A bit stummped - faders and v-pots not working

[slh2171]

Hi all,

Apologise if this has been asked elsewhere, but having trawled through a fair bit of this forum i thought i'd ask for help.

My d8b a while back had - what i thought - was the rail cap error. however, i believe it was a 5v problem due to the little dial on the Aztec power supply not being set properly as now the popping and flashing LEDs has stopped and all powers on normally, no error messages etc.

That said, the faders and the v-pots no longer work, the fader don't move or jitter (which they did previously), and the v-pots are stationary on the console, but (v-pots only) change when moved on the software.
I have tried other fader banks in place of the others but the same result

All other buttons work as normal in both directions, software<>console

All the voltages appear to be ok going into the brain board, and there seems to be 0-5v changing on the faders when moved manually.

The LEDs on the brain board and DSP are as follows

Brain Board
--------------
Green, whilst booting
then
blinking green, and very fast (strobing) red


DSP
-----
Green, whilst booting
then
7 green flashes
then
Red on

also on the master VU meter the levels are showing about +5db both on the software and hardware, though no audio is plugged in.

Has anyone else come across this problem or had a resolution?

Hope that kind of makes sense. Thanks in advance!

[RJH_MUSIC]

Take a look at the new power supply build I recently updated. I had the same problems while doing the build. There are several possibilities. I would in this order.

1. 5v Aztec supply is still bad. The console needs 5.38v to work properly. Dispite adjusting supply is still most likely. Bad
2. Faders are 12v supply problem but could also be linear power supply board problem. Check cpu power supply 12v output.
3. The +/- 16v rectifiers on the linear power supply board are isolated to the chassis heat sync. The is thermal tape between the back of the rectifiers and the heat sync. If the piece of tape is worn through from heat it will cause a short and will render the faders motionless. I don't know the reason why, but this very same thing happened to me during my build because I forgot to isolate the rectifiers. Took me 2 weeks to figure out and solve.

Still think option 1 is most likely cause of trouble. If your lucky enough to find a working one on ebay for $150 or less, jump on it. Otherwise a new one will cost double that.

[RJH_MUSIC]

Behavior of let's you describe is correct and indicates that brain board and dsp board are okay. Also, check with a flashlight inbetween the cards installed in the card bay. There should also be a red blinking led on the clock card.

[slh2171]

Hi, thanks for the reply, I appreciate that. I checked over those points you referred to. So far it seems i can get 5.38v with the astec board disconnected but when its taking a load it instantly drops to a little bit over 0v so i'm guessing that boards had it. I must admit i don't fully understand how that works, there is a second adjustment pot to the side of the 5v one, does that have anything to do with it?

Many thanks.

[RJH_MUSIC]

Can you please explain that again. The Aztec 5v supply is not a board it is the power supply that stands on its side next to the Linear Power Supply Board, (LPS). Both are located in the CPU. It you disconnect the LPS, you will not get any voltages because all of the voltages supplied to the console are are connected via the BFC from the LPS in the CPU. You can try to disconnect the sense output from the Aztec power supply at the LPS. Look for the tiny black and orange wires coming from Aztec PS that are connected to the LPS using a 2 pin Molex connector. The connector is located right next to the 10 Pin Molex connector on the LPS that contains 5 orange and 5 black wires connected to it. Reboot and see what happens. If it works, then the Aztec power supply is bad. TO be honest, even if it does not work, I think your problem is the Aztec power supply. I had a similar problem with mine. The sense output went bad and until I disconnected the Molex that supplies the sense output to the LPS, the console wouldn't even come alive other that than the LCD screen.

[Pollucs]

I had the flashing LED's issue as well and narrowed it down to the ASTEC LPS152 5V PSU. Sometimes unplugging the sense molex connector made it start, but not always and things got gradually worse. From experience I suspected the capacitors in the low voltage section of the PSU went bad so I replaced them and that fixed the issue.
Replaced caps:
3900µF/10V
2200µF/10V
1200µF/10V
100µF/50V
Cost, less than 10€