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

[Toure14]

This is a picture of what my old seal pads and plastic washers look like overtightened....

 

[Toure14]

And 1 more shot of the over tightened hardware...learn from my mistakes people....

OOOOooooo Jeeeffff....I need some new seal pads and plastic tab things for my regulators please  ;D

 

[kante1603]

Yes,you broke them all I'd say.
Learning by doing,hahaha.......but hey,that's most likely the solution to your issues!
Think we were on a wrong track first when you told us about sparks and pops seeming to come from the mains area.
So heads up,it will work pretty soon I bet!

Best regards,thanks for the pics,very helpfull for others(!),

Udo.

 

[mulletchuck]

Toure14, host your pictures on a site like PhotoBucket or TorrentPic and paste the BB/Forum links that are autogenerated in your post.  that's how you get multiple pics in one reply. 

 

[gyraf]

Can anyone confirm that using the LM350T in a negative-voltage configuration like this is really kosher?

Sum-up of the incident.

Dual VPR & 51x Floor Box PSU, powering 51x rack containing only two Lola's. All newly built, tested to be ok.

On patching at patchbay (which may or may not have a bit of voltage potential, non-grounded computer PSU) - the -16V regulation on PSU blew, taking -16V fuse with it. Lola survived fine.

Another - also new and fresh - 51x rack + Floor Box PSU was tried, Lola's moved over in it. Worked nicely until changing patch, which killed it instantly - again the -16V regulator. Again, Lola survived the mishap.

Which made me wonder if the Floor Box PSU is adequately protected from reverse voltages, as the used LM350's are VERY hard to kill with anything else.

We changed the -16V LM350, and mounted reverse-voltage protection diodes:

2pcs 1N4007 - soldered at underside of PCB, at the power-output screw terminals. You could probably also simply screw them into the terminals together with the output power cables:

- One goes from -16V to 0V (arrow/stripe pointing towards ground/0V)
- The other goes from 0V to +16V (arrow/stripe pointing towards +16V)

The reverse protection diodes work by preventing the -16V from going above +0.6V and preventing the +16V from going below -0.6V

At re-installation in the exact same setup that killed the psu's earlier - and working hard to provoke the error - we could not recreate the fault.

In conclusion - it may be a good idea to include the reverse protection diodes.

Jakob E.

PS: Very nice project btw: I never looked closer at this before, amazed about the high quality standards..

 

[Toure14]

Can anyone confirm that using the LM350T in a negative-voltage configuration like this is really kosher?

Sum-up of the incident.

Dual VPR & 51x Floor Box PSU, powering 51x rack containing only two Lola's. All newly built, tested to be ok.

On patching at patchbay (which may or may not have a bit of voltage potential, non-grounded computer PSU) - the -16V regulation on PSU blew, taking -16V fuse with it.

Another - also new and fresh - 51x rack + Floor Box PSU was tried, Lola's moved over in it. Worked nicely until changing patch, which killed it instantly - again the -16V regulator.

Which made me wonder if the Floor Box PSU is adequately protected from reverse voltages, as the used LM350's are VERY hard to kill with anything else.

We changed the -16V LM350, and mounted reverse-voltage protection diodes:

2pcs 1N4007 - soldered at underside of PCB, at the power-output screw terminals. You could probably also simply screw them into the terminals together with the output power cables:

- One goes from -16V to 0V (arrow/stripe pointing towards ground/0V)
- The other goes from 0V to +16V (arrow/stripe pointing towards +16V)

The reverse protection diodes work by preventing the -16V from going above +0.6V and preventing the +16V from going below -0.6V

At re-installation in the exact same setup that killed the psu's earlier - and working hard to provoke the error - we could not recreate the fault.

In conclusion - it may be a good idea to include the reverse protection diodes.

Jakob E.

PS: Very nice project btw: I never looked closer at this before, amazed about the high quality standards..

Would you mind posting a pic of what you did/added?

I plan to run 2 Lolas as well with a host of other projects Im building through a pathcbay and hopefully I can kill this problem before it starts.

