onkyo A-8200 popping fuses..

marko · 14th March 2010, 02:38 PM

just bought an onkyo A-8200 as i thought it would be ideal for a little home project but to my dismay it's faulty

soon as i turn it on it pops a 2.5a 250v fuse located just after the transformer, i'm not that clued up on home audio repairs so any thoughts/ideas would be welcome!

oldmanaudio · 14th March 2010, 03:19 PM

You may have your hands full. First you must try and isolate the short. Most likely a output transistor has failed and being the main part of the power supply is on the amp board you just can't unplug it. A variac would help but I would guess you don't have one. You may want find a repair shop near you.

marko · 14th March 2010, 03:22 PM

the power supply is not on the board and is seperate so could be unpluged/desoldered i guess easy enough?

oldmanaudio · 14th March 2010, 03:31 PM

the rectifier, filter caps and regulators all live on the main amp board.

marko · 14th March 2010, 03:42 PM

so if an output has gone what's stopping me just replacing it? apart from a potential 240volt

oldmanaudio · 14th March 2010, 03:52 PM

When something shorts there can be many causes and other transistors may be taken out or a drive transistor may have failed first then caused other failures. If you just replace them it may fix it but the possiblity the new tranisitors can be taken out again.

oldmanaudio · 14th March 2010, 04:13 PM

Make sure you unplug it when working on it.

marko · 14th March 2010, 04:26 PM

Quote:

Originally Posted by oldmanaudio

Make sure you unplug it when working on it.

i thought just the caps would give a shock? there are 2 big 50v ones on the main board..

just checked the outputs and they seam to check out ok on the MM.

oldmanaudio · 14th March 2010, 04:28 PM

What do you mean they check out fine? How did you come to that conclusion?

marko · 14th March 2010, 04:33 PM

Quote:

Originally Posted by oldmanaudio

What do you mean they check out fine? How did you come to that conclusion?

i know it's not 100% conclusive but i tested all the 4 outputs for shorts and they ohmed out fine. i usually work on car amps so i'm trying to apply what knowledge i have from there. i'm keen to learn about home amps and open to all critisismn and hints/tips

14th March 2010, 02:38 PM	#1
marko diyAudio Member Join Date: May 2004 Location: donnyuk	onkyo A-8200 popping fuses.. just bought an onkyo A-8200 as i thought it would be ideal for a little home project but to my dismay it's faulty soon as i turn it on it pops a 2.5a 250v fuse located just after the transformer, i'm not that clued up on home audio repairs so any thoughts/ideas would be welcome!

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14th March 2010, 03:19 PM	#2
oldmanaudio diyAudio Member Join Date: Jan 2010 Location: P.A.	You may have your hands full. First you must try and isolate the short. Most likely a output transistor has failed and being the main part of the power supply is on the amp board you just can't unplug it. A variac would help but I would guess you don't have one. You may want find a repair shop near you.

14th March 2010, 03:22 PM	#3
marko diyAudio Member Join Date: May 2004 Location: donnyuk	the power supply is not on the board and is seperate so could be unpluged/desoldered i guess easy enough?

14th March 2010, 03:31 PM	#4
oldmanaudio diyAudio Member Join Date: Jan 2010 Location: P.A.	the rectifier, filter caps and regulators all live on the main amp board.

14th March 2010, 03:42 PM	#5
marko diyAudio Member Join Date: May 2004 Location: donnyuk	so if an output has gone what's stopping me just replacing it? apart from a potential 240volt

14th March 2010, 03:52 PM	#6
oldmanaudio diyAudio Member Join Date: Jan 2010 Location: P.A.	When something shorts there can be many causes and other transistors may be taken out or a drive transistor may have failed first then caused other failures. If you just replace them it may fix it but the possiblity the new tranisitors can be taken out again.

14th March 2010, 04:13 PM	#7
oldmanaudio diyAudio Member Join Date: Jan 2010 Location: P.A.	Make sure you unplug it when working on it.

14th March 2010, 04:28 PM	#9
oldmanaudio diyAudio Member Join Date: Jan 2010 Location: P.A.	What do you mean they check out fine? How did you come to that conclusion?