Studer A80 RC MK2 issue

[Chrome Heart]

We have this machine and it has and interesting problem. While in record mode, it will make a bump/static noise and the LED's on the Oscillator card will flicker at the same time. The VUs also jump at the same time. The noise also prints to tape. Any ides? Thanks

 

[fazer]

Might be in the master bias osc.  I don't recall how all that is done but the bias on the channel is fed from a master osc running at 240k.  that osc. is down below the transport in the card cage I believe.   

The first thing to check is the power supply for correct voltages.    An oscilloscope is needed to look at those voltages and not just confirm values on a meter.  Make sure there is no noise on the voltage with the scope.

Start with power first then break out to the circuit cards. 

 

[Chrome Heart]

Thanks Fazer. I was already in the process of checking the PS

 

[Chrome Heart]

Power supply voltages are good. I suspect the bias/erase card 1.081.985