Mother 32 x 3 in Eurorack - Power Issues

[Stevie Ray]

I have 3 Mother 32s in a Eurorack case powered by a Doepfer PSU3 (2A on +/- 12V and 4A on +5V).

The Mothers only use the +12V supply and according to spec. consume 3 x 230mA = 690mA. Actually on my meter it shows 605mA but I expect it depends on what's going on in the Mothers at the time (e.g use of headphone amp).

With no other modules installed in the case, I'm finding an intermittent problem where the +12V line from the PSU3 doesn't power up. The +12V LED on the A100 bus boards flashes indicating an overload. No other modules are installed right now, just the 3 Mothers.

The Mothers seem to present a large initial load on the PSU when it turns on. Maybe this is down to the bypass capacitors on the Mother's power rails charging.

Anyone else having similar problems with powering 3 Mothers, or with the Doepfer PSU3?

[Vsyevolod]

I have this problem with other modules using PSU's that are more than capable of powering them.

In my case, I just reboot. Takes about 2 seconds.

Stephen




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[Stevie Ray]

It's not a show stopper, just an annoyance. The only thing is, I can see the problem getting worse as I fill out the rest of the case.

Asked Doepfer support and their solution was to downgrade the PSU3 to the (discontinued) PSU2 which is an all linear design and not so sensitive to the initial inrush current. Not really the answer I was looking for.

If it becomes too annoying I might build a circuit to power up the three bus boards in turn using a timer circuit and some relays. I don't want to change or add another PSU as the PSU3 has plenty of capacity.