Bryston 4B ST problem.....?

Ebbertron · 20th December 2010, 08:59 PM

Hi everyone
I've been really impressed with the collective knowledge on these forums, so when this amp started having issues I immediately thought to inquire of you all!

I have a Bryston 4B ST amp that I got from a guy who got it from his uncle who was the original purchaser. I have no bill-of-sale, no date of sale or any other information that Bryston wants to service it under their 20-year guarantee.

the problem;

Prior to acquiring this amp, channel one "went out". Thats why I got it for so cheap (traded a technics turntable for it). I noticed that the fuse on that channel had blown. Thinking I just scored the deal of a lifetime, I threw a new fuse into it, plugged it in and turned it on. Immediately the fuse blew again.

My question;

What could be causing this? I intend to perhaps flip the power supply to the other side and see if channel 1 works to eliminate a bad power supply, but without being very tech-savy thats about the best I'll be able to do. are there any "give-aways" as to what would cause something like this to happen? Anything I should be looking for?

The boards all look good, no burns, melts, goos, anything like that, evertyhing is grounded etc.

Any suggestions, help, input etc appreciated and welcomed.

djk · 20th December 2010, 11:34 PM

Shorted outputs, drivers, or bridge rectifier.

nigelwright7557 · 20th December 2010, 11:53 PM

Possibly a shorted power supply capacitor.

Bigun · 21st December 2010, 12:10 AM

You could also replace the broken fuse with a high wattage 10R resistor and go looking for where the current is flowing (voltage drops), allowing resistor to cool down once in awhile. Maybe no a recommended method but all part of the fun!

nigelwright7557 · 21st December 2010, 12:13 AM

I would usually check the output transistors for being short circuited if the power supply was OK.

djk · 21st December 2010, 01:10 AM

"Possibly a shorted power supply capacitor."

More likely in a 3B than his 4B.

lanchile · 25th December 2010, 03:45 AM

Why all this trouble? just send it to bryston and you will get it like it just came out of factory. They will do a "FULL" check-up not just a simple fix. Bryston has the best warranty and they will make sure you get what you paid for (no matter if it was sold to you by original owner or not).

djk · 25th December 2010, 03:46 AM

"I have no bill-of-sale, no date of sale or any other information that Bryston wants to service it under their 20-year guarantee. "

lanchile · 25th December 2010, 04:18 AM

Quote:

Originally Posted by djk

"I have no bill-of-sale, no date of sale or any other information that Bryston wants to service it under their 20-year guarantee. "

Trust me!!! if it is under the 20 years warranty....They will fix it for free no matter what! and if it is more than 20 years you will not overpay for the fix. at the end you will end up with a unit not just fixed but up to specification. I am a member of Bryston forum there.Become a member there and ask all your questions and James tanner will answer all your questions for sure. Bryston Limited

PS: older units do not need the bill of sale to be repaired ! just ask James Tanner there.

djk · 25th December 2010, 04:47 AM

The last Bryston I fixed, it was cheaper for me to fix it myself than pay the freight and risk shipping damage. I also threw some mods in it while I had it open. Your mileage may vary.

20th December 2010, 08:59 PM	#1
Ebbertron diyAudio Member Join Date: Dec 2010	Bryston 4B ST problem.....? Hi everyone I've been really impressed with the collective knowledge on these forums, so when this amp started having issues I immediately thought to inquire of you all! I have a Bryston 4B ST amp that I got from a guy who got it from his uncle who was the original purchaser. I have no bill-of-sale, no date of sale or any other information that Bryston wants to service it under their 20-year guarantee. the problem; Prior to acquiring this amp, channel one "went out". Thats why I got it for so cheap (traded a technics turntable for it). I noticed that the fuse on that channel had blown. Thinking I just scored the deal of a lifetime, I threw a new fuse into it, plugged it in and turned it on. Immediately the fuse blew again. My question; What could be causing this? I intend to perhaps flip the power supply to the other side and see if channel 1 works to eliminate a bad power supply, but without being very tech-savy thats about the best I'll be able to do. are there any "give-aways" as to what would cause something like this to happen? Anything I should be looking for? The boards all look good, no burns, melts, goos, anything like that, evertyhing is grounded etc. Any suggestions, help, input etc appreciated and welcomed.

20th December 2010, 11:34 PM	#2
djk diyAudio Member Join Date: Feb 2001 Location: USA	Shorted outputs, drivers, or bridge rectifier. __________________ Candidates for the Darwin Award should not read this author.

20th December 2010, 11:53 PM	#3
nigelwright7557 diyAudio Member Join Date: Apr 2008 Location: Carlisle, England	Possibly a shorted power supply capacitor. __________________ http://www.murtonpikesystems.co.uk PCBCAD40 pcb design software.

21st December 2010, 12:10 AM	#4
Bigun diyAudio Member Join Date: Jan 2009 Location: K-W Ontario Blog Entries: 2	You could also replace the broken fuse with a high wattage 10R resistor and go looking for where the current is flowing (voltage drops), allowing resistor to cool down once in awhile. Maybe no a recommended method but all part of the fun! __________________ "The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed." Robert M Pirsig.

21st December 2010, 12:13 AM	#5
nigelwright7557 diyAudio Member Join Date: Apr 2008 Location: Carlisle, England	I would usually check the output transistors for being short circuited if the power supply was OK. __________________ http://www.murtonpikesystems.co.uk PCBCAD40 pcb design software.


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21st December 2010, 01:10 AM	#6
djk diyAudio Member Join Date: Feb 2001 Location: USA	"Possibly a shorted power supply capacitor." More likely in a 3B than his 4B. __________________ Candidates for the Darwin Award should not read this author.

25th December 2010, 03:45 AM	#7
lanchile diyAudio Member Join Date: Sep 2008	Why all this trouble? just send it to bryston and you will get it like it just came out of factory. They will do a "FULL" check-up not just a simple fix. Bryston has the best warranty and they will make sure you get what you paid for (no matter if it was sold to you by original owner or not).

25th December 2010, 03:46 AM	#8
djk diyAudio Member Join Date: Feb 2001 Location: USA	"I have no bill-of-sale, no date of sale or any other information that Bryston wants to service it under their 20-year guarantee. " __________________ Candidates for the Darwin Award should not read this author.

25th December 2010, 04:47 AM	#10
djk diyAudio Member Join Date: Feb 2001 Location: USA	The last Bryston I fixed, it was cheaper for me to fix it myself than pay the freight and risk shipping damage. I also threw some mods in it while I had it open. Your mileage may vary. __________________ Candidates for the Darwin Award should not read this author.

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