Line Inputs Malfunctioning

[bURN]

Hello all,
My old trusty d8b is showing some age after moving a few times and being in storage at one point for a few years (original owner from 2000). Recently in the past year, my first 12 Line Inputs went dead, and now all 24 just stopped working. If I crank the gain input all the way up, I can get a faint signal that is barely audible that sounds all distorted and horrible.
I went ahead and cracked open the mixer, inspected all the main boards that are accessible and took apart the ones stacked at the back of the mixer. There appears to be no visible problems with capacitors leaking or bulging, they all look as new. I've always babied this mixer. I went ahead and cleaned and reseated all the ribbon cables with CAig DeOxit and ProGold.
After I spent about 8 hours doing all of this meticulously and putting it back together, I hooked it up and it worked! All the line inputs were functioning great again. And then within an hour, it reverted back to the same problem again. It was just sitting there, turned on. I don't get it...... so frustrated!

Any ideas would be appreciated, thanks!

[arjepsen]

Hmm... Not sure at all.
Check bios settings - just for fun...

I'm also thinking:
If you got a difference by cleaning those contacts, you must have touched/moved somthing that is part of the problem...
For good measure, clean the BFC connector also - my d8b sometimes behaves a little erratically, and sometimes twitching that connector helped. I've since cleaned it, and it helped (at least so far).

Maybe go back in, and see if there are any more things that can be disassembled, and cleaned?
Can the jacks connectors be cleaned?

Another idea - go over the block diagram in the manual, and follow the signal path. Might be a way to try to pin down the problem.

Anything else that doesn't work as it should?

Good luck!
Anders

[bURN]

Thanks Anders,

Overall, my board has been pretty stable over the years, compared to others I've known. It does have a random thing on startup that it's done over the years. About every 50th time or more that it boots up, some of the channel meters are pegged and those channels emit this high pitched digital SMPTE kind of sound. And then a few random glitches once in a rare while, all of which is usually remedied by rebooting once or twice.

I didn't mess with the Big Friggin Connector, other than taking the board off and looking to make sure the caps looked visibly ok, which they did. I saw some of the posts about the power connectors and such on here, when I have some downtime next I will try messing around with that, maybe try bending the pins to make a more stable contact, as someone suggested.

If there are any more suggestions, keep 'em coming please. I love my d8b and don't want to lose it!

[arjepsen]

Well, try to do a sort of process of elimination.

Your line inputs stopped working - try to figure out how far the sound gets before it stops. Might help you pin down the location of the error.
One thought though - if these inputs stopped working all at the exact same time, it could indicate something wrong with the power supply to the D/A converters. (just shooting blanks here).
I'd try cleaning the BFC - maybe check the power supplies in the PSU unit.

[FrankH]

I just want to reiterate what has already been suggested here by restating something I've said before elsewhere.

95% of everything that goes wrong with a D8B can be directly traced back to the integrity of the connections within the BFD. Exercise it, strain relief it, continuity test it, clean it. Try it all.

[captainamerica]

yep...could not agree more with Frank. I can't tell how many times I have went down the wrong debugging path only to find myself back at the BFD intersection !

[bURN]

Cool, thanks for the input fellas. I will check those things out and see what I can find!