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Sudden issues with case/psu/modules, any help welcome
MUFF WIGGLER Forum Index -> Eurorack Modules  
Author Sudden issues with case/psu/modules, any help welcome
franktropez
Hi, I'm suddenly having issues with my eurorack setup, any help or thoughts would be much appreciated. I'll try to give as much info as possible and try to clearly outline the issues.
I have a 84hp Erica Synths skiff powered by their external 2.5A psu with the following modules and layout:


Both the utemps and uO_C are slightly different versions but have been working without any issues for a couple of months.
The rack has been in this configuration for a couple of weeks without any issues, the latest addition was the doepfer mixer.

Tonight I decided to put hemispheres on my uO_C. So I powered down the case, took out the uO_C, put a little bit of rubber padding under the module to prevent any shorting weirdness and successfully put the firmware on the module.
While I was doing this I noticed the utemps hadn't powered on, weird but whatever. So I reboot the case and it still doesn't come on. I check the cabling but can't find any issues. Now I notice that Plonk also doesn't properly boot; there's lights but no screen etc. Oh dear.

So I decide to empty out the rack and put the utemps in first to see if it comes on, no luck, nothing on the screen. I do notice a very very faint burnt electronics smell. It's so faint though that I even question if it's just my imagination. There was never any smoke or anything obviously.
I power down the rack again and accept that the utemps needs repairing or replacing. Put in plonk but in the top left position and it powers up without issues, quite a relief.
So I put in the entire bottom row of modules (as in the modulargrid screenshot with plonk in its original position) and decide to power on to check if everything is still ok. Plonk has issues again. I take out Plonk, power back on and now Stages is behaving weirdly.

At this point I decide to stop and go to ask for help on here as I'm incredibly worried about damaging my modules or case by troubleshooting in this manner.
Any ideas on what could have happened? Did I short something out while uploading hemispheres to the uO_C? Could this somehow have damaged the uTemps and also the case's busboard?
How should I proceed and what are the odds of doing further damage by trying to narrow down where the issue(s) lie?

I hope this post is somewhat readable and coherent, english is not my first language and I'm not so great at written communication, sorry.
Would really appreciate any help or thoughts, thanks in advance.

One last thing; While emptying the case I checked every modules power cable orientation on the board as well as the module just to be sure but everything was the way it should be.

EDIT:
As the uTemps was the first module to show any sign of trouble I sent the person who built it a message. They replied incredibly quickly and asked to check if the teensy board led lit up. When I went to check it the uTemps booted up again as if nothing happened.
Gandalf
Could be a power-up issue. As the amount of load on a power supply increases it an affect the speed at which the regulated rails reach their target levels. Some modules, especially digital ones might have a problem if one of the rails doesn't get up to level within a reasonable timeframe.
As well as module loads, this delay can also be a result of ambient temperatures and other factors.
Assuming it is safe to hot-plug a module you could try powering up with some modules disconnected and then plugging in the other modules (this is better done with a power-on delay module connected to one or modules or busboards.
Foghorn
One thing that is sometimes an issue, is the rails coming up to voltage at the same time, or at the same speed.
This probably doesn't have anything to do with the problem that you are having franktropez.

But, I had several Doepfer A-134-1 panning modules that burned up their
V-2164(VCA) chips when the PSUs did not come up to voltage at the same rate.
The V-2164 chip can not tolerate the presence of one rail without the other power supply rail.
This was driving me crazy as I kept replacing the IC chip, and it kept burning out.
I just thought I would bring this up to illustrate the complexity of some problems with cases and PSUs.

franktropez, I assume that you have looked at the current load that your modules present to the case.
I think it is a good idea to have a large amount of overhead, like 1-1/2 times, between the advertised PSU current limit and what you are consuming.
What is advertised is not always what the PSU can source.

It might help if you provide the link to your case on modulargrid, and make sure it is a public case.

One other thing, you can include the info at the bottom of a screen snip which shows current consumed by the modules. That is almost as useful as the link.

Foghorn
jamos
I saw a recent post in which someone had a similar problem because the 5v line was shorted to 12 v due to a break in the ribbon cable... no reason to think that's the issue here but worth checking if you're completely stuck.

Good luck -
alfa
Dear Foghorn
About problems with PSU & 2164.
Have a look on AS2164 where these problem is mostly solved:
http://www.alfarzpp.lv/eng/sc/AS2164.php
franktropez
First of all; thanks to everyone who replied. I haven't had the chance to check out any of your suggestions yet

Foghorn wrote:
One thing that is sometimes an issue, is the rails coming up to voltage at the same time, or at the same speed.
This probably doesn't have anything to do with the problem that you are having franktropez.

