Adcom GFA-555

claiborne · 25th September 2007, 02:13 AM

I just got a Adcom GFA-555 with one dead channel practically given to me. I opened it up and found that both the fuses on the transistor boards on the right channel are blown. Can anyone tell me what the proper size/kind of fuses they are? I looked at the markings on the fuses and it doesn't give the type. Thank you!

-claiborne

SY · 25th September 2007, 02:27 AM

6 amp, fast blow (AGC).

It may be worth looking to see what caused them to blow...

Bigred · 25th September 2007, 02:37 AM

Yes I agree with SY; do yourself a favour and DON'T just replace the fuse and try it out with your fingers crossed. Check the physical condition of the fuse ATLEAST. If it looks like a light blow your probably safe.

claiborne · 25th September 2007, 02:44 AM

Thanks,any idea what I should take look at first? Is there a common cause of blown fuses on these amps? Something that would take out both fuses on one channel at the same time.

I gave it a very careful visual inspection and nothing looks at all damaged or burnt.

This the first solid state amp that I have tried to troubleshoot. Any quick tips you can give me would be greatly appreciated. Thanks!

-claiborne

claiborne · 25th September 2007, 02:48 AM

One fuse looks like a very clean blow but one does look worse with a little black circular burn mark on the glass. Any ideas?

Bigred · 25th September 2007, 02:51 AM

On that basis it sounds like you have a short(s). The power supply, outputs and drivers are places to start.

claiborne · 26th September 2007, 09:43 AM

I pulled the fuses out of the other channel and also rechecked the blown ones with a magnifying glass. Someone has used 10AMP 125volt fuses on both channels and the main fuse on the real panel.

Are these the correct values or has someone put the wrong ones in?

Sy,

You mentioned a 6 amp, fast blow (AGC) is this the proper rating for the main fuse also?

Once I get the proper plugs in place should I try to turn in on with a 100 watt bulb on the power cable? I am in no hurry to turn this on and I want to be a cautious as possible.

Thanks!

-claiborne

claiborne · 27th September 2007, 08:41 AM

I looked at my local parts supplier and they only had fuses rated at 250v the originals were 125v.

If the AMP and fuse type are the same is it OK to use the 250v in place of the original 125v fuse?

Thanks!!

-claiborne

djk · 27th September 2007, 10:20 AM

250V fuses are fine.

Driving certain Infinity speakers will cause the fuses to blow, and frequently the drivers too. If the fuses are the correct value the outputs are generally OK.

If someone had 10A fuses in there though, the driver transistors are probably blown, and maybe some outputs too.

Do a search on 'light bulb' and fire it up with a 75W~100W lightbulb in one side of the line.

25th September 2007, 02:13 AM	#1
claiborne diyAudio Member Join Date: Feb 2007 Location: Gulf Breeze, Florida	Adcom GFA-555 I just got a Adcom GFA-555 with one dead channel practically given to me. I opened it up and found that both the fuses on the transistor boards on the right channel are blown. Can anyone tell me what the proper size/kind of fuses they are? I looked at the markings on the fuses and it doesn't give the type. Thank you! -claiborne

25th September 2007, 02:27 AM	#2
SY diyAudio Moderator Join Date: Oct 2002 Location: Austin, TX Blog Entries: 1	6 amp, fast blow (AGC). It may be worth looking to see what caused them to blow... __________________ “Listening to records is like ****ing a picture of Brigitte Bardot.” - Sergiu Celibidache

25th September 2007, 02:48 AM	#5
claiborne diyAudio Member Join Date: Feb 2007 Location: Gulf Breeze, Florida	fuses One fuse looks like a very clean blow but one does look worse with a little black circular burn mark on the glass. Any ideas?

26th September 2007, 09:43 AM	#7
claiborne diyAudio Member Join Date: Feb 2007 Location: Gulf Breeze, Florida	Fuses I pulled the fuses out of the other channel and also rechecked the blown ones with a magnifying glass. Someone has used 10AMP 125volt fuses on both channels and the main fuse on the real panel. Are these the correct values or has someone put the wrong ones in? Sy, You mentioned a 6 amp, fast blow (AGC) is this the proper rating for the main fuse also? Once I get the proper plugs in place should I try to turn in on with a 100 watt bulb on the power cable? I am in no hurry to turn this on and I want to be a cautious as possible. Thanks! -claiborne

27th September 2007, 08:41 AM	#8
claiborne diyAudio Member Join Date: Feb 2007 Location: Gulf Breeze, Florida	Replacement fuses I looked at my local parts supplier and they only had fuses rated at 250v the originals were 125v. If the AMP and fuse type are the same is it OK to use the 250v in place of the original 125v fuse? Thanks!! -claiborne


	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

25th September 2007, 02:37 AM	#3
Bigred diyAudio Member Join Date: Jul 2007	Yes I agree with SY; do yourself a favour and DON'T just replace the fuse and try it out with your fingers crossed. Check the physical condition of the fuse ATLEAST. If it looks like a light blow your probably safe.

25th September 2007, 02:44 AM	#4
claiborne diyAudio Member Join Date: Feb 2007 Location: Gulf Breeze, Florida	Thanks,any idea what I should take look at first? Is there a common cause of blown fuses on these amps? Something that would take out both fuses on one channel at the same time. I gave it a very careful visual inspection and nothing looks at all damaged or burnt. This the first solid state amp that I have tried to troubleshoot. Any quick tips you can give me would be greatly appreciated. Thanks! -claiborne

25th September 2007, 02:51 AM	#6
Bigred diyAudio Member Join Date: Jul 2007	On that basis it sounds like you have a short(s). The power supply, outputs and drivers are places to start.

27th September 2007, 10:20 AM	#9
djk diyAudio Member Join Date: Feb 2001 Location: USA	250V fuses are fine. Driving certain Infinity speakers will cause the fuses to blow, and frequently the drivers too. If the fuses are the correct value the outputs are generally OK. If someone had 10A fuses in there though, the driver transistors are probably blown, and maybe some outputs too. Do a search on 'light bulb' and fire it up with a 75W~100W lightbulb in one side of the line. __________________ Candidates for the Darwin Award should not read this author.

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

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

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Adcom GFA-565	sourceoneaudio	Solid State	11	13th July 2011 12:43 PM
Adcom GFA-555	eelekim	Pass Labs	2	14th May 2009 03:42 PM
Adcom 2A IC for GFA 565	CompNut	Solid State	18	2nd February 2007 06:16 PM
Adcom GFA-585 went bad - calling Adcom experts	hangguy	Solid State	14	24th December 2004 08:09 PM
Adcom GFA-555 Pro	jbanneck	Solid State	2	15th February 2004 09:33 PM

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