Crest Century VX refurb w/ pics (advice needed)

[Funk-O-Meter]

I'm a live audio guy primarily and I'd been watching all these expensive beautiful old large format live desks go for nothing on Ebay cause nobody wants to deal with the size and weight of them anymore. I knew one day I'd have to bid on one and take a drive to get it and when I found this 64 frame Crest Century VX down in New Orleans and won it for $900 I knew it was time. I'd always liked these desks and I love to visit New Orleans anyway so me and my girl rented a van and hit the road for some R&R.

Here she is before I started. This particular desk had been FOH at the House of Blues in Chicago after it's birth in 97' or so so it's got a little mojo. Sorry about the imageshack links. Maybe I'll embed them when I get a second.

http://imageshack.us/photo/my-images/52/photojul0230515amhdr.jpg/

Testing all the LED's is fun:

http://imageshack.us/photo/my-images/814/photojul0232520am.jpg/

It begins. All found problems are noted on bits of white tape on the cards:

http://imageshack.us/photo/my-images/717/photojul0342323am.jpg/

First few channel cards I pulled:

http://imageshack.us/photo/my-images/856/photojul0275252pmhdr.jpg/

Mostly unloaded to clean and re-configure. Stacks of cards everywhere:

http://imageshack.us/photo/my-images/543/photojul0731509am.jpg/

As it is up to this point. Notice most of the little bits of white gaffe tape on channels with notes about problem are gone? A very nice thing to see.

http://imageshack.us/photo/my-images/683/photojul2345350pm.jpg/


So far I've un-loaded the desk and cleaned the frame and many channel cards, faders and knobs. I've replaced 16 bad LR bus switches that wouldn't latch anymore and several lost chips. I've found a few bad solder joints and broken traces and cleaned and fixed a dozen or so faders. Lots of de-ox'ing, blowing out and lubing of switches. I reloaded the desk to have the normal config of cards, put any problem cards at the end and fixed a couple funky sub groups that where coming and going. Ive got a couple matrix out amps circuits that are screwed, and a couple of EQ switches that pop. These should be pretty straight forward fixes (he says optimistically.)  As well I've found sources for replacements for missing knob and fader caps and sourced another PSU for redundancy.

What I need advice on is this: I've got a couple of audio sub-groups that have a borked pan circuit. The image is off center when the pot is in it's center dent and you have to pan to one side to get the image centered. On one it's pretty minor and on one it's pretty drastic. Any advice on this problem would be appreciated! Signalflow posted the schemo's he had over in the library section and I could post the relevant page in this post as well.

This project has been long but fun and I can't wait to get this guy done and start mixing and moding it It's going into the live venue I work at.

Hope you enjoy.   

 

[signalflow]

maybe test the signal around the pan circuit. at some point one side of it should drop in level.  Could be U8 or U9.  But it may just be a bad deck on that pot.  Crests tech dept should have spares.

-Casey

 

[Funk-O-Meter]

I was thinking since the LCR pan function is working fin that would rule out the pot and deck no? I could measure it but I'd have to pull the pot I suspect.

 

[signalflow]

I was thinking since the LCR pan function is working fin that would rule out the pot and deck no? I could measure it but I'd have to pull the pot I suspect.

Well it cant be working fine if the image is smeared    from the schematic they look like 4 deck pots, maybe pull one from a working sub group to test in the bad sub group.  I just think starting with the most direct suspect could prove to be helpful.

-casey

 

[Funk-O-Meter]

Your right I just saw that they are 4 deck pots. maybe I should swap it out and see. I've pulled the LR buss switch that I replaced earlier on that group to see if I hadn't damaged a trace under the switch on these double sided PCB's and not noticed. In doing so I ripped up a couple of traces even though I was taking my damn sweet time and now I've gotta fix that. So I've got that going for me.   

 

[Funk-O-Meter]

Got my sub group problems worked out. I had indeed toasted a trace or two under the switch when I swapped them out the first time. I really should invest in a Hokku 808 or some similar de-soldiering unit. These double sided PCB's are pretty easy to screw up when your de-soldering 18 legs. 

So now all the major problems have all been resolved and all that's left is the little somewhat ancillary issues like some mis-behaving LED's, a couple matrix output amps and repaint or replace the sides and wrist rest.

I was even toying with the Idea of repainting the bits of the frame I'm repainting in a different color or maybe fabricating some rubbed wood sides or something swanky.

BTW, what can I use for a reference +4db signal if I don't have a scope or other equipment with a tone generator built in? Can I use some software on my iPhone or something that might be calibrated to the known hardware? 

 

[signalflow]

BTW, what can I use for a reference +4db signal if I don't have a scope or other equipment with a tone generator built in? Can I use some software on my iPhone or something that might be calibrated to the known hardware?

http://www.softpedia.com/get/Multimedia/Audio/Other-AUDIO-Tools/Wave-Tools.shtml

I've used something similar, but this looks pretty cool.

Congrats on getting the groups worked out.

-Casey

 

[Funk-O-Meter]

Would I set this software up to give me a reliable +4db sine wave using say my M-Audio interface? Just set everything at 0 and the software's tone gen at 100%?