[solved]DM-4800 control surface stopped working

[erlkönig]

Hi,
i have the following problem with my DM4800: from one day to another, without having changed anything or having moved the console, all softknobs, incl. pods under the display and transport buttons stopped working. The console seems to work: fadermoves are working on the current mix, meterbridge is working. I can use the transport (MTC) together with my DAW via mixercompanion. The display works, but all lights in the knobs are permanently off. It's not possible to mute or solo a channel, change subgroups, etc. The knobs don't light up, when the device is turned on.
There are three ADAT cards inside. No errormessage is displayed. Firmware is latest version.

I remember there was something like a self-test for that console, but i forgot, how...

To my first impression, it looks like maybe the connection from the surface to the rest of the device is missing.

Does anyone have an idea about a solution?

Thanks in advance

 

[mixerizer]

hey there - so sorry this happened! sounds like something physical went wrong, perhaps a part can be replaced or needs to be reconnected inside.

the service manuals and diagnostic instruction for the DM-4800 can be found in the documentation and manuals section, at this link - https://elektrotanya.com/tascam_dm-4800_digital_mixing_console_sm.zip/download.html

good luck and i hope your mixer is fixed soon!

 

[erlkönig]

Thank you for the link to the zip. The scheme perfectly matched to the behaviour, based on a missing physical connection from the panel to the pcb.
I put the jacks in and out a few times, nothing happened. Then i thought it would be a good idea to measure the battery (CR2032), as the console was opened. It was at 2.7V. I quickly bought a new one, set it in (a shot in the dark...), turned the console on - and everything worked again.
The board was without that battery for about a quarter of an hour. Maybe the failure was a software problem and the missing battery did reset a part of the memory? I can't really believe that low voltage can cause such a specific failure (i never had a warning about low voltage).
But in the end: it works again and as i had to buy two batteries, i precautionarily will change the battery in my DM24 (hopefully it's the same type of battery).

 

[mixerizer]

Oh far out! thats great to hear, nice job! i did a few recent battery swaps (2032 also i think) in x-48s, but not in any DM-4800’s. Sounds like it helped clear some bad info!

 

[erlkönig]

...same problem again...
Can someone remove "[solved]" from the Thread heading? Thanks!

 

[mixerizer]

did u also donthe whole sram init thing w the battery swap? u might need a fresh reset (although u may already have thought of that). good luck as you set about solving it!

 

[erlkönig]

...it runs again...
This time, i detached the voltage-feed from pcb to the panel, reattached it and smushed the cables into the socket again. I wobbled the cables, but there was no hint for a defective contact or a cable break.
I guess, when changing the battery, i touched the cable (their very close to each other) and something happened...
For diagnostical reasons, i removed the battery an switched the console on - everything worked, so the battery doesn't seem to have anything to do with that behaviour.
Does anyone know the pin-assignment of that voltage-feed cable from PC to the panel? If it's happening again, it would be interesting to measure. Unfortunately, when all was open and working, i forgot to do that.