70s Soundcraft Series 2 Console

[man-bot]

I just picked up this series 2 console (circuit boards are dated 1976) and it looks like this board has some issues.  The PSU has been a bit funny but is operational to some degree.  When I turn the board on th VUs light up, the phantom power works and the oscillator works - but I can't seem to get the channels to pass any audio.  Regardless if I route the channel audio to any of the busses or try the direct outs... nothing.  I'm assuming its the PSU as when I first plugged it in the fuse blew and when I opened up the supply it appeared the PSU board had shorted on the heat sink inside (to the point where some of the tracks were ruined - so I jumped those with some wire).

Anyhow - I thought someone here may have some idea what my issue may be... or at least where to start looking.  Unfortunately the online manual has omitted their pages with the voltage reference through the circuit.  Just seems curious that different functions are working... but not the most inportant one.

Also some general advice on restoring this in general would be great (i.e. cleaning faders, scratchy pots)...

Hoping to make this thing work! 

 

[livingnote]

Goodness, that looks like work! If everything in the console looks like that you might really
have to dive deep...but probably the pcbs are high enough quality that you can do it pretty
well, I had this dolby reciever to do and it just got worse the more I dis-and reassembled
it, wave-soldered Pertinax and no fun at all...gave up, in the end, but what you have there
at least looks salvageable...

 

[tmuikku]

Try to take output on channel insert? They might not be normalled and not passing audio without patching.

 

[pucho812]

at any rate that PSU is due for a recap

 

[man-bot]

Well unfortunately the inserts don't work either... I decided to open up the back and was pleasantly surprised.  Thankfully the inside of the console looks pretty darn good:

I think my issue actually resides with this part at the bottom that does not look like it was stock:

It appears someone has fashioned 3 seperate PSU boards that only feed the buss channels (+/-18v going to them) - however it looks like they are supposed to have a seperate power cord to them which has been cut (there is also a hole in the side of the console there as well).  I am going to assume those things aren't set up to have 120 put to them directly and output +/- 18v... so that leaves me with 2 questions:

- what voltage do those boards need to see, and how can I determine that
- why was this mod made and can I put it back to stock

I have a feeling that if I power those I may actually have audio passing or at least use of the groups... still doesn't explain why the direct outs aren't giving audio.

Let me know your thoughts!  

 

[Denyle Guitars]

That looks almost like my 1st console. The EQ was pretty nice. Yours has input transformers, which mine did not. Cool. Looks like it has a mix of 4 band and 3 band EQs. I wonder if a previous owner made one out of two smaller consoles.

Unfortunately, my service manual went with the console a long time ago. IIRC, the psu supplied +40v & +48v. The VU lamps were wired in series in groups of 4 and fed 40v along with a regulator board near the master section. I had two psu and neither was very good.

I'd suggest a 48v linear from power one or similar and trim it down to 40v (under load). Alternatively, remove those regulator boards and use a +/- 18vdc linear along with small a +48v. I'd rewire the VU lamps parallel and replace the festoon bulbs with leds. You'll never find those bulbs.

On my psu, I increased those big caps to 10,000uf, swapped the weird Cannon AC connector for an IEC, changed the 4 pin xlr's for 5 pin (psu & console) and made a new umbilical cord. The 5th wire provided 12vdc to the VU lamps.

I'm not sure about the +/- 13vdc. Might want to see where it goes. Could be there are IC's in there that can't handle 36v.

Those molex connectors are notorious for fouling and are easy to break so take care when disassembling and cleaning.

The direct outs won't work if there's no power getting to the channels.

I do remember reading in the the service manual to clean the P&G faders in a bath of water and a tiny bit of mild soap, which I thought was odd.

 

[chrispbass]

I'd certainly try and get a copy of the schematics, if you haven't already and make sure you know what voltages to expect. At least then, you can start to work from known quantitys. You have to ask yourself why anyone would go to the trouble of fitting psu's in the desk? Is it because it was easier than fixing the main psu(it doesn't look too healthy), an upgrade or to power any additional mods? Always good to get back to basics...

Chris

 

[gar381]

Hey man-bot..

Check your email..

These are very nice desks..

Have FUN...

GARY

 

[man-bot]

Well thankfully I have the channels working now - the boards that send power to the channels were not seated correctly so with a little push all is good.  Also, after examination all of the busses have been modified so that's why they have a seperate PSU board  (different ICs, caps etc...) - still doesn't help that I don't have what was upstream of the cut power cord...

So for now the channels work but no busses.

The EQ works nicely, I'm not sure whether it was option to get both the fixed and sweep option for the EQ from the factory, but I'm happy either way that something is working!!  It does look like it would be a wise move to recap the PSU.

Thaks for the tips and help!

 

[Barks67]

Hi,

thought this may be of interest to you!

http://www.cargostudios.co.uk/photos.htm

cheers

Barks

 

[W DeMarco]

Hell yeah,  Are you the guy from the tapeop board that was lookin into this awesome console!  If so congrats, well either way...

You can find the manual at soundcrafts website under legacy or discontinued products.  Its got some good info on teching the board.  If your going to put the inserts on a pbay you'll need to half normal them so the return sees the output.  Not sure why they wouldnt be working. 

Your psu look like it was originaly for the standard eq rather than the sweep eq.  Its a dual supply, the small metal tranx is for the 48 volt supply and the large torrid is for the 40 volt supply.  I'm guessing that the extra stuff inside the board is for the swept eq channels as the use IC's and will need additional voltages, or a lot of guys modded the lights for the meters to a lower voltage so either or, or both! 