Thanks

 

[gyraf]

Aah - I suppose I wasn't clear: The Lola's survived fine - and are obviously well-protected, only the PSU died (edited above post). I'm not suspecting that the Lola's had any influence on the error, other than being the only units we had at hand.

Suggested mod is on the PSU, not the Lola.

If possible (the units are now in 24/7 use), I'll get the owners to post a pic (although it should be simple enough from above description)

Jakob E.

 

[gyraf]

On a side note:

The psu schematic specifies 1.5A Fast-blow fuses for the output side of the regulated voltages.

I wonder if this can get problematic when powering up racks with multiple units that all has local supply decoupling too..?

Does anyone know the rationale for using fast-blows here?

And do we need fuses at all in this place (yes, for the 48V we do, but besides that) - the regulators are very good themselves at taking action when overload occurs..

...All questions from a novice 51x'er...

Jakob E.

 

[[silent:arts]]

Hi Jakob,

while I do not really understand the blown fuse(s) with the Lolas only, thanks for the Diode protection fix.
however, I never heard of this problem before (and I'm sure there must be more Lolas out there in GDIY511 Racks and PSUs).

For the fuses, we have seen many pictures of fully loaded Racks, but no feedback / complains regarding blown fuses or other PSU problems.
(we are talking about 500+ Racks with PSUs, some PSUs driving two Racks).

Can't remember each detail, but all features / specs have been discussed here in the Lab before I did the final schematic.
So, I do not have rationale reasons for all features / specs.

 

[kante1603]

No issues here,even when driving two fully loaded 51x racks (properly sharing the 16 & 24vdc rails) from a single floorbox in a live situation.

@Volker,

I thought it was the negative voltage regs blowing and their fuses.

@Jakob,

thanks for the pointer.
But my question is still what's happening.Do you have any digital or controler stuff like MIDI,AES/EBU  etc. in your patchbay?

Just curious since short circuit diodes are implemented already.So the reverse voltage must come from somewhere......

Best regards,

Udo.

 

[gyraf]

Getting closer - there IS something in the Lola, as only one of them provokes the error.

Which means that there's little to no reason to believe it's a generic 51X-PSU problem - sorry about getting you worried about this

Will report back when I've had the time to check in-depth.

 

[kante1603]

Thanks a lot for sharing Jakob,that's very interesting!
Curious how this works out indeed.

Best,

Udo.

 

[GregNey]

Having a little trouble... any help is greatly appreciated.

Finished the build this morning, everything looks good..... except, I'm getting about half the voltage at the 48V rail (23.85V to be exact). Triple checked everything and it all looks good:
-used the correct TL783 regulator here
-am getting 54V AC off the torroid at the connector
-do not have continuity between the regulator and the case
-the correct resistors are in the correct places (150r and 5k11 are in R1 and R2 respectively)
-my rectifier bridge is oriented correctly
-all my solder joints look good...

I'm thinking it's either a bad regulator or bridge but just wanted to run it by you guys in case you had any other thoughts.

Thanks in advance, Greg

 

[kante1603]

Hi Greg,

what's the dc voltage on the bridge rectifier positive out with reference to 0v?
Would check this point first to see if the rectifier is working correct.

Does the regulator TL783 change the voltage when adjusting the pot?

Best,

Udo.

 

[GregNey]

• 24.95V on the positive side of the rectifier.
• no, it doesn't behave anything like the other 4 trimpots in the box.

 

[jsteiger]

Can you post a quick pic of the 48V rec portion of the PCB?

 

[GregNey]

pic1

 

[GregNey]

pic2

 

[GregNey]

pic3

 

[kante1603]

• 24.95V on the positive side of the rectifier.

Could be the rectifier (unlikely).Check orientation and for cold solder joints in this area.
Also what makes me wonder is that the ac from the secondary reads 54vac "....on the connector".
So that means in circuit,right?
If so then there is on open condition somewhere,the secondary should drop down to roughly 48vac when loaded.

Best,

Udo.[/list]