The official GroupDIY 511 Help & Support Thread

[sonic02]

The incoming voltages are
46.3v for both the 48v secondaries
-2.8v for the 24v secondaries (next to 48v)
22.9v for 24v secondaries (middle)
-1.6v foe the 16v secondaries (second from end)
15.1v for the secondaries (on the end)

 

[sahib]

Something wrong with those readings if you are reading AC.

First, you don't read negative value on AC.

Disconnect the transformer secondaries from the board and read them in isolation. Then make sure you connect them correctly.

 

[sonic02]

Sorry, took readings for DC voltages 

The AC are:
103.5v for both the 48v secondaries
13.9v for the 24v secondaries (next to 48v)
50.9v for 24v secondaries (middle)
9.5v for the 16v secondaries (second from end)
33.5v for the 16v secondaries (on the end)

 

[Harpo]

probably not.

Set your multimeter for measuring AC voltages in the meters highest voltage range setting, just in case your meters range is not auto sensing.
Take your black meter probe, connected to the meters 'COM' port, and touch the probe tip to one end of a secondary winding.
Take your red meter probe, connected to the meters 'Voltage or Ohm' port, and touch the probe tip to the other end of same secondary winding.
Read the amount of AC voltage across this secondary winding and write it down.
Repeat same procedure for the next transformers secondary windings.
Read the amount of your local AC mains voltage and write it down.
Post results (and update your forum profile with your location data. This is an intercontinental forum and not only mains voltages differ ...)

 

[sonic02]

Thanks Harpo, have measured them again with the method you suggested (apologies for my newb knowledge).

The AC are:
69.7 for the 48v secondaries
34.5v for both 24v secondaries
22.8v for the 16v secondaries

 

[Harpo]

The AC are:
69.7 for the 48v secondaries
34.5v for both 24v secondaries
22.8v for the 16v secondaries

... missing the requested local AC mains voltage reading.

You (doubtfully) seem to have scary high AC mains (back calculating from an unloaded Rondo-Müller, your AC mains will read a little above 300VAC) that hopefully will resolve to a normal 240VAC +/-10% readout by a fresh battery for your multimeter.

 

[sonic02]

WOW, unbelievable. You got it in one shot Harpo.... It was the baterry in my multimeter. All rails check out 48V, +/-24V & +/-16V. phew, so relieved, its up and running  thanks to everyone for their help, much appreciated. 
A few tips for newbs, be careful bending the regulator legs at 90 degress, they can break easy. Replace the battery in your multimeter if it shows it need replacing.

 

[G-Sun]

I think a 11space 511 rack with 2U psu case is not for me.
Are there any kits for 8-10 space with psu mounted inside?
Or a well-known route?

 

[bkbirge]

I think a 11space 511 rack with 2U psu case is not for me.
Are there any kits for 8-10 space with psu mounted inside?
Or well a known route?

I use an outboard non-racked power supply. Earlier in one of the 51x threads one of the builders built a 1 space power supply that could be slotted in but it didn't have the juice needed for the full rack.

 

[G-Sun]

I use an outboard non-racked power supply. Earlier in one of the 51x threads one of the builders built a 1 space power supply that could be slotted in but it didn't have the juice needed for the full rack.

Thanks! How big psu-case do you use?

 

[bkbirge]

I use an outboard non-racked power supply. Earlier in one of the 51x threads one of the builders built a 1 space power supply that could be slotted in but it didn't have the juice needed for the full rack.

Thanks! How big psu-case do you use?

It's pretty big, like 8x14 inch footprint or so. I got a deal on some old enclosures. But there are all kinds of boxes you can put the power supply in, heck an old cookie tin would probably work if you can get the heat dissipation to happen.

 

[Dr Gris]

I DID IT!!!!!!
My first diy exept random fixes and cables.
Many thanks to the people behind this!
Have a look at Mr Cemal' s beautiful dual PSU case.
Excuse the crappy pic.


Magnus

 

[Dr Gris]

But only two modules so far  :'(

 

[Dr Gris]

ooops, sorry 'bout the photos, tilt your heads folks...

 

[sahib]

Yeap. Entire family, we laid down on our left hand side and watched that grrreat psu case. 8)

Good stuff Magnus.

 

[Monoklang]

Hi, I have built Cemals Dual PSU and 2 x 511 racks. I have only been using one of the racks until yesterday...
I have a couple of Jeffs Vp26 connected to a couple of microphones, the phantom powered mic (ch1) doesn't work and it's a buzz all over the audio chain. The dynamic microphone (ch2) works but there is the same buzz in the background

Ok, so first:
I take those modules and put them in the other rack, everything works.

then:
I put them back, but switched the PSU/cables to see if there's something wrong with one of them, but no.

So what I understand is that the PSU is fine, cables is correct soldered and that one of the racks works perfectly with every combination of A/B PSU and cables.

That means that it's the other rack, but what...??

Today I have measured at the racks inputs, everything is correct and 16v, 24v and 48v is here.

I measure every single rail and there is 16v, 24v and 48v, I measure on the VP26 and there is 48v.

So my last attempt is that I measure the XLR's, so they have connection with the PCB, and they do...

Where does this buzz come from? And why doesn't my 48v microphones work?
I cant figure out what to do next...

Best regards
John

 

[[silent:arts]]

John, compare the ground jumpers between the working rack and the one with issues.
If your phantom power doesn't work there is a Pin1 problem (which can introduce noise and buzz)

 

[Monoklang]

Ok, so how do I compare them? I have both racks to connect Pin 1 to chassi. So where do I probe between? What amI looking for? 48v?

I have never had any problems before, so I'm a bit lost.

Thanks!
/John

 

[jsteiger]

It could also be the physical way the modules were inserted into the first rack. Maybe the card edge connectors were not lined up perfectly. 15-pin card edge into an 18-pin connector and all. I think we have heard of similar problems like this before. Worth a shot at least. 

 

[Monoklang]

Yes, but now I have very carefully seated VP25, VP26 API 512, and with dynamic microphones they work (with a tiny buzz in the background) but with phantom-microphones, not a sound. The only thing I can hear is a buzz and when I tap on the microphones bodies.

John