Triaxis output control odd behavior / used unit check out?

Triaxis, Quad Preamp, Stereo Power series, Recto Preamp

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davens
Bottle Rocket
Posts: 3
Joined: Wed Nov 21, 2018 9:10 pm

Triaxis output control odd behavior / used unit check out?

Post by davens » Thu Nov 22, 2018 10:07 am

New here, but not to electronics.

Just got a used Triaxis, bought as working with a noisy output control.

It's a 1900 range serial, so V2, and does not appear to have the Phat mod - theres's a rats nest of resistors and capacitors top left of the TX4 board, a little out of place on an otherwise beautiful set of boards and interconnects.

On a quick checkout, indeed one side of the output control was noisy, so I pulled the top off to clean it or remove it and order a replacement. To be sure it was operating smoothly after applying contact cleaner, I connected a DVM and for both sides turning the relevant shaft very slowly, I note a brief jump that my Fluke saw as open circuit passing around 600 ohms and 6 k ohms, but otherwise very smooth. I couldn't manage to stop turning and find a static open circuit position on either side corresponding to those approximate resistances, however slowly I turned.

Is that what should be happening or is this an output control that needs replacing?

Is there a set of checks worth doing on a used unit before getting into learning it in detail to ensure there are no hardware issues? My shop is fully equipped with audio test gear for my day job.

All I've checked so far is that the front panel controls do change things, input, output, send/ return and midi all are basically functional and clean sounds are indeed very clean.

Thank you

davens
Bottle Rocket
Posts: 3
Joined: Wed Nov 21, 2018 9:10 pm

Re: Triaxis output control odd behavior / used unit check ou

Post by davens » Sun Nov 25, 2018 9:59 pm

I should add that I've now powered it back up again and the output control is nice and quiet despite the measured steps. It seems to be dead from 0 to 1 but smooth thereafter.

I've also checked all controls and displays for expected function and ensured all LED segments are alive and well.

I'm not a tube guy so they are staying where they are.

Any comments on the odd measured output control behavior and additional checks I could do on the hardware?

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