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

[googacky]

I built a VPR rack and a 51x rack.  I have mostly preamps in it and a couple compressors.  I'll check the seating of each unit later today.  It seems like it would be difficult to short to the 24V rails with a standard VPR module since there's a NC buffer pin in between, but hey, I'm a guy who put a big cap in backwards!

 

[kante1603]

I built a VPR rack and a 51x rack.  I have mostly preamps in it and a couple compressors.  I'll check the seating of each unit later today.  It seems like it would be difficult to short to the 24V rails with a standard VPR module since there's a NC buffer pin in between, but hey, I'm a guy who put a big cap in backwards!

Hahaha.....yes,but I think everybody here had some strange experiences in diy,at least you've got the balls to talk about it! ;D
But seriously one can short nearly any card edge connector contact to it's "neighbourhood" by inserting the goldfingers between two of them.It only doesn't happen when a vpr module sits in a vpr rack or a 51x module (18 pins) sits in a 51x rack.But it is possible to do it with a vpr module in a 51x rack.
I would give it a closer look,who knows....
In my builds I secured the vpr modules in my 51x racks by inserting a small but good fitting piece of plastic or so in the card edge connectors.I used some pieces of veroboard(?),the type that doesn't have copper pads of course .

Cheers,

Udo.

 

[googacky]

I guess I was thinking the problem would involve the 24V rails, but I get you. Since there is room for the edge connector to slide down, one could easily short a pin to the one below it. I'll try powering up my VPR rack with a new fuse to rule it out and then, if that passes, carefully reseat my VP modules in the 51x rack.  All my units are 15 pin at the moment, so it's possible you've guessed the problem correctly. I'll report back when I've had a chance to look. I'd like to get more fuses before experimentation begins. I only have one good one left!

 

[kante1603]

Go googacky go,good luck,hahahaha.........

Udo.

 

[googacky]

Alright.... so the plot thickens.  I'm still blowing fuses, but I've traced the problem down to my Shadow Hills Mono GAMAs.

Here's the rundown of the modules that I had loaded in the racks:

VPR Rack:
Slots 1 through 4: Shadow Hills Mono GAMAs
Slot 5: empty
Slot 6 and 7: API 512Cs
Slot 8: empty
Slots 9 and 10: API 525s

51X Rack:
Slots 1 through 4: CAPI VP26s
Slot 5: empty
Slot 6 and 7: CAPI VP28s
Slots 8 through 11: empty

I only had one spare fuse, so I thought I'd poke around a little and figure some stuff out before endangering it.  In doing so, I had my DMM set to ring continuity and discovered that on my VPR rack, pin 3 (the +16V rail) was shorted to pins 1 and 2 (chassis and PSU ground).  I figured it was might be the connector itself, so I started to pull modules to take it apart and have a look.  Once I pulled the modules, it no longer rang.  I started adding modules back and noticed that the API units were fine and having one Mono GAMA in was OK.  It's when I added a second Mono GAMA that the ringing started again.  It didn't matter which two of the four modules I have or which two slots, but every time a second Mono GAMA went in, I'd read pin 3 shorted to pins 1 and two.  I put the SH pres back in my BAE six space rack and discovered the same behavior.  With a single Mono GAMA in, no shorts, with two in, +16 rang to PSU ground.  Since the units were operating in the BAE rack, I figured that the problem must have to do with the 51x VPR rack jumpers, since this is a variable between the two racks.  I originally had all the jumpers set to connect pin 1 to chassis. 

I replaced my blown fuse with the spare, loaded all the modules except the Mono GAMAs and powered up just the VPR rack.  Everything was cool.  I reloaded the 51x rack and powered just that one on.  No problems, ruling out a short from VPR modules being loaded in a 51x rack being the problem.  Next, I moved the jumpers of slots 1 through 4 in the VPR rack from pin 1 to chassis to pin 1 to PSU ground.  I thought that the Mono GAMAs might behave fine since the BAE has this ground scheme.  I loaded a single Mono GAMA, powered up and had no problems.  I added a second, powered up and blew the damn fuse!  What is going on here?  I'm befuddled by the strange behavior of the GAMAs.  Do they short one rail to ground and only run on -16V?  Why does adding a second unit alter the behavior?  I must admit I'm pretty light on knowledge here, but I'm hoping to learn.  Any ideas?

To further muddy the waters and potentially run off on a tangent....  Two of my Mono GAMAs pass phantom power regardless of switch position.  The switch, however, tests fine with the DMM.  Confusing...  Neither of these units were used in my above tests.  I thought that their strange behavior may be contributing to the problem, so I quarantined them and loaded only the two known normally operating units for my tests.

I ordered a dozen fuses so I can experiment further when I get them and not have to worry about blowing them.  Should I have swapped all the jumpers and not just he Mono GAMA channels?

 

[jsteiger]

Hmm, interesting. I am not at all familiar with the SH stuff but know them as a very reputable manufacturer. They would not intentionally be shorting the +16V to ground. I wonder if they are using tantalum caps for local PSU decoupling in their modules. I would open them up and have a look. I believe tants short when they fail. I do not think it has anything to do with the pin-1 jumpers in the racks. It sounds like it is module related.

FWIW, I had a hard time following the pin #'s you were referring to but then it hit me that you were talking about the 7-pin Neutrik pin #'s.

Also, with the suspect SH modules out of your rack, you can probe for continuity at the modules gold fingers. See if you have continuity from gold finger 12 (+16V) to gold finger 13 (PSU gnd). You should not have a low reading or a beep.

