Blue Tube II Blues

Jerry Overstreet · From: Louisville Ky

Try saying that 3 times!
I'm having trouble with intermittent sound drop-outs from either a stereo side and/or one of the front end preamp channels. I'm sure some or all of the pots are causing this. Done the spraying, knob twiddling act many times. Seems OK for a time, then goes south again.

Anybody else had this problem with this unit [RT924] and found a solution short of changing all the pots? Thanks for your input. JO.

Erv Niehaus · From: Litchfield, MN, USA

Jerrry,
If you can find the pots that are causing you problems, just replace them. Tube Works equip. were noted for having scratchy pots after a while, however, they are readily available, at a very affordable price, from Genz Benz. I have replaced several over the years. No big deal.

Erv

Jon Light (deceased) · From: Saugerties, NY

The sorts of things I would open it up and look for:
--broken solder points on the pots
--a stray strand of multistrand wire bridging across the lugs of a pot
--broken solder points between pot & circuit board
--hairline cracks in circuit board that might flex the circuit open & closed
--anything at all around the effects loop jacks (if there is a loop) that might cause intermittent behavior (including the shorting contact of any shorting jack
--all of the above as applied to the input jack

You get the picture. I usually find that intermittent cutting-out kind of behavior is eventually traceable with careful observation. A continuity tester is extra helpful.

Jerry Roller · From: Van Buren, Arkansas USA

Jerry, I have two of those units with steel guitar mods. They are really nice pre-amps but the pots are very prone to get bad or at least dirty especially if not used for a while. I would be very inclined to think your problem is in a pot or pots. I think Erv has the problem pinpointed.
Jerry

Jack Stoner · From: Kansas City, MO

If you spray a pot and it either doesn't fix it or only fixes it temporarily, the Pot is bad and needs replaced.

Jerry Overstreet · From: Louisville Ky

Thanks guys. I suspect the pots as well. However, I do have it opened up and will be checking out the things Jon mentioned. Sometimes a kick upside the head brings back the loss. Might be multiple maladies!

The problem with replacing the pots is that many of them are scratchy and just rotating them can either fix or cause a problem. It might be one causing the trouble this time and another the next. For instance, the last time it was one of the efx loop pots on the back of the unit..and they are hard to get to in the case. Other times, it was a vol. control, eq pot, etc.
I guess I was just hoping there was something better than Deoxit or another method of cleaning them that I'm missing.

Erv, are the replacement pots from Genz Benz any better than the originals? I don't relish the idea of replacing all the pots, but that may be the only fix. Thanks again all JO.

[This message was edited by Jerry Overstreet on 21 September 2005 at 06:11 AM.]

Jack Stoner · From: Kansas City, MO

I don't know about the preamp pots, but I replaced the pots in my MosValve 500 power amp with new ones 5 years ago and that fixed the scratchiness in those. Spraying with cleaner was only a temporary cure.

The pots they have for MV500 were exact replacements. The volume pots were the only ones that were bad but since I had to remove the PC board to replace the two volume pots, I replaced the two presence pots at the same time.

Erv Niehaus · From: Litchfield, MN, USA

Jerry,
As far as I know, the replacements are the same as the originals but they sure took care of my problem. My unit was acting up just like yours. The volume would be down on one side of the unit and as soon as I would wiggle the knob, it would right itself.
Erv

[This message was edited by Erv Niehaus on 21 September 2005 at 07:39 AM.]

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