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Author Topic: I need help  (Read 4865 times)

Dusk Bennett

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I need help
« on: January 18, 2011, 12:31:06 PM »

So, really long story kept brief, I got pulled into an a situation where I was asked to reconnect the PSU's of a Neve 8128 this week. I have never done this before.

At first I determined that the (original?) DC supply cables were not long enough so I subsequently swapped them out with longer/thicker 16/3. (I was led to believe by a few tech here in town that this was OK.)

Most of the lines I was able to make good sense out of since the terminal blocks were labeled well enough. I managed to get the CPU, GML, and the logic supplies hooked up. Unfortunately I have not had the same luck with the main supplies. I have a stranded 6AWG jumper wire that I know must connect the +22 and -22 supplies together and a thinner 3 wire that says 22V (probably a sensor) but I have no clear identifier as to WHERE they go. The client insisted I just try different combos until I got it right but I refused.

Anyways, I left defeated by 80's technology. I'm ready to refer this out to someone else but this client is really in a rush to get the board connected. Does any one have any sort of idea on how these supplies should connect together? The client has no manual and I'm at a loss on where these lines go.

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Dusk Bennett
Artist Development/Production
Audio Engineering
Los Angeles CA
www.duskbennett.com

ssltech

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Re: I need help
« Reply #1 on: January 18, 2011, 01:08:18 PM »

I'd pop in a prayer to the specialists...

http://81series.com/

And see if you can get the pinouts and connection info.

-Keith
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MDM (maxdimario) wrote on Fri, 16 November 2007 21:36

I have the feeling that I have more experience in my little finger than you do in your whole body about audio electronics..

zmix

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Re: I need help
« Reply #2 on: January 18, 2011, 01:30:31 PM »

ssltech wrote on Tue, 18 January 2011 13:08

I'd pop in a prayer to the specialists...

http://81series.com/

And see if you can get the pinouts and connection info.

-Keith


WOW! What an incredible resource!! Thanks for sharing, Keith!

radardoug

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Re: I need help
« Reply #3 on: January 18, 2011, 02:10:08 PM »

I think you also need to explain to your client that you need the correct  documentation to service and install his console. If you made a mistake wiring the supplies up, his investment in this console could be drastically destroyed!
Or teach him the lesson the hard way?? Grin.
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QUEEF BAG

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Re: I need help
« Reply #4 on: January 19, 2011, 01:02:59 AM »

Those things whig me out, it seems so wrong. As i sorta remember...(which means 81.com is best idea), both big supplies are +22V. Three lines to console.

First power supply is easy, the hot side to +22 and 0v to the common. This is the part that makes me queasy: the second supply the hot goes to common and 0V goes to -22 going to the console. That seems so stupid, but it's the difference in potential that we are hooking up.

Haven't installed one in a while so ya do wanna talk to someone intimate with those. The manual is of some help, but a tech on the phone is what ya want. If yer in L.A. you know Dave Clark? Most say he's the Neve guy of choice there
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Dusk Bennett

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Re: I need help
« Reply #5 on: January 19, 2011, 02:41:17 AM »

QUEEF BAG wrote on Tue, 18 January 2011 22:02

Those things whig me out, it seems so wrong. As i sorta remember...(which means 81.com is best idea), both big supplies are +22V. Three lines to console.

First power supply is easy, the hot side to +22 and 0v to the common. This is the part that makes me queasy: the second supply the hot goes to common and 0V goes to -22 going to the console. That seems so stupid, but it's the difference in potential that we are hooking up.

Haven't installed one in a while so ya do wanna talk to someone intimate with those. The manual is of some help, but a tech on the phone is what ya want. If yer in L.A. you know Dave Clark? Most say he's the Neve guy of choice there


Good memory, you described what I remember seeing to a tee. Of course knowing which terminal on the lower -22V supply is the confusing part since it wasn't labeled. The +22V supply did have a tag that said "to 22V lower" so I was able to deduce that this was probably where the link left but mo idea where it goes from there.

I don't know Dave but it sounds like I'm going to need to talk to him soon. Anyone have an email?

I'm also going to go to that link and follow up on whatever is posted there...
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Dusk Bennett
Artist Development/Production
Audio Engineering
Los Angeles CA
www.duskbennett.com

John Klett

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Re: I need help
« Reply #6 on: January 19, 2011, 09:34:23 AM »

81 series desks use raw unregulated supplies and locally regulate in the racks and on each module.  The audio supplies are hooked up like two batteries in series so one supply is the positive supply.  It's negative "terminal" is taken to common (0volts).  The other supply is the negative supply so it's positive "terminal" is connected to the console common 0volts.

