Overload Light Coming on 4000 G channel

[perfectsnd]

I have a 4000G that the overload light comes when powered up.  I check all the individual cards in other working channels and all the card (group buss, VCA, Amp, EQ, Logic, and Dynamics) all work properly. If I put the module in with just the VCA card, the overload comes on immediately.

I'm not sure where to start looking on this.  Could anybody point me in a proper direction?

-Joe

[sintech]

013 CARD (VCA Card)

 IC T6 (quad op amp) does the overload indicator. No other IC's are involved, so almost 100% guarantee that's your problem :-))

[perfectsnd]

I solved the overload problem. One of the main 2A fuses had blown which was strange because the module powered up fine.

Now my problem is that the the channel shows the VCA at full, but no signal goes to the L/R outputs from the large fader. I have no VCA control with the fader at all.  I tried another VCA card in the channel and I still have the same problem. 

-Joe

[Matt Sartori]

I solved the overload problem. One of the main 2A fuses had blown which was strange because the module powered up fine.

Now my problem is that the the channel shows the VCA at full, but no signal goes to the L/R outputs from the large fader. I have no VCA control with the fader at all.  I tried another VCA card in the channel and I still have the same problem. 

-Joe

that's a bit odd. firing up as seeing LEDs turning on or firing up as in actually passing audio??

Matt Sartori

[perfectsnd]

The channels works and will pass audio through the small faders to out the busses and L/R busses.  No audio signal will be passed to the L/R mix on the Large Fader (through the VCA in mix mode) and VCA to meters shows the channel full open. The large fader has no control over the VCA level.

[seedubs]

I have to pull my fader pack out of the desk to reset the vca often. If it is stuck wide open its most likely the active circuit needing to be reset. You probably already tried this...

[perfectsnd]

I put the VCA fader out. This did not resolve the problem.  The minute I plugged it back in, it went to full on VCA open, but no sound out the L/R and no control of the VCA via the Large fader.

[seedubs]

try switching the faulty fader pack with one you know works to see if it is the fader or the channel ...

[perfectsnd]

The fader pack is fine. If I put a known working channel in that slot everything works fine. It is definitely an issue with the actual channel strip.

[StarF666]

You might want to check the 5V on the fader. I once had a faulty VCA board that couldn't deliver the 5V used for the fader to generate the VCA control voltage. Reason was a faulty regulator. It's pin 35 on the VCA card (82E13) but might be easier to check on the fader.

[perfectsnd]

Fader and pack are fine. Like I said I put a know working channel in the slot and everything is fine. Full fader control.

[StarF666]

The 5V control voltage is generated on the 13 vca board. Your fader might be fine but if it doesn't get the control voltage, it cannot control the VCA. Might of course be anything else on the vca board but I remember a similar problem and it was a faulty 5V regulator on the 13 card.

[perfectsnd]

I put in a known working VCA card (13) and I still have the same problem. Like I said, i can fully known working channel in that slot and everything works fine with the fader and the vca on that.  I am stumped where to look.

[perfectsnd]

I narrowed it down to the RC4 signal. At pin 23 on VCA card I am getting on 12.8.  When i push the cut switch no change in state occurs. I am also getting the 12.8 on the logic board pin 6. I replaced the cut switch, but I still have the same issue.  This is causing the channel to think it is in permanent cut mode.

[perfectsnd]

I verified the RC4 switch is working properly.  I able to get the proper 0 and +18V on a trace right before the signal enters the VCA card on pin 23.  I then check pin 23 on the VCA card and I get +12.8 and hitting the cut button doesn't change the value.