FADERS MOVING

[Carlo]

Hi john,
Interesting. Would love to know were to check.

[Jondav1120]

Hi Carlo,

Here you go....the terminals you want are the four pin molex plug, +12volt is the yellow wire, 0v is either of the black wires.
Monitor the voltage at this point and if the voltage varies in sync with the movement of the faders......

Regards

John

[Carlo]

Thanks John i will check as soon as im at the studio. So the voltage should remain the same i.e. 12v during example calibration of the faders right? Whats the red wire for pls? Is it the 5v?

[Jondav1120]

Hi Carlo,

Yes, it is 5v, although this is the supply that powers the motherboard, not the 5v supply that powers the console, and as such has no connection through the PCB. The 5v supply for the console is the bunch of orange and black wires at the opposite end of the board. The five pin connector should have the +&-16v, AGND and +48v. The square four pin plug with yellow and purple cores is the +12v and MGND out to the console.
And, yes the 12v supply should remain stable during a fader calibration. May be slightly more or less than 12v, but shouldn't vary....

Regards
John

[Carlo]

Thanks a lot John.

Will let you know what i found.

Regards.
Carlo

[Carlo]

Hi John

I had checked all the points you mentions and tested normal however, I've just noticed that my d8b remote pc has the two small wires coming from the astec ps to the liner psu disconnected (its a small socket found near the bunch of orange and black wires on the liners psu). These small wires are colored orange and black. When i reconnected these 2 wires to the linear PS, the d8b did not boot up and instead the surface leds started to flash on and off (throbbing leds). What do you think is the problem? The previous owner might had experienced something and disconnected the wire.

Could this be the culprit of the moving faders?
Thanks
Carlo

[Jondav1120]

Hi Carlo,
Apologies for the delay in replying. The pair of wires that you mention is (I believe) used to sense the actual voltage on the 5volt supply rail at the pcb on the back of the BFC (PCB 111 in the schematics). If you check these you will see the sense wires coming in on pins 4 and 7. The idea of these is to regulate the voltage at the pcb to 5volts, so due to voltage drop under load along the cable the voltage at the 5volt power supply would be raised to compensate. I have no idea what the 5v power supply would do if these wires are disconnected (obviously nothing too terrible, as your D8B is still working....), however I would guess that it would effectively become an unregulated power supply, supplying its maximum possible voltage, which being unregulated can therefore vary with environmental and external power supply conditions.
Having had another look at the drive circuitry on the fader boards, it would be possible for slight variations in the 5volt power supply voltage to cause the faders to move slightly.
With the two wires connected what voltage are you getting out of the 5volt power supply, I'd guess that the output is pulsing in time with the LEDs.

Regards

John