High inrush current?!? Technical people please help

Hi people,

To the Elektron staff / technical people, does the Digitone have a “high inrush current” in a situation where the power switch on the unit is turned ON, and you power on the unit and power adapter from the mains switch?

I have bought a rack power distribution unit with individual switches, one of which doesn’t work properly and the manufacturer of said unit is blaming the Digitone saying it has a ‘high inrush current and has probably welded the switch’, (without even looking at it or knowing what I’m powering).

Anyone?

Ticket?

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I wouldn’t be surprised if the Digitone had a high inrush current load. That might explain the DSP boot failure issue. It does seem to need a lot of juice to boot. However, I don’t think the load is high enough to weld your power strip’s switch, unless it’s a pretty cheap device.

…all elktron devices really prefer their own, dedicated power supplies…or individual battery solutions…

That seems highly unlikely to me, unless said switch is very low quality. I m an AV technician though not an electrician, so others might have better informed perspectives.

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Thanks people. It definitely wasn’t cheap! £200!

This is the unit:
https://www.bryant-unlimited.co.uk/SDU%20112P

The switch is actually working now all of a sudden.

But I don’t know, seems unreliable.

I say it was never welded in the first place. All electronics has a little bump in current when you turn it on, it’s physics. The amount of current needed to arc weld a switch, that is designed to arc every time it is switched on and off is considerable. That amount of current might also blow the power supply. Nah, “high inrush current” is just a convenient excuse written down on a card next to the phone at that manufacturer’s service department.

What is likely is this is just breaking in on the switch, which may not give you any more problems 'til it’s old and gray. Let’s hope so anyways.

There are inrush current limiters that chop the peaks down if needed, but the little PSU-3b doesn’t need one.

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From my limited experience studying electronic engineering , you need to soft load the power supply or else the power spike would tell the board to switch off (as it doesn’t want to be destroyed). So you should use a good ripple free power supply with surge protection as well as the official PSU. The PSU you have chosen seems to be very good.

A bit of a ramble…

Quite interesting thread, I noticed fairly recently that my breaker in the fuseboard sometimes trips when I turn all my gear on from one switch, in the past I never had any problems doing this.

I suspect some switched mode power supplies on my gear are causing the problem due to combined inrush current demand when switch is turned on.

BTW I have tested the combined draw of all my gear when powered on and it is 300w max (less than 2 amps at 220/240v) the breaker is rated at 32 amps.

I think the inrush current surge is causing unequal loading on the live and neutral lines causing the breaker to “err on the side of caution” and trip.

Right now I am just using a manual switch on the socket (very common in the UK but apparently not so common elsewhere) and occasionally I notice arcing inside the switch, obviously I am going to find a safer solution and to avoid the nuisance tripping of the breaker.

But, and this may be relevant to the OPs problem, previously I had been using remote control switches, these have a relay inside, I had a few different brands and all of them eventually failed. What I suspect had happened is that the relay(s) inside them had arced and either burnt the coil out or damaged the contacts.

It is pretty annoying and inconvenient to not be able to turn everything on from one switch, especially when dealing with the number of devices I have.

In the past when I had other gear or less gear using not using SM power supplies I never had such problems.

I need to do a bit of research to find a solution but I suspect that the culprit power supplies have saved literally a few cents/pence by omitting the thermistors on the mains input required to eliminate the problem, but this is only a theory.

FYI the unit has individual switches for each piece of gear and I turn them on one by one a few seconds apart

Hmm, well if it is designed for this usage (seems to be) and isn’t performing well then I’d be inclined to return it give the price.