Gary I'd be interested in an email if it concerns the series 2. 

Heres our series 2 for you soundcrafts slutz


http://www.vuturevisions.com/series2.jpg

 

[W DeMarco]

Man Bot just a warning tho, be careful around here, if you start diying your gonna become an addict.

 

[gar381]

W DeMarco

I think you probably have the info I sent man-bot.
It's from my small soundcraft stash of paper.
It’s the important stuff that has been deleted from that
Discontinued products area at that special Harmon place. ;D

I knew you had a pair of series 2 desks.. very pretty!!
I got to stop by and have a look at 'em in person one
of these days!

I was a soundcraft repair guy in the late 70s early 80s
and did some work on one in Huron back in those old days.
Beautiful sounding Desk.

GARY

 

[madswitcher]

Hi man-bot

Where are you based?  That 'wierd' Connon mains connector implies that that unit was made for the BBC as they used those on all their equipment until the IEC type came along. 

As the other posters say, the main power supply is +40 volts which give a head degree of headroom - none of this +/- 15 rubbish.  The mic amps are top spec having a noise figure of 1dB or less.  IIRC as well, the faders should be P&G 10K units

I used to have one of these years ago with everything transformer coupled as the BBC specify everthing to be galavanicallly isolated - lots of good Sowter iron in there.  I would suggest a good tech (if you can't do it yourself that is) to find out what the additional psus are powering and probably why as the group line amps (general area where it seems to be) were pretty good.

The  board will probably need some TLC - recapping and a clean but should give you a very good sound.

Let us know how you get on


Mike

 

[Joechris]

BTW the fixed EQ sound much better than the sweeped ones, so use those when you record. Nice desk, nice find, enjoy.

 

[W DeMarco]

Yeah Gary,

Not sure if there were any extra goodies that i dont have.  Your welcome to come out, just let me know ahead of time so Im sure to be there.  We're off of county line road by 87.  On another note, the psu for the 24 channel board is still screwed up.  When I plug it in the voltage drop from 40 volts to 2 volts.  The other supply works fine and powers the 24 channel desk fine.  My only guess is that I fried the torrid transformer for the 40 volt rail.  It works fine with no load.

Is that even possible, torrid works til it gets a load then it just looses it?

Madswitcher I am impressed with your first post here!  Awesome topic id say...  So whats up with that console you were talking about, trannies on everything?  inserts and all?  Both of our supplies have the cannon mains as well and we're in USA. 

 

[man-bot]

Heyo - well I had a chance to look at bit more at this puppy last night and indeed the PSU boards inside the console are powering the Busses as their boards are rebuilt with 5534 ICs I believe.  As I said the channels are working though - albeit scratchy as heck!  Can I run those 5534s @ +/- 15v instead of 18?  just don't have a supply at that voltage handy...

Madswitcher - thanks for the info, nice to know that there is some proper iron on the mic inputs in there... can't wait to start laying down some tracks with it.  I'm actually in Canada just outside of Toronto, but from the sound of it the cannon connectors were used on all the boards. 

It'll definitely need some TLC, but at least the inside of it looks way better than the PSU.  Going to get it up and and running completely (i.e get the busses working, and replace 2 VUs that appear to be duffed... we'll see when I can pass some signal through the groups).

W DeMarco - nope not me from TapeOp, though it was that thread that persuaded me to go for this board. I was actually looking at a 400B when I read your posts and knew this was the better choice...  just lucky it was available on craigslist I guess!  I have done some DIY projects form here (Green Pre & 312s)... I mostly lurk though... this project has me back in the thick of it though (much to my wife's dismay)!

As I get into getting this bad boy running I'll update my progress.  It would be nicer if the channels were accessible from the top, but at least they are modular... but first things first need to have it running properly in general.

Any reccomendations when recapping - panasonics?  Also I'm going to clean some pots tonight with some non-conductive, zero residue contact cleaner... I know deoxit is reccomended but I'm not going to pull the individual channels just yet and feel better about a zero residue spray.  I guess the best way to clean the P & G fader is just water so we'll see how it goes...

 

[W DeMarco]

Sounds like its gonna be a kickass desk when your done with it.  Im sure you know to use distilled water if your gonna go that route. 

 

[man-bot]

I hope it willbe nice when done!

A few other oddities I forgot to mention:

- the boards are dated as tested 12/20/78 so I guess mine is a 78
- the non-sweepable eqs (channels 17-24) have their boards labeled channel 1-8 so it is possible they were pulled from another console (PCBs are a light green too... not darker like the other 16)
- My inputs/outputs are at more of a 90 degree angle from the top of the board (directly in behind)... not anywhere near as accessible as W DeMarco's looks... bummer there.

 

[madswitcher]

Hi again

As you say, water is the best thing to clean the P&Gs with, although try and get deionised water if you can - the sort used to fill car batteries with.  I found a soft brush or Q-tips the best and then dry them off with a hair drier or vacuum cleaner set on 'Blow'.

I used to find the motherboard connectors a bit intermittant - they are the Molex pin/pcb socket type so if you have the channels out of the frame (they come out in blocks of 4) it would be worth your while cleaning them at the same time.

You should have no problems running the 5534s off +/- 15, just a bit less headroom.  If you decide to stick with those, you might want to consider replacing them with one of the LME family.

Good luck and let us know how it goes.

Hppy listening

Mike