Doepfer

I've just replaced a Doepfer PSU2 with a Doepfer PSU3 in my Doepfer case. I installed it successfully using install threads from Muff's, and by referring to my other case which already has a PSU3 factory installed.

All the modules are working with the new PSU3 but when I power on or off the case, all the LEDs on my modules flash briefly. This does not occur if I move the same modules to my case with the factory installed PSU3. I am nowhere near the maximum power consumption. Seems like maybe a power surge? Is this OK, or is there something I may have missed when installing the new PSU?

Thanks!

> I've just replaced a Doepfer PSU2 with a Doepfer PSU3 in my
> Doepfer case. I installed it successfully using install threads
> from Muff's, and by referring to my other case which already has
> a PSU3 factory installed.
>
> All the modules are working with the new PSU3 but when I power on
> or off the case, all the LEDs on my modules flash briefly. This
> does not occur if I move the same modules to my case with the
> factory installed PSU3. I am nowhere near the maximum power
> consumption. Seems like maybe a power surge? Is this OK, or is
> there something I may have missed when installing the new PSU?
>
> Thanks!

The way how the voltages turn on and off is different for switching supplies
(like PSU3) and linear supplies (like PSU2). It depends upon the module in
question how it responds during power on as at this moment the circuits are
not yet in the normal working state. It depends upon how fast the voltages
turn on, the sequence (+12V and -12V turn on with a small delay in between)
and the individual slope (the voltages turn not on nstantaneously). But I'd
expect that the two PSU3 behave in the same way. You may swap the two PSU3
to find out if it has to do with the PSU or the wiring. To be on the safe
side I'd measure the output voltages. They should read +12.0V and -12.0V
with not more than 1% tolerance (i.e. 11.0 - 12.1). But if all modules work
as they should after power on I think everything is OK.

Best wishes
Dieter Doepfer

Just in case people don't realise there was a keyboard slip there, I'm sure Dieter meant to type 11.9 not 11.0. For it to have a 1% tolerance the range should be 11.9-12.1 volts.

I suppose that it has to do with the discharging of the capacitors inside
the switching power supply modules used in the A-100PSU3.

Best wishes
Dieter Doepfer

> Measured the output voltages from the +12, 5 and -12 spades on
> the bus boards. All within .1v, and no sign of any spike at power
> on/off. So looking good I guess.
>
> Weirdly, I noticed that in my other case with factory-installed
> PSU3, the LEDs will flash at power off/on when it hasn't been
> turned on in a while, but if I turn on/off again a few times they
> stop flashing. So who knows? As long as my case is safe. Thanks
> again for help!