Samson C-Valve

Archived from groups: rec.audio.pro (More info?)

In article <Je7xd.10495$pf2.4437@fe04.lga>, Jim <no@spam.com> wrote:
>
>Now it doesnt work, he gave it to me, and i'm trying to figure it out so i
>can use it. Its a tube pre, but i think the problem may be something else
>other than the tube, when you turn it on, the output just sends a pulsing
>thump (low freqency) thats at a constant rate, the "VU" meter is maxed out
>completley and the input section doesnt light up at all, when you plug a mic
>or an instrument into it.
>
>Can someone help?

It's not a tube preamp, it's a solid state preamp with a cheesy fake tube
stage in it. This means it has seperate bipolar supplies for the solid state
stuff, and then probably a 50V supply for the B+. The B+ might even be
derived from a little switcher.

Check all the supply voltages. You'll probably find one of them is horribly
wrong.

If the supplies are good, get out the scope or the signal tracer. Start at
the beginning and work through to the end until you find the stage that is
motorboating.

But the variety of different symptoms you are seeing leads me to believe that
one of the supplies is probably bad.
--scot
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Archived from groups: rec.audio.pro (More info?)

In article <O7lxd.11240$kM2.10801@fe04.lga>, Jim <no@spam.com> wrote:
>
>Thanks for the advice, i dont own a scope anymore, and now that you tell me
>this much, i'm starting to think it may not be worth it to repair it.

It's fun. Think of it as a learning experience. And anyway, you can fix
it and sell it to some bozo on ebay for list price. Get out the schematic
and a meter and check the supply voltages.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."