 

[googacky]

I should have been more clear that I was testing the power connector!  It's the five pin on the VPR rack, but you get the gist.

I just ran a little experiment:  I probed edge connector pins 12 and 13 for continuity. No ring. I put one SH unit in, no ring. I put a second unit in and it rings. I tried all three othe modules against the other. All ring. I pulled the original and put another in to start and performed the same test with the same result. Any pairs ring once the second go in, so the behavior is not specific to one or two modules. All of them do it. I can't imagine they all failed in the same fashion unless something happened on initial power up of the rack. I'll make sure the units still pass signal and behave normally tomorrow when I'm back at the studio.

 

[jsteiger]

Measure the DCR from pins 12 to 13 on one (or all) of those SH units. Measure the module itself while not in the rack. Forget the rack for a moment.

 

[googacky]

Alright.... I've looked at each SH module and pins 12 and 13 do not short on any of the units when they're out of the rack.  With the DMM set to measure resistance, I'm seeing an ohm reading in the mid sixties on each unit.  I've also loaded the units back in the BAE rack and have verified that they are operating normally.  (Even to the extent that my phantom-power-stuck-on issue is no longer happening.  I suppose we can all forget the mention of that then.  Chasing ghosts...)

Does anyone else around here have Mono GAMAs in their 51x Alliance racks?

 

[jsteiger]

So you are saying that you measure 65 ohms between gold fingers 12 and 13 on the SH units? 2 units together in a rack would be 32 ohms and so on as you add more. Something seems odd about this. It also seems odd that they work in the BAE rack and not in the 51x rack.

 

[googacky]

That's what I'm saying... if I know what I'm doing!  I agree it is odd.  I have the SH units in the BAE rack right now, tested each channel and they are behaving absolutely normally.  I determined the pinout on the BAE rack and observed the same phenomena of the +16V rail ringing continuity with the PSU ground when a second unit goes in the rack.

 

[foesters]

I'm having some trouble with powering up my PSU.
I keep blowing my AC connector input fuse and I don't exactly know what's the problem.

Any thoughts on what could be wrong?

 

[foesters]

tried another fuse.
Still blowing it...

 

[Harpo]

tried another fuse.
Still blowing it...

tried a piece of string. too short.
tried another piece of string. still too short...

You couldn't be more unspecific.
What is your local AC mains voltage ? (updating your profile with at least your continent might give us a clue).
What is your fuse rating and fusing characteristic ? (mA / tt,t,m,,f,ff)
Is the fuse blowing with load connected ?

 

[foesters]

tried another fuse.
Still blowing it...

tried a piece of string. too short.
tried another piece of string. still too short...

You couldn't be more unspecific.
What is your local AC mains voltage ? (updating your profile with at least your continent might give us a clue).
What is your fuse rating and fusing characteristic ? (mA / tt,t,m,,f,ff)
Is the fuse blowing with load connected ?

Oh sorry!
I'm located in Belgium. So it's 230volts.
The fuse is the T2.5AL250V one, like the manual said.

I'm at step 36-37 in the manual where you need to power on the PSU.
The moment I pop it on, it blows the fuse.

I based my wiring on the info Kante1603 provided in post 3.

 

[kante1603]

I based my wiring on the info Kante1603 provided in post 3.

Hello,

I have compared my pics to yours,the wiring seems to be correct,at least at the screw terminal.
You've got your kit from volker (silent arts),right?
Looks like you have a dead short somewhere.
Check for solder blobs and good joints as usual.
After that I would start to look at the transformer first to see if it is o.k..
Lift the wires temporarily from the screw terminal as well as the primary wires.Check if all primaries and secondaries for dcr.Under no circumstance should there be a reading at zero ohms.Check them amongst each other too.
Sadly I don't have mine here to cross-check/compare it to yours,it's "working" on my f.o.h. at the moment.

Hope that helps,

Udo.

 

[Harpo]

I'm located in Belgium. So it's 230volts.

..and from your pic you wired the 1st. (115VAC) primary winding to 230VAC instead of a series connection. Ouch.

The fuse is the T2.5AL250V one, like the manual said.

...for US 115VAC mains. Use half of this rating for european 230VAC mains.

Exchange the white wire from the 1st.primary winding with the white wire from the 2nd.primary winding at your mains voltage selector switch and hope, your transformer survived this abuse. Hope as well, the fuse blew faster than your caps and voltage regulators, seeing double of expected secondary input voltage before the fuse decided, this might not be healthy and better to commit suicide.

Good luck.

 

[kante1603]

I'm located in Belgium. So it's 230volts.

..and from your pic you wired the 1st. (115VAC) primary winding to 230VAC instead of a series connection. Ouch.

Auaaahhhh.....

 

[foesters]

Exchange the white wire from the 1st.primary winding with the white wire from the 2nd.primary winding at your mains voltage selector switch and hope, your transformer survived this abuse. Hope as well, the fuse blew faster than your caps and voltage regulators, seeing double of expected secondary input voltage before the fuse decided, this might not be healthy and better to commit suicide.

Good luck.

Ow damn stupid me...
So i just change the 2 white primary wirings and switch the fuse to a 1.5a/230v fuse, and hope for the best ?

 

[Harpo]

Ow damn stupid me...
So i just change the 2 white primary wirings and switch the fuse to a 1.5a/230v fuse, and hope for the best ?

Half of 2.5A is ??? ...
For your mains wiring, this little scetchup might help you a little...