official GDIY51PSU Help & Support Thread

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Jeff,

a lot of work went into the Voltage frame for the voltage regulator trimmers :-[
me (I mean Harpo) calculated a lot on that.
thus, a 4 x 16V is a no go :eek:

however ;)
stuffing the 24V rails with the same resistor values like the 16V would do it :D
the 48V has enough juice for 22 Microphones too in my opinion ...

should we announce the PSU failure indicator PCB yet? ;D
 
Haha! Yes, I thought it would be that simple. I also agree with the 48V. Boy, the VPR spec of 5mA per channel is kind of a joke isn't it? I wonder what they were thinking?

Yes, I think you should announce the PSU failure board. It is a very, very cool addition to the already cool product line.  8) ;D :D ;) :)
 
jsteiger said:
Would it be as simple as changing out R11, R21, R13 and R23 to match the values for the standard 16V parts of the circuit?

That, and you need to supply rather more cooling. As it is the 24V regulators have to drop ~3V more than the 16V ones; when rewired for 16V but still fed from a 24VAC winding they have to drop ~11V more.

From another perspective: if you take 24VAC in to get 16VDC out, your regulator has to dissipate about as much as your load. So for a fully-loaded 500 rack each of the regulators has to dissipate ~23W, or ~46W for the pair. Not impossible, but not trivial for a TO-220 reg either.

EDIT: looked at the data sheet, and "not trivial" was a bit of an understatement. Max junction temperature for a LM350T is 125C, max junction-to-case thermal resistance is 4K/W. Dissipating 23W drops 92K over that, so even if you find an infinite heat sink at full load your ambient temperature cannot be higher than 33C. Good luck achieving that in a typical rack.

EDIT #2: Ah, I see you were talking about "If someone has the proper toroidal trafo". I assumed that that would be the one Volker specced in the first post of this thread, but I suppose it could also mean a transformer with, say, [email protected] plus a Phantom winding. While that does change the power dissipation issue, I would still opt for something simpler (like Keith's board).

jsteiger said:
Boy, the VPR spec of 5mA per channel is kind of a joke isn't it? I wonder what they were thinking?

Once upon a time, when the Phantom voltage was mainly used to bias the capsule, the P48 spec (DIN 45596) stated that 2mA was the maximum allowed current draw. I'd say the VPR folks were simply following orders the standard.

JDB.
 
with the ongoing discussion of powering more than one rack in mind, (which i'm of course hoping to do  8) ), would there be a problem strapping ammeters on the supply rails that i'm not seeing?  this could give a far better handle on how much juice was left for consumption.
 
Hi All

I built a supply with 2 PSU boards ready for the next rack. The supply has fuses on each rail rated for the regulators. We loaded the rack with 4 VP25, 2 X-12MK500, 2 API512, 3 API 550b. Then ran white noise signal though all and had no heat issues. My heat sink is a 2x2x1/8 aluminum angle running the length of the board then bolted to the steel case. The fuse's are cheap insurance against my bad Diy projects, hot swap mishaps and you can take your eye off the ammeter.

JamesW
 
JamesW said:
Hi All

I built a supply with 2 PSU boards ready for the next rack. The supply has fuses on each rail rated for the regulators. We loaded the rack with 4 VP25, 2 X-12MK500, 2 API512, 3 API 550b. Then ran white noise signal though all and had no heat issues. My heat sink is a 2x2x1/8 aluminum angle running the length of the board then bolted to the steel case. The fuse's are cheap insurance against my bad Diy projects, hot swap mishaps and you can take your eye off the ammeter.

JamesW
Cool stuff JamesW. Got any porn pics for us??  :)
 
JamesW said:
Hi All

I built a supply with 2 PSU boards ready for the next rack. The supply has fuses on each rail rated for the regulators. We loaded the rack with 4 VP25, 2 X-12MK500, 2 API512, 3 API 550b. Then ran white noise signal though all and had no heat issues. My heat sink is a 2x2x1/8 aluminum angle running the length of the board then bolted to the steel case. The fuse's are cheap insurance against my bad Diy projects, hot swap mishaps and you can take your eye off the ammeter.

JamesW

Hi James, you are not alone ;D
my personnel will include two PSUs too ;D
and I know of a few others ...

SHOW US PICS

I tell you a secret:
a PSU supporting PCB will be available soon.
5 fuses
5 be colored LEDs, showing green for working / red for "fuse broken" / nothing for Power Rail is dead
 
Ptownkid said:
will that be an add on for the current PSU?
yep.
8pin Molex of the PSU PCB to the LED / fuses PCB,
8pin Molex from the PSU PCB to the 7 pin XLR PSU connector.

have to think about where grounding would be best, but that is easy.
 
Yes guys, it is very sweet!!! Cemal has crafted up a nifty little circuit for this. He sketched it out while watching his his son play at the park!  :D

Maybe we will call this little PCB "A Walk In The Park".  ;D
 
unlikekurt said:
I realize this is lame, but would someone be kind enough to post part numbers for the screw terminals?
It would be greatly appreciated.
Thanks
Like this one at Digi-Key? It's the 10 position .156" pitch. 281-1440-ND
 
[silent:arts] said:
...the 10n Cs over the bridge rectifiers are not needed. if you like them - stuff them, if you don't like them - leave them out ;D ...
So, what are the advantages or disadvantages to using (or not using) these ceramic caps? Learn me something.  8)

Best, Jeff
 
jsteiger said:
[silent:arts] said:
...the 10n Cs over the bridge rectifiers are not needed. if you like them - stuff them, if you don't like them - leave them out ;D ...
So, what are the advantages or disadvantages to using (or not using) these ceramic caps? Learn me something.  8)

Best, Jeff
Fitting these high voltage ceramic snubber caps (at whatever value required and with or without series resistors) might help for a better/less buzzy or ringing supply, depending on mains transformer secondary inductance and type of rectifying diodes used.
Some reading here on snubbers http://www.hagtech.com/pdf/snubber.pdf
 
Jeff, can't find the original posts anymore.

as far as I remember:
it started with Moby missing them in the Poor Man PSU,
and ended with JDB who didn't liked them once I putted the snubbers in the 51x PSU.
I just decided to leave the footprints in, and let the user decide.
different people, different opinions, and people here always want options ;D
and no, I didn't calculated anything for them.

Harpo, thanks for that link. will be interesting to read.
 

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