Need advice on fixing the S.E.X 2.1 head-amp

quy lam nguyen · 2037

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Offline quy lam nguyen

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on: March 23, 2022, 10:58:50 PM
Hello,
Recently one of the resistors in my S.E.X 2.1 head-amp have exploded (as in picture A). I'm trying to find the specifications of the broken resistor in the manual to replace it with a new identical one, but I'm not sure if I've got them right. I would like to ask someone who understands well the S.E.X 2.1 head-amp about the resistor (specs, manufacturer, etc.). I want to replace the broken resistor with the exact identical component to keep the authenticity of my head-amp.
Thanks.

P/S I'm aware that the value written in the manual is 220 ohm (220 Ω 1/4W carbon composition resistors), but I'm not sure if there are any mistakes.
« Last Edit: March 23, 2022, 11:03:51 PM by quy lam nguyen »



Offline Paul Birkeland

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Reply #1 on: March 24, 2022, 04:55:55 AM
Was the amp working properly before?  That resistor dissipates no heat during operation, so for it to explode there is something very wrong.

Yes, it is a 1/4W 220 ohm carbon composition resistor.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Doc B.

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Reply #2 on: March 24, 2022, 06:38:24 AM
That particular carbon composition resistor is more fragile than other resistors and can come apart under stress of tubes being removed or inserted. In fact we no longer use those, having replaced them in our inventory with a 220 ohm carbon film resistor.

Dan "Doc B." Schmalle
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Bottlehead Corp.


Offline quy lam nguyen

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Reply #3 on: March 26, 2022, 11:01:36 PM
I'm not good at electronics. A friend of mine suggested that a 220 ohm resistor would have had a black stripe, that is why I asked about that broken resistor.

I think I have let the 0.1uF 630V capacitor touch the near-by wire, which I guess might explains the explosion of the resistor. Now I want to identify the specs of the broken resistor to replace it with a similar one. After that, I will try to fix other problems with my amp.

Thanks.

P/S: The amp was working properly, but sometimes a small pop sound appears on the right channel, and also sometimes there isn't any sound on the left channel. But that's a different problem. At the moment I want to focus on the issues of the resistor.