D8B Console Blinks on reboot only when warmed up/hot

[Malfeitor]

I'm a bit at wits end here. My HDR and D8B works perfectly for an hour or two if its stone cold. I've had this desk and recorder for 6 years and have done the following to get it running and keep running over that time span:
Replaced the MB in the HDR
Recapped the MB in the console "power supply"
Replaced the video card in both
Converted both to CF cards
Replaced both PC power supplies
Both are running the last/latest OS

About 6 months ago, the console would start glitching out with all kinds of wierdness and force me to shut it down. Over the holiday, I did the following to try and address this:
Recapped the linear PS completely
Recapped the power distro board in the desk
Recapped the Astec LPS152 +5v PSU
Replaced the .1uf 25v rail caps on the brain board with .1 uf 50v ceramics.
Replaced/upgraded thermal interface material on the VRs for the Astec PSU

Boots and starts up fine with ZERO anomalous noise - sounds perfect for about 2 hours then weirds out. To me it seemed to be aged electro capacitors which some did read crappy ESR but none exploded.

Any thoughts on what it might else be? Attached a pic of it running fine on boot. The HDR is hammer proof perfect.

CR Mackie Console

20241226_230540.jpg (Array MiB) Viewed 1000 times

[Y-my-R]

I've been hesitant to respond to this, since you clearly have a much better clue about electronics than I do (I would not dare doing what you described that you did, by myself, and personally would have to bring it to a professional for a re-cap).

That's why I figured you probably already did the full "ribbon cable clean/reset" that is typically always the first answer, for any sort of lockup problems with the D8B (and to some degree also the HDR)?

My guess is, that this is a "thermal expansion" problem, that impacts a contact (or multiple) that already don't make very good contact, but lose contact completely when the device and it's components warm up.

Whatever tiny surface area that made contact, ever so slightly "changes" because of the material warming up and expanding... and somehow through that, loses contact, where it SHOULD make contact.

So, unless you've already done this, IMO a full ribbon cable reset should be done. Likely including Phil's signature tip of making sure to pry apart the connectors on the ribbon cables a little bit (using your thumbnail or a guitar pick or something), so you can see the spikes that pierce through the cables inside... and then put a drop of good quality electronics cleaner in there (e.g. DeOxit) or a drop of high percentage Isopropyl-Alcohol, to clean the contacts INSIDE the connectors a bit.

The ribbon cables in the D8B are the #1 cause of odd behavior in the D8B... and this CAN manifest in combination with thermal changes (warm up).

Of course it could also still be defective components or bad solder spots. I'd take a very close look at all the yellow capacitors on your Clock Card in your D8B. If it's an Apogee Clock card, the solder spots for the caps on those seem to frequently go bad and need to be re-flowed.

I even had an Apogee clock card where such a cap fell of completely, and another two where the contact on one of the caps was completely interrupted. They still worked normally for the most part, when running on internal clock... but at least with one of the clock cards, it worked fine on external clock when cold, and then started acting up and giving pops and clicks when getting warm. So, in that case it was a combination of solder issues and the affected caps not doing their job because of bad contact...

So... check caps on clock card, and if those are alright, I'd do the full ribbon cable clean, including cleaning inside the connectors.
Also don't forget the connectors inside the power supply. Those also often have bad or intermittend contact if they've never been cleaned in the desks 20+ lifespan.

Best of luck!