But, I had several Doepfer A-134-1 panning modules that burned up their
V-2164(VCA) chips when the PSUs did not come up to voltage at the same rate.
The V-2164 chip can not tolerate the presence of one rail without the other power supply rail.
This was driving me crazy as I kept replacing the IC chip, and it kept burning out.
I just thought I would bring this up to illustrate the complexity of some problems with cases and PSUs.

franktropez, I assume that you have looked at the current load that your modules present to the case.
I think it is a good idea to have a large amount of overhead, like 1-1/2 times, between the advertised PSU current limit and what you are consuming.
What is advertised is not always what the PSU can source.

It might help if you provide the link to your case on modulargrid, and make sure it is a public case.

One other thing, you can include the info at the bottom of a screen snip which shows current consumed by the modules. That is almost as useful as the link.

Foghorn


Regarding the load; should be well within specs, the psu should be able to deliver 2.5A, total power consumption of the modules comes to 1.33A.
Here's a link to the case:
https://www.modulargrid.net/e/racks/view/1006684

Good call on the ribbon cable, jamos, I'll try replacing it as soon as I hit another snag with a module.
Gandalf
franktropez wrote:
First of all; thanks to everyone who replied. I haven't had the chance to check out any of your suggestions yet

Foghorn wrote:
One thing that is sometimes an issue, is the rails coming up to voltage at the same time, or at the same speed.
This probably doesn't have anything to do with the problem that you are having franktropez.

But, I had several Doepfer A-134-1 panning modules that burned up their
V-2164(VCA) chips when the PSUs did not come up to voltage at the same rate.
The V-2164 chip can not tolerate the presence of one rail without the other power supply rail.
This was driving me crazy as I kept replacing the IC chip, and it kept burning out.
I just thought I would bring this up to illustrate the complexity of some problems with cases and PSUs.

franktropez, I assume that you have looked at the current load that your modules present to the case.
I think it is a good idea to have a large amount of overhead, like 1-1/2 times, between the advertised PSU current limit and what you are consuming.
What is advertised is not always what the PSU can source.

It might help if you provide the link to your case on modulargrid, and make sure it is a public case.

One other thing, you can include the info at the bottom of a screen snip which shows current consumed by the modules. That is almost as useful as the link.

Foghorn


Regarding the load; should be well within specs, the psu should be able to deliver 2.5A, total power consumption of the modules comes to 1.33A.
Here's a link to the case:
https://www.modulargrid.net/e/racks/view/1006684

Good call on the ribbon cable, jamos, I'll try replacing it as soon as I hit another snag with a module.

It is not a question of whether the power supply can meet and exceed the load requirements of the system, it is a question of whether it can handle the start-up inrush current which can be VERY large for a few moments. Some power supplies will see this as a fault condition and shutdown, others will 'try' and get working as soon as possible which result in not only the power rails 'taking time' to get within the required limits for stable operation, but also get them all there at the same time. The -12V usually has the least load and so can, in these situations reach maximum voltage almost instantaneously, while the much heaver loaded +12V rail could take a few seconds to get within the working limit. This can cause initialising conditions for a module to fail, circuits to latch up because they are not correctly powered. And if the 5V also suffers as a consequence, it can cause digital circuits to latch-up and microcontrollers to fail to start
Foghorn
Gandalf wrote:



It is not a question of whether the power supply can meet and exceed the load requirements of the system, it is a question of whether it can handle the start-up inrush current which can be VERY large for a few moments.

That is what I was awkwardly trying to say, and is especially true with microprocessor based modules (Tides, Plaits, Plonk, Wavetable VCO)



alfa wrote:
Dear Foghorn
About problems with PSU & 2164.
Have a look on AS2164 where these problem is mostly solved:


I guess you are talking about this:
........................... "AS2164 is internally protected in situations where negative supply is turned OFF."
That is good to see.
I'm glad I bought 2 dozen of the earlier V2164 chips. d'oh!

Actually I gave up on the Doepfer modules and bought some EMW panning modules, and some Ladik A-410 "Pan/Mix" modules which work perfectly.
I might have to explore the crossfading/mix functions of these modules.
The Pan/Mix modules are neat when set for panning and fed a stepped random signal or even noise as a pan control CV.

Well, I guess I digressed.

Foghorn
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