Help!!!, i think i blown a cap

corleone1988 · 1728

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Offline corleone1988

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on: March 18, 2014, 09:09:19 PM
HI guys,

I have just finished setting up my Sex 2.1 ( no upgrades yet) and as soon as i turned the amp on i heard a distinct sound of a capacitor going to heaven. After waiting for awhile, the tube from B has failed to light up. Checked my voltages and a few interesting numbers popped up form some points.

6=432v 16=453v
11=412v 21=455v
15=20v 25=0v
A2=404v B2=457v
A3=20v B3=0v
A5=75v B5=393v
A6=2.5v B6=0
A7= -4.59v B7= -4.59v
A8= 2.65v B8= -4.59v

Few Questions
1: Are the voltages difference from at points 11/21, A2/B2 meant to be that large?
2: Does the 1000microF 35V electrolytic Cap from tube B needs to change ?
3: Does the brand of the capacitor needs anything specific ? ( i am planning to replace it with a generic Electrolytic Cap from the local electronics store)

PS: I checked the capacitor orientation and it is correct
« Last Edit: March 18, 2014, 09:34:55 PM by corleone1988 »



Offline Grainger49

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Reply #1 on: March 19, 2014, 12:01:11 AM
I don't have the SEX amp manual handy.  But if you think a cap gave up the ghost you should double and triple check the orientation of every electrolytic in the amp.  If it is damaged the end, one or the other, maybe both, will no longer be flat.  They bulge when they die.



Offline Paul Joppa

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Reply #2 on: March 19, 2014, 07:48:01 AM
The bad solder joint at B7 is the biggest problem.

Why do you think the 1000uF/35v capacitor has expired?

Paul Joppa


Offline corleone1988

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Reply #3 on: March 19, 2014, 12:50:53 PM
Thanks for that, reflowed A7 + A8 and B7 and B8 and i left the original cap in place and it WORKS!!!!
i thought i was that cause when i initially turned it on, sparks were jumping out at the B3 joint, but since then i never had an issue. I checked the cap as well it wasnt buldging. I jump to conclusions too fast sometimes :D