SEX Problems

[Aural Robert]

With my AMP lol.

So, after many years of stellar operation, at some point my SEX 2.0 amp with iron upgrade was left on for an extended period of time - I'm thinking between a week and a month. One channel stopped working so I looked under the hood and replaced a cap that was bloated.

All the resistances check out ok, but the LEDs on one C4S are both unlit. Took voltage readings and the following terminals are out of whack:

T36 should be 300vdc, reads as 377vdc
B4 should be 0, reads as -231mv
B5 should be 72, reads as -.98
B6 should be 2.5, reads as 143mv
B7 should be 0, reads as 7.2mv

Not sure where to look next for a solution. Help is appreciated as always.

Aural Robert
... to the place where they keep the imaginary diseases ...

[Paul Birkeland]

B5 should be 72, reads as -.98
B6 should be 2.5, reads as 143mv
B7 should be 0, reads as 7.2mv

Your C4S board is not properly working.  Which cap was bloated?

[Aural Robert]

Actually I found a couple of problems. During the original build I put a 220uf instead of a 47uf on one channel so that was the bloated one I replaced. Also during the original build, the 47uf was put on the other channel where there was supposed to be a 220uf (T24 - T29 specifically).

I replaced caps and have all the right caps in the right place now and the leds still do not light on one channel. I concur, something is wrong with the C4S. Pretty simple board, perhaps one of the tiny devices got toasted?

Thanks Paul.

Aural Robert
... on another time around the wheel ...

[Aural Robert]

Sorry I was away on holidays and I'm back and ready to get my amp running again.

Any advice? Or should I just ask Eileen to send me a new C4S? TIA.

Aural Robert.
... Split my caustic structure, paint my reason red ...

[Paul Birkeland]

Ordering up a fresh board will be the most convenient approach.  Other common issues are broken wires going to or coming off of the board, as well as solder joints on the board itself that may not conduct properly (though more commonly we would see excessively high voltage coming out of the board in that situation).

-PB

[fullheadofnothing]

That board is discontinued and no longer available.

[Paul Birkeland]

Ah, yes, the old 2.0 boards.  The transistors can be desoldered with a spring loaded pump and replaced, then touch up all the solder joints.

-PB

[Natural Sound]

Aural Robert, did you have the older style C4S boards that hung by the wires or the newer ones that attached to a nylon standoff? If you had the older style I might be able to help you out.

[Aural Robert]

I have the older style, but I was able to remove all the components and clean the board up. It looks ok. I`m picking up my parts on Monday and should have it back together by next weekend hopefully. If my board is dead I`ll ping you.

THANKS for the offer, much appreciated and a shining example of the camaraderie here on the forum. This is one of the reasons I`m a Bottlehead is the overwhelming support one gets when in difficulty. I am a complete electronic illiterate and my system is so freaking good I am stunned when I think I built it with my own two hands.

Aural Robert.
... agreements, advice, answers, articulate announcements ...