[BUILD] CAPI Dual VPR & 51x Floor Box PSU~Official Support Thread

All my PSU rails are ok when I test it with my empty 511 lunchbox...
I put the two DRS1R/500 in the Lunchbox and power it (I remove the JensAmp for the moment? As you guess, nothing changes  ;D)
I tested it with a slow blow fuse.
I measured the "+16V rail" and find +4,5V...

Do you think I have a problem in the lunchbox or in the PSU?

Thanks for your help

Something must be wrong with your DRS1.
Or Your +16V PSU. Hard to tell remotely ...

Are you swapping the modules while the power to the rack is on? Silly question but, you never know. You should test the +16v rail with one module at a time. If your problem is indeed a drs1r, then maybe it will help you single the faulty one out. Unless they are the verdict, I suppose. Try more slots rather than just 3 and 4. I don't know much, just trying to use common sense here. I hope it helps somehow.

Are you swapping the modules while the power to the rack is on?

Click to expand...

NO!  ;D

Next stage:

Test 1
Slot 1: DRS1 n°1
Other Slots: empty
+16V Rail = +16,7V, so it's ok...

Test 2
Slot 1: DRS1 n°2
Other Slots: empty
+16V Rail = +16,7V, so it's ok...

It means that both DRS1 are ok, isn't it?

Test 3
Slot 1: DRS1 n°1
Slot 2: DRS1 n°2
Other Slots: empty
+16V Rail = +4,5V if I use a slow blow fuse and 0V if I use fast blow fuse (which is dead)...

Did I miss something? What about the jumpers for PIN1 in the Lunchbox?  Do I have to remove it or connect it to GND, chassis? I already connect it to chassis? but maybe I'm wrong...

I also did a test to see If my +16V rail is in short-circuit with GND when I use two DRS1. No problem with that.

About the AC16 voltage: Is this a problem if both AC16 are not in phase? I mean if the two AC16 secondary transformer connection are opposite... I don't think it is the case...

I don't know what to check now, AC16 voltage are goods, all rails are goods except +16V when I use two DRS1.
:-\

I tried with all slots and I find that it's working with slot 7 to 11 and it doesn't work with slot 1 to 6...  :-\
I mean with two preamps. All still works with just one preamps.
I check for bad soldering or short-circuit and found nothing...
Any Ideas?
It's really weird. Could the SUB-D routing (or something like this) be responsible for +16V issue?
First SUB-D are for slots 1 to 6 and second for slots 7 to 11...
I am pretty sure the problem is comming from the lunchbox but I still have some doubts.
What do you think about that?

Thanks for your help 

nolivdacom said:

It's really weird. Could the SUB-D routing (or something like this) be responsible for +16V issue?
First SUB-D are for slots 1 to 6 and second for slots 7 to 11...

Click to expand...

not really, only the audio I/Os are routed, nothing PSU related.
however, do you have anything connected to the 50pin connectors?

With these pre's working in slots 7-11, what V does the 16V rail measure? I would assume it is still very low but high enough for these pre's to pass audio, possibly with very low headroom.

however, do you have anything connected to the 50pin connectors?

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No, I though it could be the problem because of the correspondence with my test (1-6, 7-11)...

With these pre's working in slots 7-11, what V does the 16V rail measure?

Click to expand...

I measured +16,7V or so.

So, If you put a module in slot 6 and one in 7, the 16V rail drops? That is very odd. Are your card edge connectors 15 pin or 18 pin? If 18 pin, could it be that the modules were not seated properly? That is about the only thing I can think of that makes sense.

So, If you put a module in slot 6 and one in 7, the 16V rail drops?

Click to expand...

Yes, it is.

My card edge connectors are 18 pin.
I plug the modules very carefully each time I did, it change nothing.
I remove PCB from rack during the last test so I could seated modules as well as possible and it was the same.

When I put modules in slots 1 and 7 (for exemple) , only the +16V rail drops (it's not the case for -16V rail and others)
I was measuring +4V and I could hear hum noise from PSU and from DRS1 24V Transformer on slots 1 only...

really odd  :-X

So... Let's say that someone theoretically got sloppy and put in C27--one of the 10000 microfarad caps--backwards.  For the sake of argument, let's say that this person was checking the voltages after powering on for the first time and the cap exploded.  Besides feeling incredibly silly and needing a new 10000 microfarad cap, would this unnamed person expect to see any other damage caused by this little mixup?  All of this is hypothetical, clearly...  No one would put one of those clearly marked caps backwards on a clearly marked PCB and not check it against the readily available photos of a populated board.  That would just be ridiculous.

Indeed that would not be fun and would maybe be VERY loud! Replacing the cap should be all that is needed.

It was indeed very loud and startling.  Luckily my face wasn't over it at the time to get hit with the volcano jet.  It was also fun to clean up.

googacky said:

It was indeed very loud and startling.  Luckily my face wasn't over it at the time to get hit with the volcano jet.  It was also fun to clean up.

Click to expand...

Theoretically....

Ha!

Well, I replaced the blown up cap today and I don't have my +16.  The LED is not lit and I'm reading zero volts at the screw terminal. Any ideas?  All the rest of the terminals check out with the DMM.

googacky said:

Well, I replaced the blown up cap today and I don't have my +16.  The LED is not lit and I'm reading zero volts at the screw terminal. Any ideas?  All the rest of the terminals check out with the DMM.

Click to expand...

Check both sides of the +16V fuse. Until you verify that the LED is working (not backwards), I would rely on the DMM to make sure all rails are up. If the fuse is good, you should start at the toroid and step your way thru the circuit to see where you first loose your V readings. You will need to consult the schemo for this.

The fuse tests fine on the DMM. I assume the LED is in properly since I'm not seeing voltage at the screw terminal, but I won't rely on it.  My diagnostic skills are rudimentary, but there's no better way to learn than fixing something you blew up!  I'll trace it down.

My problem with the +16V rail has been solved, but I have a new problem....

It turns out the +16V rail being down had nothing to do with the cap going.  If I had used my brian for a minute, I would have realized that C27 is in the -16V section of the PCB.  What was wrong is that IC5 was overtightened against the heat sink and it cut a little groove in the silicone insulator and shorted to the heat sink.  Problem solved, but...

Now the +48V fuse blew.  I loaded each of the two racks with one module to test them and they worked fine.  I loaded the rest of my modules and the fuse went on the next power up.  No phantom power was engaged.  Any idea on what to look into?  I figured I'd start by loading modules one at a time and see if I can narrow it down, but I'm all ears if there's something I should look into.

Hello,

the more often I read your post the more I think that a module has not been seated properly.
Could you please tell us which kind of rack you're using and what kind of modules?
"No phantom power was engaged" indicates that you have mic pres as modules,no?
So e.g. a vp series pre inserted in a 51x rack might short pins if not done properly without(!) phantom switches engaged on the module itself.

Hope to have helped,

Best regards,

Udo.