk. II it was about 83vdc.

cristal63 · 29th March 2009, 03:43 PM

Quote:

Originally posted by ben62670
Do either of you know what the vac is coming out of the trans former. Also could you tell me the vdc on the caps.
I have the 555 manual via PDF if you need it.
Ben

Help me, I need of ADCOM GFA-555 , full service manual in PDF they can send me?
Thank you. Roberto

bigcrabass · 29th March 2009, 05:00 PM

Post your email address and I will email you the manual. I can't get your email from your registration.
Bill

cristal63 · 29th March 2009, 05:00 PM

Yes , you can send service manual for adcom gfa 555, at may email:

blobbulobis@inwind.it

Kindly Roberto

11th January 2008, 07:39 PM	#1
406vette diyAudio Member Join Date: Jan 2008	Adcom gfa 555 help I have an Adcom GFA 555 with a damaged input section. I have a 555 service manual but the front end circuit board (A020 A) and related parts list don't match. I understand two different boards were used for the 555 (not counting the 555II). If anyone has information one the other configuration (my board says S394V-0) I would greatly appreciate it.

10th February 2008, 01:34 PM	#2
bigcrabass diyAudio Member Join Date: Feb 2008	555 bias adjustment I don't have an answer to your question, but I do have a 555 that I could take a look at for you. I am looking for the test points and bias voltages called out for the 555, but do not have the service manual. Does your manual cover this? I will go check the p/n of my board and report back Bill

10th February 2008, 01:59 PM	#3
bigcrabass diyAudio Member Join Date: Feb 2008	Front end Board Part Number The Part number on my 555 for the front end board is 72-2174-0-1

29th March 2009, 05:00 PM	#9
bigcrabass diyAudio Member Join Date: Feb 2008	Manual for GFP 555 Post your email address and I will email you the manual. I can't get your email from your registration. Bill

29th March 2009, 05:00 PM	#10
cristal63 diyAudio Member Join Date: Mar 2009	manual request Yes , you can send service manual for adcom gfa 555, at may email: blobbulobis@inwind.it Kindly Roberto


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11th February 2008, 09:59 PM	#4
ben62670 diyAudio Member Join Date: Dec 2006	Do either of you know what the vac is coming out of the trans former. Also could you tell me the vdc on the caps. I have the 555 manual via PDF if you need it. Ben

11th February 2008, 10:53 PM	#6
bigcrabass diyAudio Member Join Date: Feb 2008	Tranformer Primary Voltage = 122.9 Secondary Voltage = 121.8 DC Votage Across Capacitor 81.2 No input signal idle

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