GFA-555 Help Please. (pics attached) - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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
Reply
 
Thread Tools Search this Thread
Old 7th August 2015, 11:27 AM   #1
CANADA is offline CANADA  Canada
diyAudio Member
 
Join Date: Aug 2015
Location: Beaverton, Ont
Default GFA-555 Help Please. (pics attached)

Hello,
I am an original (1986) GFA-555 owner, and I stupidly unplugged the speaker wire plug from one of my 18" EV subwoofers during operation. When this happened, I knew I had blown a fuse.
When I went over to the amp, I saw some smoke coming out from the center which was unusual, and when I opened it up to replace the fuse, I didn't see (or missed) any signs of damage.
Thus, I installed new a new 6amp fuse and fired her up.
Not 5 seconds after turning it on, I saw a bright orange glow and smoke coming from the main circuit board.
Upon further inspection, the 2 outside fuses were blown, and the board has now cooked some resistors and blown apart one of the black (caps?).
I've contacted Adcom, and they say there are no replacement boards available.

So, my question is......Can this be fixed, and how much would a repair like this typically cost?
Any insight would be appreciated.
Thank you so much.

Click the image to open in full size.
Click the image to open in full size.
  Reply With Quote
Old 8th August 2015, 06:45 AM   #2
diyAudio Member
 
Join Date: May 2013
looks like the board is ok, just got to go through it and replace all bad transistors and I would go ahead and replace all the capacitors except the big ones. Definitely repairable!
  Reply With Quote
Old 8th August 2015, 07:37 AM   #3
djk is offline djk
diyAudio Member
 
djk's Avatar
 
Join Date: Feb 2001
Location: USA
You must scrape all the carbon off the board, and then seal it with epoxy (or similar).

Is this a 555II?

What is the number on the board?

(AO34A)?
__________________
Candidates for the Darwin Award should not read this author.

Last edited by djk; 8th August 2015 at 08:06 AM.
  Reply With Quote
Old 8th August 2015, 10:46 AM   #4
CANADA is offline CANADA  Canada
diyAudio Member
 
Join Date: Aug 2015
Location: Beaverton, Ont
Liquid Mids:
Thank-you for the reply. It's a relief to hear that it looks salvageable. Having owned it for 25 years, and thinking I killed it.......was like losing a first born! Lol.

DJK:
The unit is a 1986 GFA-555, and the board is SMKS 394V-0. Thanks for the carbon removal tip. Makes perfect sense.

So now that I know its repairable, does anyone know anybody qualified in Toronto Ontario Canada or within reasonable proximity that can do the repairs for me? I really don't want to spend hundreds in shipping charges to and from the heart of the USA?
  Reply With Quote
Old 8th August 2015, 11:43 AM   #5
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
Try contacting anatech (a member/mod here). He's in Georgetown and is the best there is for repairs.
__________________
“The short explanation is always dull. It generally includes the word ‘just.’ The explanation only becomes beautiful when you immerse yourself in every nuance.”
  Reply With Quote
Old 8th August 2015, 12:14 PM   #6
us1070 is offline us1070  India
diyAudio Member
 
Join Date: Jan 2014
Location: Goa
To fix you will need to find and replace

You will need to find faults:

1.Shorted Transistors
2.Infinity resistance Resistor
3.Shorted Resistors
3.Blown/bulging Capacitor

Also check the output transistors if they are fine

Last edited by us1070; 8th August 2015 at 12:19 PM.
  Reply With Quote
Old 9th August 2015, 11:50 PM   #7
CANADA is offline CANADA  Canada
diyAudio Member
 
Join Date: Aug 2015
Location: Beaverton, Ont
Thanks for all the advice and tips folks!
I'll try to contact anatech, and shall update the thread when I make some progress.
Cheers!
Garry.
  Reply With Quote
Old 12th August 2015, 02:38 AM   #8
anatech is offline anatech  Canada
diyAudio Moderator
 
anatech's Avatar
 
Join Date: Jun 2004
Location: Georgetown, On
Hi Garry,
You have mail. Yes it is repairable, yes the board is damaged and requires a little work as djk mentioned. There are other problems that I'll look after as well so they don't bite you later on. Costs will depend on what we find once in there, but I will let you know.

SY, thank you for those kind words. Its appreciated.

-Chris
__________________
"Just because you can, doesn't mean you should" © my Wife
  Reply With Quote
Old 13th August 2015, 04:55 PM   #9
diyAudio Member
 
east electronics's Avatar
 
Join Date: Jan 2006
Location: Athens GREECE
Quote:
Originally Posted by us1070 View Post
To fix you will need to find and replace

You will need to find faults:

1.Shorted Transistors
2.Infinity resistance Resistor
3.Shorted Resistors
3.Blown/bulging Capacitor

Also check the output transistors if they are fine

3.Shorted Resistors
well in no case resistors will short ...They will drift or go open ...
__________________
SERVICE ΕΝΙΣΧΥΤΩΝ ΚΑΙ ΙΑΠΩΝΙΚΩΝ ΜΗΧΑΝΗΜΑΤΩΝ ΗΧΟΥ www.eastelectronics.gr
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Adcom GFA-555 eelekim Pass Labs 2 14th May 2009 03:42 PM
Gfa 555 rocketmannj Solid State 0 13th October 2008 10:50 PM
GFA-555 transformer help ben62670 Power Supplies 6 20th May 2008 02:42 AM
FS:Adcom GFA 555 and GFA 5300 trusound Swap Meet 0 13th December 2005 05:06 PM


New To Site? Need Help?

All times are GMT. The time now is 03:16 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2015 DragonByte Technologies Ltd.
Copyright ©1999-2015 diyAudio

Content Relevant URLs by vBSEO 3.3.2