Orion HCCA 2100 MUTED OUTPUT

[elchino10]

Hi everyone,
I have a orion hcca 2100 that I repaired..... partially. The mute mosfets are not getting turned on, I have the opamp output but the mute fets off..no output. does anybody have had this problem. Any help appreciated. When I remove them I have output.

Thank you,

Raf

 

[Perry Babin]

DCV on the gate terminal of the muting JFETs?

 

[elchino10]

gate terminal has just 10mV measuring from 12V gnd. and see no voltage getting to drain or source either. Can't find what feeds the drain voltage either. I hate working without schematics😱

 

[Perry Babin]

What's the resistance between the RCA shield ground and the primary ground with no RCAs plugged into the amplifier?

 

[elchino10]

120 Ohms to 12V ground and 0 0hms to secondary ground.

 

[Perry Babin]

See attached. Point Z drives the gates of the muting transistors. Find why they are not getting the negative voltage they need to pass audio.

This is a 225 but the circuits should be similar.

 

[elchino10]

Thanks Perry for all your help. optocoupler and all circuitry around was fried and that was the reason for muting the mosfets. Schematic helped a lot

 

[cheezemanrich]

Hi Perry, Do you have the rest of the pages of the 225 schematic you could post?

 

[Perry Babin]

See attached.