d8b Forum

So I bought my d8b over 6 months ago and it sat waiting for me to build the studio. Last night, with the sudio finished, I set it up and all appeared OK. An initial false start with a n ill-fitting (tight) power supply lead caused the board to cycle power but then all was remedied and it worked find for a number of hours. Being a newbie to the desk, I spent time after hours playing with effects and routings and noticed apparent signals on CH25/26 and CH31/32. These "signals" remained pretty constant (even with all inputs to the desk removed). Try as I might, I could not get rid of them.

Having set up various routings, I saved the project and shut the desk down. I then powered up (almost immediately) and was presented with a display of flashing LED's, posessed meter bridge and an audible "click" around 2Hz.

I shut down and tried again to find the same issue.

I went to bed with a sunken heart and tried again this morning. Initially, the desk fired up and appeared fine then a couple of minutes in it did the same.

Having read various posts, I'm concluding this is a rail capacitor issue. On the off-chance it isn't, tonight I pulled each FX and other expansion cards and reseated. On power up, again the board initially behaved as it should. CH 25/26, 31/32 were clean and silent and I rejoiced in what I thought was an easy fix. 10 minutes later the problem returned.

So, my questions are:

1. Does this indeed sound like a rail capacitor problem?
2. Did I cause it by the inadvertent power cycle with the initial poor power lead connection?
3. Does anyone have any good suggestions for electronic techs in the South West (I'm in Devizes, Wilts)

Appreciate your thoughts folks. I'm currently feeling disheartened having spent a good part of the last year personnaly building the studio and on its maiden voyage the desk died


Thanks in anticipation....

The fact that it works ok for a while and then goes crazy doesn't indicate a rail cap problem to me. Once a rail cap goes, it's gone and the problem would be immediate.

It seems heat related and possibly to do with the ribbon cables running from the power distribution board within the console to various modules. This is one of a few articles in the database that deals with such things.

Let us know how you go.

Peter

Thanks for the suggestion Peter - this is definitely the way to go first. When I bought the desk, I drove it home over 200 miles so there's a good chance things got a little unsettled. Fingers crossed it's as simple as that! Will let you know the verdict...

Another thing to check is your word clock sync settings. If you are running digital inputs ie adat/tdif/aes on the tape layers then you will need th apogee word clock installed...not word clock cables hooked up to each card.

So I got the desk to a local repair man who just so happened to work for centronic designing and building desks. Although I've only had the desk on briefly, all appears in order. It did however take some time for the fault to appear for him. Here's what he reported which may prove helpful for others presented with similar symptoms:

•fault replicated after 2.5 hours use
•cable inspection (power) in PC and Mixer: re terminated large cable into mixer
•power distribution board - capacitors ok
•EFX cards and all other modules taken out and inspected for capacitor failure. None obvious. Connectors / sockets cleaned, re-inserted
•brain PCB removed. ADC capacitors x6 replaced with new
•PC/PSU unit full of dust/debris. Cleaned out, fans cleaned - ok

Prevention Measures:
•Recommended ADC capacitors x3 replaced pls 3 others
•PSU Board distribution ok
•fader PCBs not removed but reports of these can be a source of concern with intermittent movement


All-in-all, this looks to be a thorough assessment and service so fingers crossed all will now behave!

As you mention, I would dismantle the console, and the ribbon cable cleanse them with isopropyl alcohol because it seems a problem contact

Hello all,

I think it's now fixed.....

After what appeared to be the fix (see post above), my problems returned again. Time for the problem to occur was random (immediately on power up, 10 mins into a session, 4 hours into a session....) and there was nothing I was doing that could be considered to trigger it (sometimes the desk would go mental just sat there with no user intervention).

I got the desk back to the same repair guy and he traced the fault to a problem on the power supply. The 5V DC output was not holding stable and therefore sent everything in digital world into meltdown.

I've summarised below the technician's report:

Reported Faults:
Pulsing / output audible "click" on headphones / LED's & pots flashing / Meter bridge flashing on & off

Repair Notes:
Soak test 3x 1 hour sessions, no fault replication
Power interruption - prompted fault. Repeatable
5V power rail pulsing on and off
5V power supply at fault
5V power supply also noisy at 350-500mV. Should be 50mV max
Replaced with 150W 5V 30A new power supply
Also replaced reservoir capacitor on mixer power board - 10,000uF 16V with higher rated ripple current

So far, it's working a dream. Early days, but I want to share with you in-case anybody else is suffering what might first appear to be a rail capacitor problem.

Cheers all!