SergeModular

Sebastian Kuehnl wrote:

> Hi John,
> > That is not the case now, Rex sweats every little detail.
>
> I'll frankly ask then why you are replacing pots on four year old panels?

That's a good question. My system has seen pretty frequent studio use, plus it's
been lugged around several dozen times to gigs, jam sessions, etc. Since all the
other parts are fine I just assumed that some marginal pots surfaced in a mfr's
batch. Matt, you also had to replace a VCF pot, right? At first I thought it was
dirty but it's gotten worse - I think there's a hairline crack in the resistive
element.

One other thing that's come up, a couple years ago a VCA opamp died. Was not too
hard or expensive to replace. I was able to recalibrate the VCA by ear..... cv
rejection, gain, and audio bleed-thru @ 0 cv...

Anybody else have Serge stuff go poof?

- John P.

John Papiewski wrote:

Sebastian Kuehnl wrote:

> Hi John,
> > That is not the case now, Rex sweats every little detail.
>
> I'll frankly ask then why you are replacing pots on four year old panels?

That's a good question. My system has seen pretty frequent studio use, plus it's
been lugged around several dozen times to gigs, jam sessions, etc. Since all the
other parts are fine I just assumed that some marginal pots surfaced in a mfr's
batch. Matt, you also had to replace a VCF pot, right?

two of them, one each on different filters, but both freq controls.....which get lots of use. rex suggested
a little squirt of cleaner, which did nothing. thats why they got the boot.

At first I thought it was
dirty but it's gotten worse - I think there's a hairline crack in the resistive
element.

One other thing that's come up, a couple years ago a VCA opamp died. Was not too
hard or expensive to replace. I was able to recalibrate the VCA by ear..... cv
rejection, gain, and audio bleed-thru @ 0 cv...

Anybody else have Serge stuff go poof?

haha....certainly not "poof", but more like "grrrrrrich"....

matt

matt wilson is odyssey sounds
email: sebsi23@...
web: http://members.home.net/odysseysounds/index.htm
phone: (619) 296 9224

In a message dated 3/18/01 1:51:09 PM, johnp@... writes:

<< Anybody else have Serge stuff go poof?

Pots and op amps should not be failing after 4 years. Either the operation,
design or construction are in question with these kinds of failures.

To give some perspective on reliability, I have some experience on a
university Serge.. Photos are at Egres. The first box was a 3 panel Series
79 system (1979). The second was a four panel system, probably from around
1983. Out of 38 modules, I observed the following major problems:

1) NTO not working, no output from variable waveform, frequency only up to
16 Hz (probably an open in the frequency setting stage)
2) One blown Universal Slope Generator
3) One bad channel in UPAP
4) One nonfunctional keypad on TKB
5) One intermittent keypad on TKB

Considering the abuse that this system went through (it is located in the
beginning electronic music lab!) and its age I think the design and
construction (at the time) must be considered good.

The biggest problem I saw was with grooves cut into the pot shafts.
Apparently some knobs had come loose over time and were never tightened back
down. They still were tight enough to gouge out grooves in the metal shafts
when rotated, especially beyond their normal travel. With the grooves in
there, they could never be tightened back down to their original firmness.
Good preventative measures should be observed to prevent your own equipment
from seeing this problem.

There were of course the various noisy pots, though most of these seemed to
clear up with a few rotations.

John Loffink
microtonal@...

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