Loud Bang, then Surface goes dark

[captainamerica]

As Crash said...check the "Dreaded Rail Cap Failure" ref docs !

http://www.sonido-7.com/d8b/maintenance.html#Post8

The Dreaded Rail Cap Failure

This problem occurs on older d8bs and is accompanied by the following symptoms:

A loud thump from every output. Thump Thump Thump (somewhere around 80 BPM)
Lights and meters flashing on and off in double time to the thump
The lights on the pan pots twirl around
No control over the console from the GUI
GUI shows no signs of trouble
Sometimes audio will pass and sometimes not
Sometimes a restart will help but then it comes back
Eventually nothing will stop it
Note: Some d8bs will have similar symptoms if there is an interruption to clock or if an incoming clock is present when the d8b is booted up or if any digital device connected to the digital cards is on when the d8b is booted up. For instance, some boards will act up every time a MOTU 2408 is connected to the DIO8 card when booting. In these cases the thump does not always occur (though sometimes it does), and the pan pot lights don't twirl around, but there will be flashing lights and meters, and the monitor may (but not always) show "DSP Error, Last State Unknown" or similar.

If you have these symptoms and are not an expert audio maintenance technician, you need the help of an authorized Mackie Service Center.

[Bruce Graham]

Hi All;

Thanks for you suggestion and guidance with this problem.

The console did not "exactly" behave as stated in the above that captinamerica kindly sent.

I had single bang (like when a console is turned off, with an amplifier turned on).
All went dark. No LED, No Pan pots, no VMU. completely dark.
I still had the GUI and what appeared to be control over the console, but, obviously not.
Upon rebooting, everything worked for about 3 or 4 minuets then the bang and total darkness.

I am going to replace the Cap's as it is an older model, but wondering it it is something else?

I'll keep you posted
Thanks again
Bruce

[arjepsen]

You mentioned trying the desk with a different cpu unit - did you get around to that?
I'd make absolutely sure that the rack unit was fine before trying to solder in the small smd caps inside the desk.

[Bruce Graham]

Hey Anders;

I haven't had a chance yet. Maybe this coming week.

I have 2 CPU's. One working with a mechanical HD, that other works but trying to get the CF to work as the Mechanical HD is toast.

I'll keep you posted.
Cheers
Bruce

[captainamerica]

hmmm, I still think you should check for cable (ribbon/connectors) oxidation and corrosion ...However, the 3-4 minutes life could be heat expansion/short or P/S capacitor issues

[Carlo]

dear all
i had a loud thump from every output. Thump Thump Thump pulsating like the dreaded rail cap symptom but im sure its not the d8b since i swapped the mixers (since i have 2) and the problem happened again with my second d8b. Is it possible that the capacitors in the LINE PSU board within the PSU need replacement? Can you please help me out what capacitors i have to change? There are two boards that have caps however the line PSU board has 2 large ones. Can you please help?

[Phil.c]

I have had the thumps and it was the ribbon connectors, I'm not saying that's what's wrong with yours but before you start adding new caps, do a re-seat first....it's easier!

[Carlo]

Hi Phil,

I swapped my d8b with another one and it happened again. I believe that this is not a d8b case.

Rgds

Carlo

[captainamerica]

yep....as Crash said, sounds like Dreaded Rail Cap Failure

[Phil.c]

Hopefuly you should see the burnt out cap, the problem is, sometimes other components are effected