risks of voltage starving // power supply questions

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lilnoah95
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risks of voltage starving // power supply questions

Post by lilnoah95 » Sun Nov 24, 2019 11:05 pm

Can I permanently damage modules by going over the maximum amperage specified by the power supply? How do i know whether specific modules would be prone to this kind of damage?


I have a doepfer a-100 diy power supply (max 1200 mA) and i only have 2 modules, one of which is a behringer neutron, which takes 1000mA, according to the manual. I'm not planning on keeping the neutron in the rack forever, but for now i want to keep it there because is saves space on my desk and makes my euro case look more full. Could overloading the doepfer power supply possibly result in damaging the neutron? Also – is there a way to test how much headroom I have?

Joe_D
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Post by Joe_D » Mon Nov 25, 2019 12:39 am

The Neutron Power Adapter puts out 100mA, but I don't think that the Neutron consumes that much (it is common and safer to use a "bigger" than needed power supply). Modular Grid lists the Neutron at 750mA -- I think that's probably what it pulls. But check with Behringer if you want to be sure; Modular Grid specs are not infallible.

What I did was make a little box for the Neutron output module and mount that at the rear of my case (I had to make an extension ribbon cable so it would reach). That lets the Neutron's power supply still power the Neturon, and retains the USB and MIDI connectivity, MIDI channel DIP switches, and headphone out (I especially find the USB connection to be useful as I run a hybrid rig; in addition to MIDI notes, I can send a CV or whatever to the Neutron's assignable output). Plus, it removes the Neutron from my case's power supply. You could go that route if you like.

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dooj88
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Post by dooj88 » Mon Nov 25, 2019 9:33 am

i'm no expert, but considering addac made a power starvation module to explore what happens when a module gets less than it needs, i think it's ok.

if you're putting more than an 80% load on your PSU, that's a whole different story. don't overload your PSU. it can pop, melt, and do other nasty things. sometimes it'll just shut off, but it's not worth the risk.

lilnoah95
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Post by lilnoah95 » Wed Nov 27, 2019 1:11 am

thanks for the responses!

Joe D, could you possibly post a picture? that sounds like a really interesting idea, and id love to get a better idea of what youre describing.

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Post by msboude » Wed Nov 27, 2019 8:11 am

While studying electronics, I learned that it's not power starvation that kills general electronics, it's over-voltage.

There are certain electronics including things like motors that can be damaged from undervoltage.. but for our purposes, a voltage sag should do no harm.

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Yes Powder
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Post by Yes Powder » Wed Nov 27, 2019 9:02 am

What about modules that have built-in voltage to step them up to a higher voltage- like Metasonix modules that regulate up to +48 or +96, or digital moudules that internally regulate down to +5V? Would this cause them to draw more current and put extra strain on the switching regulator chips?

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Mend
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Post by Mend » Wed Nov 27, 2019 10:10 am

Was reading this topic and it got me curious. Last week I think I fried my 4 Bricks rook. I'm not sure where things went sour, but here's the situation: I turned on the case and 4BR was not lighting up as usual. So I turned the case off and on again. This time. None of my modules responded. I panicked a bit and decided to turn it off again and remove the modules. Since 4BR was the first module to not power on I figured this was the culprit. But even after uninstalling 4BR the entire case wouldn't respond. I think something happened destroying both my busboard/psu (Doepfer A-100 DIY) and 4BR. I tried the other modules on another case and they seem to be working just fine.

Could this have been an 'over-voltage' situation? I'm trying to figure out what the hell happened.

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Post by msboude » Wed Nov 27, 2019 10:31 am

Did you blow the fuse on the Doepfer? Do you have a DMM to check the voltage that is being put out by the Doepfer?

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Post by Mend » Wed Nov 27, 2019 10:36 am

msboude wrote:Did you blow the fuse on the Doepfer? Do you have a DMM to check the voltage that is being put out by the Doepfer?
Possibly. Don't have a DMM. So not sure how to check.

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Post by Joe_D » Thu Nov 28, 2019 1:01 am

lilnoah95 wrote:thanks for the responses!

Joe D, could you possibly post a picture? that sounds like a really interesting idea, and id love to get a better idea of what youre describing.
Sure. The top pic shows the basic idea. The second shows the IO/power module sitting in front of the racked Neutron, not connected yet (the Neutron has the Heinakroon After Hours overlay, which has color coding and graphic separation of modules that I find makes patching and trimming quicker and easier). The bottom pic shows where it was finally installed, screwed to the back of the case with the connectors pointing left and the power switch accessible by reaching on the left side of the case. You can see the corner of the Neutron at the bottom right of the pic.

Image

To do this, you'll need a 24 pin extension ribbon cable (female to male), so you can locate the IO/power module at the rear of the case (the included cable is really short, and soldered to the board). I couldn't find one for sale, so I bought a female to female cable plus a male connector, cut off one female connector and crimped on the male connector. It was hard to find the male connector, so I'll include the link:

https://www.amazon.com/gp/product/B07YDCL3KW

Good luck with it.

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Post by jakobprogsch » Thu Nov 28, 2019 4:10 am

Mend wrote:
msboude wrote:Did you blow the fuse on the Doepfer? Do you have a DMM to check the voltage that is being put out by the Doepfer?
Possibly. Don't have a DMM. So not sure how to check.
Just visually inspect the fuse. If the piece of wire in the glass tube is broken the fuse is blown. It's also highly unlikely that you managed to destroy the busboard. There aren't really any components on there to damage (except the LEDs maybe?) and to damage the board physically you'd need WAY more power than what the PSU will deliver without blowing a fuse.

lilnoah95
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Post by lilnoah95 » Fri Nov 29, 2019 3:31 pm

Yooooo Joe D that is so sick and helpful! I totally want to recreate that on my rack, thanks so much for including the amazon link. I'm not super experienced at making DIY cables -- was crimping process easy enough once you had the parts?

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Post by Joe_D » Sat Nov 30, 2019 3:43 am

lilnoah95 wrote:I'm not super experienced at making DIY cables -- was crimping process easy enough once you had the parts?
It's much easier than soldering them IMO, especially if you have a vise of any kind. You just line them up and use some gentle force to lock the two halves together, which also pushes the pins into the wires. You don't really need the strain relief IMO; if you look at your Eurorack ribbon cables, I bet some have the strain relief, some don't.

Here's a video:



And two links specifically for Eurorack ribbon cables:

https://www.tips.modularparts.net/diy-e ... er-cables/

https://syntherjack.net/power-supply-ribbon-cable/

The last link shows it being done without a vise, but any kind of vise or clamp (like a C clamp) would make it a little easier if you have access to one (plus a few small blocks of wood to spread the force evenly on the plastic connector parts and to keep the metal tool surface from marring them).
Last edited by Joe_D on Sun Dec 01, 2019 8:13 pm, edited 3 times in total.

lilnoah95
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Post by lilnoah95 » Sat Nov 30, 2019 10:56 pm

many thanks joe !!

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