Vienna II Power supply

Founded in 1973, Soundcraft first made its mark with the launch of the Series 1, the first mixing console in a flightcase.

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Vienna II Power supply

Postby Logan » Sat Jun 29, 2013 9:58 pm

I'm having trouble with my Vienna II's power supply shutting down. I have two supplies, a 950 and a 900. The 950 was running everything and just lately has started shutting down, the 900 will not run the console at all. when they power off the bottom -+17 light goes off and a number of channel and half of the master lose power. Normally do you need to run the console on both supplies? There are three areas to connect the supply to the console an 8 w connection and a 10 w connection and a 16W connection, I have a cable with two connectors the 8 and 16 w ones. The tech helping me is suggesting that I try using both supplies one attached to each part of the cable. I believe my 950 supply has been altered by the guy I bought it from I'm not sure about the 900. I'm more than useless with this kind of stuff, can anybody give me any idea about how these consoles should be run power supply wise? Any tips on how to figure out what is causing the problem? Take care, Logan
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Re: Vienna II Power supply

Postby Jim Williams » Sun Jun 30, 2013 11:34 am

When Soundcraft wired a TS-24 for dual supplies, they split the buss board power feeds so one would do 1-24, the other would do the master and 26-40. If you don't split the feeds, one supply will dump into the other's outputs.
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Re: Vienna II Power supply

Postby Logan » Mon Jul 01, 2013 7:46 am

Thanks Jim, although I don't really understand the implications, I'm a twit at this stuff. I'm just trying to get enough info so the tech I use can help me deal with this, he's very good, mainly being a guitar amp guy, but has little experience with big consoles and their power supplies. I'm in the middle of nowhere and have no access to guys with more experience with consoles.
My Vienna II is a 40 channel desk with a master and a VCA strip and an 8 aux send strip and 8 channels of stereo returns groups and vca faders, in the center section separating channels 1-24 and 25-40 at the end there are four strips containing an 8 channel output matrix. Two cables feed the board from the power supply and then go to a power distro board which feed three looms. A loom powers channels 1-16 and the VCA strip. B loom powers 17-24 and the master. C loom powers 25-40 and the stereo return group VCA strips and the output matrix.

The power supply has A side (16 pin connector) and B side (8 pin connector) B side powers Loom A and B and A powers Loom C and the 7.5 volt section and I assume the 24 volt section for the meter bridge. B side is kicking out. It appears, from the notes on the schematic I got with the console, that perhaps the guy I bought it from altered the pins on the cables perhaps so that one power supply could run the entire desk. So initially I'm trying to figure out whether the vienna needed two power supplys to run, I have a 950 and a 900 but the console ran reliably, full functioned, for 3 months on just the 950 and then it started kicking out the Bside. I have had that supply looked at and it seems ok according to the guy who looked at it, a guy with experience with those supplies.
I have tried removing channels to see if there is anything that is causing the Bside to kick out but nothing that is attached to it seems to allow the console to run reliably once removed. If I disconnect the A loom entirely, from the power distro board, the console will run. Any suggestions any of you guys have would be greatly appreciated. I'm trying to get this room together and quite frankly I'm impoverishing myself and have few resources left to deal with this as I can't really bring in any work yet, getting a little desperate. Take care, Logan
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Re: Vienna II Power supply

Postby Logan » Sat Jul 27, 2013 4:12 pm

Sorry this will be a bit of a book. Firstly We have added breakout cables to the 4 Lt1083 regulators and then watched the amps being drawn with a meter. The schematics indicate that the circuits should be able to handle 6 amps. So I hooked up all the sections of the console and inserted the meter on the first reg. The power supply kicked out and 4.05 amps were shown on my meter, did the same with each of the 4 LT1083 regulators and the highest draw was 4.10 amps before it shut down., but it shut down after about 10-20 seconds each time

The power supply is really two supplies each generating some of the various voltages that are mentioned in posts above, The LT 1083's protect the various +/-17 volt rails which are what shut down. There are 3 looms which generate power around the console and there are connections for them on the power distribution board (you can see loom C at the bottom of the picture of that circuit board and looms B and A are immediately below that). I can switch the various sections of the console between looms connections and can run A and C or B and C or A and B without the power supply shutting it self down, as long as I don't use both the connections for A and B looms connections A and C or B and C run whatever is connected to them reliably. This indicates to me that no module hooked up the various looms is causing the shut down or it would shut down the supply when it was attached to one of the looms. It is the hooking something to A and B looms that causes the problem. Each loom has a +/- 17 volt section, Loom A deals with +/-17volt A and Bloom +/-17 volt B and C loom , wait for it, +/-17v C. The problem occurs when +/-17 A and B are accessed together. The 4 LT1083s that can be seen on the ps photos, control the + or - of the A and B 17volt rails, I haven't a clue what controls the 17C rail or if it exists, it isn't mentioned on the list of voltage rails in the output section of the tech specs, but it is shown as being generated by the 16 pin section of the cable and it is mentioned as powering loom C on the circuit drawings.
The A and B rails travel on the 8pin part of the cable. Ok what do I do next ;-). Take care, Logan

PS can't seem to upload the pictures but maybe my rambling scribbles will suggest something to someone. L
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Re: Vienna II Power supply

Postby AnalogStudio7 » Fri Nov 01, 2013 2:10 pm

Hi Logan,

I know this post is a little old but wanted to add some info.

You might want to contact GRS Pro Audio. They are THE console power supply guys. They work on a lot of power supplies for Soundcraft consoles and they also build new custom systems. They should be able to help you. www.grssystems.com info@grssystems.com

They have been working on my consoles and power supplies for almost 15 years now. They do excellent work.

Cheers,

Greg
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