51x voltages fine until I plug in one of both 51x racks

[bobbriessinck]

Hey,

up until recently both my 51X racks & PSU worked just fine, but ever since I took one to another studio with me they've been acting weird, and now they're not working anymore. If I power up the PSU without any rack attached all the voltages measure fine (a bit above the voltages they should be at but I imagine they drop a V with load?), but once I attach a rack and power it up all the LEDs go out except for + and - 24V.
I've measured the voltages with 1 rack attached, results below:

+48V: 121mV
-16V: -304mV
+16V: 520mV
+24V: 24,96V
-24V: -24,87V
+48V: 123mV

The relays of the 500 unit click when I power the PSU on, but the LEDs don’t work, the VU of the LA500A (JLM) lights up but others don't show any sign of life besides a possible relay click.
Any idea what could be happening here? I'd like to check if there's a simple solution for this before I take the racks apart. It's just odd that they both do it with both power cables, but only 1 traveled with me outside of the studio.


I have to mention that in the other studio some of the 500s didn't work eventhough I slided them in with highest caution en checked if they were in the correct position. We were under big high pressure working against the clock and I didn't take the time to remove them from the chassis, I should've done that immediately. Then again, only one of the racks left the studio and they both experience the power drop, so my guess is that the problem lies within the PSU? At least I hope so. In coming days I'll check the 500s in a regular Fredenstein Bento to see if they're alright.

Thanks for checking this out!
Bob

 

[fallout]

You'd probably get more help/responses in the 51x PSU help thread. It's been a while since I've been inside my 51x PSU but I seem to remember that all of the power sections are fused? Perhaps pull the fuses one by one and power the PSU up and see if you could at least isolate the issue to one of the rails? At least that'd narrow down the area to troubleshoot.

The PSU is fairly simple. Perhaps one of the voltage regulators went south?

I would have pulled all of my modules and put them back in the rack one by one and see if one of them was causing the issue but like you said, it seems odd that you're having the issue with multiple racks.

 

[bobbriessinck]

You'd probably get more help/responses in the 51x PSU help thread. It's been a while since I've been inside my 51x PSU but I seem to remember that all of the power sections are fused? Perhaps pull the fuses one by one and power the PSU up and see if you could at least isolate the issue to one of the rails? At least that'd narrow down the area to troubleshoot.

The PSU is fairly simple. Perhaps one of the voltage regulators went south?

I would have pulled all of my modules and put them back in the rack one by one and see if one of them was causing the issue but like you said, it seems odd that you're having the issue with multiple racks.

Hey, thanks for your reply! I can't find any other 51x PSU thread on here... All fuses are fine, they all measure through and since the LEDs light up without any chassis connected the problem must lie within the regulators once they need to deliver amps I guess...?

Could you link me the thread your talking about? I'll repost it there. Thanks!

 

[fallout]

My suggestion was to remove the fuses one at a time and power up your rack and see if you can find the offending power rail and take it from there. I'd suspect one of the voltage regulators first. Are any of your regulators getting hotter than the rest?

Here's the 51x PSU thread:

https://groupdiy.com/threads/official-gdiy51psu-help-support-thread.36874/

 

[bobbriessinck]

My suggestion was to remove the fuses one at a time and power up your rack and see if you can find the offending power rail and take it from there. I'd suspect one of the voltage regulators first. Are any of your regulators getting hotter than the rest?

Here's the 51x PSU thread:

https://groupdiy.com/threads/official-gdiy51psu-help-support-thread.36874/

Ah, sorry, misread! I'll check that out and move this one there.