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Serge PS2a calibration?
MUFF WIGGLER Forum Index -> Buchla, EMS & Serge  
Author Serge PS2a calibration?
Mood Organ
I recently noticed that two of my PS2a are way off... much closer to +/-10V instead of +/-12V. Of course, they're sealed shut. How does one go about calibrating a PS2a? How important is it?

I emailed this question to Rex and he wrote back that "The [PS2A] supplies are sealed at the factory with the outputs preset. The voltage outputs are non-adjustable."

I'm a bit puzzled by this. STS seems to make much of their calibration procedure, which is even done to match the specific power supply used.
I measured mine, purchase secondhand, and it's +12.01/-11.98
the bad producer
Have you measured it connected to panel and not connected? I wonder if it needs a load (I know nothing in particular about the PS2A BTW!)
Mine was not connected to a panel but I have measured PS4s connected and unconnected and there's little to no variance between the two.
the bad producer
I think the PS4 is a linear supply and the PS2A is a switching supply, some switching supplies need a load to operate correctly AFAIK
Ah, I didn't know that. I think the PS2a is a linear supply, though. It looks like a large switching type but I believe one of it's selling points was the fact that it's linear.

I found this on carbon111's Serge pages:

Along with the new format comes a new power supply, the PS2a. Here's the rundown of its features:

Custom made in USA for STS (not a generic Chinese "wall wart")
Precision dual regulated linear w/ low-noise audio specs (individually serialized & tested)
Heavy-duty 4-wire cable 6' interconnect cable (dual ground - instrumentation grade)
Heavy-duty 6' long detachable AC shielded line cord (w/all world line plug types available from stock)
Externally recessed 110-120/220-240 Vac / 50-60 Hz line selector slide switch
Externally recessed 5 x 20 mm fuse drawer
System "common" black banana jack (for easy interface with external equipment)
Directly mates to "M-boat with one connector (no external distribution necessary!)
Effortlessly powers up to 2 "M-boats (4 "M-class modules)
the bad producer
Oh, that is interesting, I've only seen one briefly and didn't really look at it, given it was attached to a Serge panel hihi
Mood Organ
OK, embarrassing realization:

I forgot to switch from 230V back to 110V before making the measurements. They're now reading close to expected values.

I guess the fact that they're non-adjustable explains why STS wants you to send in the power supply along with the panel for repairs and tuning.
Glad to hear that was the issue!
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