Help! Wierd broken power supply?

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Sirius Topic
Learning to Wiggle
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Help! Wierd broken power supply?

Post by Sirius Topic » Tue Mar 17, 2020 4:50 pm

Hi People,

im quite new to the modular game and i dont really have any special knowledge in electrics. ive ran in a wierd problem that seems pretty random to me:

- whenever i use my modular synth, after a short period of time, something is overloading (i think) and some modules stop working.
- the tones, that are still produced dont really react to voltage changes (e.g. my befaco evenvco only reacts in the slightest way to changes on the octave switch).
- even if nothings patched i am able to hear the oscillator (when the gain is cranked up)
- when using an unbalanced audio cable at my synths output and connect it to my mixer (behringer xenyx), the problem occurs faster
- when using a balanced cable or headphones the synth seems to work fine (the overloads still happen sometimes), but still, from time to time, there is some noise (without me touching or doing anything), that is waaaay louder than the regular output level (and threatens to break my speakers).

my setup:
- a diy eurorack case, bought from ebay with:
- a built in psu (there is no label, so i dont know the brand and i also dont know how many ampere it provides, which is problematic i think)
- doepfer a-190-2
- doepfer a-139-2
- befaco evenVCO
- dreadbox eudemonia
- waldorf mod1

sorry for not being too specific. i dont dare trying over and over again to find a pattern, because im afraid i could damage the modules.
i hope someone can help me here! :)

thank you and have a nice day!

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Yes Powder
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Re: Help! Wierd broken power supply?

Post by Yes Powder » Tue Mar 17, 2020 4:55 pm

This should probably have gone in the Eurorack board.
But as long as we're here, can you post a photo of the power supply? Some more knowledgeable wigglers might be able to tell you what you have, and if that's what's causing problems.

Sirius Topic
Learning to Wiggle
Posts: 2
Joined: Tue Mar 17, 2020 2:41 pm

Re: Help! Wierd broken power supply?

Post by Sirius Topic » Tue Mar 17, 2020 5:28 pm

this is my power supply...

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Re: Help! Wierd broken power supply?

Post by Agawell » Tue Mar 17, 2020 5:55 pm

yeah it does sound like it could be the power supply - I don't recognise it but someone might - there are some power supplies that only power 500mA on each rail, although these are not usually the type pictured and together with the power draw from the modules - I just checked on modulargrid to see the draw from those modules - its about 500-600mA on each rail, rough calculation - so this could be the problem - if you create a rack on modulargrid you can see the power consumption just below the rack - it may not be 100% correct but it's usually good enough

if you haven't already fried your modules then you will almost definitely not damage them doing this:

taking them all out then test as follows

leave the modular on for a lot longer than the usual time to failure before switching off and proceeding with the next test

test each module on it's own

- if there is still a problem with more than one of the modules it is probably an issue with the psu as opposed to overloading - possibly try the doepfer modules first - they had lowish power consumption iirc

- if there is a problem with only one of the modules - then it may be this module that is the problem - remove this from the test set for now and proceed *

if each module passes the test individually then adding one module at a time then adding another module and repeating

when you hit the problem - you will have an indication of what the problem is - is it that you are trying to draw too much power or something else

If you can get all the modules except the mod1 (it's the most power hungry iirc) running without a problem, you may want to take them all out again and start with the mod1 and repeat the exercise - this way you can get a rough idea of the power consumption that the psu is happy with

I'm assuming that all the modules are factory built - the even vco is also available as a kit - if it is diy then this may be an issue too - so maybe this last if

*if you are in this situation then check the power cable - make sure the red stripe is correct at both the module and the busboard - I've had reversed connectors before now

on the module the header may be keyed - or marked as to where the red stripe should be - if not it is probably down

busboard is keyed

check cables themselves are correct - there should be a bump (the key) on one side - red stripe must be to the left of the key when looking at it with the key at the bottom and the cable at the top

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