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Bryston 3B repair gone haywire

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KV4LQ

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Bryston 3B repair gone haywire
« on: 8 Feb 2016, 01:20 am »
So I'm fixing up my grandfather's old 3B.  Nothing hard right?  Left channel works, right channel silent.  Replace a missing 22Ω resistor: It instantly melts.  Replace it again and the preamp transistor it's sitting next to: the resistor catches fire.  This is which resistor is blowing:





Why is this resistor catching fire as soon as I turn it on?  What should I replace to get this side working again?  I love these amplifiers; you normally can't hurt 'em.
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G Georgopoulos

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Re: Bryston 3B repair gone haywire
« Reply #1 on: 8 Feb 2016, 02:59 am »
hard to tell from pcb,if you can put a picture of the schematic up that would help people here heaps... :)

ok, i'll try to help blindly
is the resistor connected to a semiconductor,if so check the semiconductor if it's ok,if it checks ok and the problem persists check all other components connected/around that semiconductor...

sorry,that's all i can help with without a schematic.... :green:
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Phil A

Re: Bryston 3B repair gone haywire
« Reply #2 on: 8 Feb 2016, 03:54 am »
Quote from: G Georgopoulos on  8 Feb 2016, 02:59 am
hard to tell from pcb,if you can put a picture of the schematic up that would help people here heaps... :)

ok, i'll try to help blindly
is the resistor connected to a semiconductor,if so check the semiconductor if it's ok,if it checks ok and the problem persists check all other components connected/around that semiconductor...

sorry,that's all i can help with without a schematic.... :green:

Might be here under technical data - http://bryston.com/pages/technical.html
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Phil A

Re: Bryston 3B repair gone haywire
« Reply #3 on: 8 Feb 2016, 03:54 am »
Quote from: KV4LQ on  8 Feb 2016, 01:20 am
So I'm fixing up my grandfather's old 3B.  Nothing hard right?  Left channel works, right channel silent.  Replace a missing 22Ω resistor: It instantly melts.  Replace it again and the preamp transistor it's sitting next to: the resistor catches fire.  This is which resistor is blowing:





Why is this resistor catching fire as soon as I turn it on?  What should I replace to get this side working again?  I love these amplifiers; you normally can't hurt 'em.

PS - Welcome to AC!
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G Georgopoulos

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Re: Bryston 3B repair gone haywire
« Reply #4 on: 8 Feb 2016, 04:17 am »
Quote from: Phil A on  8 Feb 2016, 03:54 am
Might be here under technical data - http://bryston.com/pages/technical.html

Yes it's there 3B-amp,there are lot's of 22 ohm resistors there, he needs to tell us the designated resistor...

Thanks Phil A, i leave the troubleshooting to you the first in command  :green:
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Phil A

Re: Bryston 3B repair gone haywire
« Reply #5 on: 8 Feb 2016, 04:29 am »
Quote from: G Georgopoulos on  8 Feb 2016, 04:17 am
Yes it's there 3B-amp,there are lot's of 22 ohm resistors there, he needs to tell us the designated resistor...

Thanks Phil A, i leave the troubleshooting to you the first in command  :green:

If you think there is burning now, wait until I get done :lol:  My skills are probably limited to fixing a solder joint as long as I'm not chewing gum at the same time :lol:
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G Georgopoulos

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Re: Bryston 3B repair gone haywire
« Reply #6 on: 8 Feb 2016, 04:45 am »
is this genuine Bryston? or is it a knockoff? i dont want to get in trouble with Bryston for back-engineering,if James says ok,Phil be my guest at it... :thumb:
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James Tanner

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Re: Bryston 3B repair gone haywire
« Reply #7 on: 8 Feb 2016, 11:32 am »
Quote from: G Georgopoulos on  8 Feb 2016, 04:45 am
is this genuine Bryston? or is it a knockoff? i dont want to get in trouble with Bryston for back-engineering,if James says ok,Phil be my guest at it... :thumb:

Hi

I am not sure we can even comment as endorsing customers to go inside a product to fix it will bring on litigation.

james

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KV4LQ

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Re: Bryston 3B repair gone haywire
« Reply #8 on: 8 Feb 2016, 03:26 pm »
Quote from: G Georgopoulos on  8 Feb 2016, 04:45 am
is this genuine Bryston? or is it a knockoff? i dont want to get in trouble with Bryston for back-engineering,if James says ok,Phil be my guest at it... :thumb:

This is a 100% genuine Bryston 3B, albeit with some modifications, but no mods to that portion of the amp.
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werd

Re: Bryston 3B repair gone haywire
« Reply #9 on: 8 Feb 2016, 03:28 pm »
Put a bigger resistor in there and measure the voltage. What is it seeing? Or use the same one if it doesnt burn out to quick.
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KV4LQ

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Re: Bryston 3B repair gone haywire
« Reply #10 on: 8 Feb 2016, 03:30 pm »
Quote from: G Georgopoulos on  8 Feb 2016, 02:59 am
hard to tell from pcb,if you can put a picture of the schematic up that would help people here heaps... :)

ok, i'll try to help blindly
is the resistor connected to a semiconductor,if so check the semiconductor if it's ok,if it checks ok and the problem persists check all other components connected/around that semiconductor...

sorry,that's all i can help with without a schematic.... :green:

I've looked at the schematic and it's covered in 22Ω resistors.  I can't find the 417 or E55 to which it is connected.  It's a NTE E55 transistor which I assume is a preamp.  I believe the original transistor is a something 417.  It's connected between this transistor (which is mounted above the two final transistors on the heatsink) and a capacitor.  I replaced the transistor, and got the same results.
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jparkhur

Re: Bryston 3B repair gone haywire
« Reply #11 on: 8 Feb 2016, 03:30 pm »
Why don't we just send it to bryston?   spend the 150 bucks on shipping and parts and have it for another 20 years.


?

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werd

Re: Bryston 3B repair gone haywire
« Reply #12 on: 8 Feb 2016, 03:31 pm »
Do not get electrocuted. Make sure the chassis isn't hot. 
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KV4LQ

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Re: Bryston 3B repair gone haywire
« Reply #13 on: 8 Feb 2016, 03:32 pm »
Quote from: werd on  8 Feb 2016, 03:28 pm
Put a bigger resistor in there and measure the voltage. What is it seeing? Or use the same one if it doesnt burn out to quick.

I'll give that a shot.  I'm fairly busy today, so it may be a while.
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KV4LQ

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Re: Bryston 3B repair gone haywire
« Reply #14 on: 8 Feb 2016, 03:33 pm »
Quote from: jparkhur on  8 Feb 2016, 03:30 pm
Why don't we just send it to bryston?   spend the 150 bucks on shipping and parts and have it for another 20 years.


?

because I'm a junior in high school and have no money.  I know how to fix things for the most part, but I've never had a part detonate on me.
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KV4LQ

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Re: Bryston 3B repair gone haywire
« Reply #15 on: 8 Feb 2016, 03:33 pm »
Quote from: werd on  8 Feb 2016, 03:31 pm
Do not get electrocuted. Make sure the chassis isn't hot.

 :o  Yep already checked this.  It's grounded well.
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KV4LQ

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Re: Bryston 3B repair gone haywire
« Reply #16 on: 8 Feb 2016, 03:35 pm »
Quote from: James Tanner on  8 Feb 2016, 11:32 am
Hi

I am not sure we can even comment as endorsing customers to go inside a product to fix it will bring on litigation.

james

OK, take this post as 100% proof that I WILL NEVER UNDER ANY CIRCUMSTANCES SUE BRYSTON (OR ANYONE DIRECTLY ASSOCIATED WITH THE MANUFACTURE OF THIS AMPLIFIER) OR ANYONE WHO ADVISES ME TO OPEN THIS AMPLIFIER AND WORK ON IT BEFORE THE END OF THIS YEAR.  IF YOU SPAM THIS THRED TO GET LEGAL PROTECTION, THAT DOESN'T COUNT.
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jparkhur

Re: Bryston 3B repair gone haywire
« Reply #17 on: 8 Feb 2016, 03:36 pm »
Quote from: KV4LQ on  8 Feb 2016, 03:33 pm
because I'm a junior in high school and have no money.  I know how to fix things for the most part, but I've never had a part detonate on me.
We all know how to fix things etc.  But sometimes as we get older we figure out that spending some $ is better in the long run..  Keep at it..

From a HS Teacher.........
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werd

Re: Bryston 3B repair gone haywire
« Reply #18 on: 8 Feb 2016, 03:36 pm »
Or just send it to Bryston and let them fix it.  :thumb:
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werd

Re: Bryston 3B repair gone haywire
« Reply #19 on: 8 Feb 2016, 03:46 pm »
Are you just plugging it in and using the house 120 volt to power the amp while you do this?
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