If there is only one "sense" line - I can't remember offhand - it's not a voltage sense line it's a power fail/sequence line.  If it's a screened pair then the red would go to positive "rail" (the positive terminal of the positive supply), shield would go to common 0volts and black would go to negative "rail" (negative terminal of the negative supply).  When one of these desks is set up correctly you turn on a master breaker then push a start button on the top supply in the rack and the supplies turn on in sequence ... there is a 10 way (as I recall) ribbon cable that daisy chains down the back of the power supply stack that handles detection or power supplies being on or off and this goes up to a board in the PSU that has the start button on the front.

You do not want to connect and power one of these consoles for the first time with the modules in it...  the way to do an 81 or 82 series frame is to have it empty with nothing hanging off the power supply distribution and the make your power supply connections.  This is done so, if you power up the supplies for the first time, and if there is a problem or they are mis-wired, you'll limit damage.  Once you power up the frame measure at various points in the frame to confirm the right voltages are getting where they need to go.

There are capacitors in the frame that will announce reversed polarity by blowing up and making bad smells but those are replaceable and probably should be replaced anyway by now.

You really should get a book if you don't have one.  That may cost you a few hundred bucks but it's super worth it.

ALL the power in those consoles are locally regulated - so every module has TO-220 regulators onboard for plus and minus 18 volts for audio and I think 15 volts for logic.  There is a big fat ribbon cable for each module that carries the raw power supplies up to the modules.  This comes from the router switcher racks so the racks have to be connected to power for modules to work.

VERY IMPORTANT - IF you get all that right and BEFORE you turn on the console you MUST make sure EVERY MODULE, EVERY FRAME MOUNTED CARD, AND EVERY RACK GETS a 0 VOLTS connection.  Each module has a single conductor wire hanging off the bottom and that has to connect to a wire coming up from a zero volts buss in the frame.  If that wire is not connected or of the crimps i=on the little "bullet" connectors have gotten loose then the regulators in the module will have no reference and they will pop like little firecrackers.  Make sure the screws taking these ground wires to the buss are tight.

One time I was doing a console fader automation system install into a Neve 8232 console in ... Memphis? ...  and Fred Hill was doing the console commissioning.  While the console was powered, a cable with a bunch of xlr's hanging off it was draped over the power supply distribution block (not on purpose - just moving wires around during commissioning) and something slipped and shorted one of the audio supplies.  The sound of popcorn and a cloud of smoke resulted and Fred had to replace a ton of regulators and IC's...  I was so glad that I was only there for the faders.

So... that was enough for me.  I commissioned a couple 8232's for Neve and I've moved and worked on 8108 and 8128 consoles and I always double and triple checked power supplies and frame connections and powered frames empty, connecting things in stages and always always making sure all the black ground wires and their crimp connectors were solidly connected

note that patch bays are active and have power and ground goin to them

also that phase meter connector is unmarked and not polarized so make sure that's right - I did blow one of those up

thankfully I have not had to work on 81 and 82 series console for maybe... oh... at least 15 years

I hope you have a lot of switches - the switches on those things would loose their little plastic switch latches and not stay down...

good luck

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Dusk Bennett

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Re: I need help
« Reply #7 on: January 20, 2011, 10:25:21 PM »

Thanks for your input John. When I got pulled into this gig I was pretty explicit that I DID NOT want to commission the board, mainly because I knew the clients budget would not justify the cost to do it right (plus I'd likely blow it up just like every other board I've touched). I was just there to oversee the move. HE was going to unload and reload everything.

Once I arrived onsite for the move it became, "Well, we didn't get it done, so just unload the supplies and modules..." Once the board arrived at the new room he asked me to load up the modules since they were taking up room on the floor. One thing turned into another and now essentially I've recomissioned his console...

Go figure.

Anyways, my real problem was trying to figure out which terminal on the lower supply connects to the upper since it appears there's no legend for it. I looked over 8108 schematics today and all it shows is that the supplies are linked but it doesn't say where. The 22V sensor lines were there originally too but of course I can't figure out where they go either.

Your post is really making rethink the whole thing. I mean when we reloaded the board (last summer) we thought we did it right but we were rushing, just to get the modules off the floor, and there certainly could be some error in there. What you're saying implies even if we do hook it up right I could smoke stuff just because....

Ay, yai, yai....
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Dusk Bennett
Artist Development/Production
Audio Engineering
Los Angeles CA
www.duskbennett.com

bruno putzeys

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Re: I need help
« Reply #8 on: January 21, 2011, 03:04:24 AM »

BTW get a variac. That way you can slowly ramp up the supplies while you check a few voltages and see if they're going in the right direction.
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radardoug

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Re: I need help
« Reply #9 on: January 21, 2011, 02:17:40 PM »

Does your client have some sort of hold over you?
Otherwise I can't understand why you are proceeding with something that could end really badly.
Your comment about the customer 'couldn't afford to do it right'
makes alarm bells ring with me. If he has a console like this, and can't afford to do it right, then walk away now before it turns nasty.
We all have the right to say no.
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