[Doc Jr 8156]

Hello,

Finally, last night I finished my Cornet.  I did all the upgrades to C5 and C6 caps, Star ground of C13 and C14 with D1, D3 and the CC upgrade.  However all my excitement went away when upon hooking my Cornet for the first time, it hummed.  The hum increased as you increase the main preamp volume.  I tried isolating the RCA jacks but still same result.  My Cornet's layout I think is the problem.  My inputs and output jacks are on the transformer side of the chassis.  In this configuration, I had to run approx. 8 inches of signal wire from the input and output hole of the PCB (w/c are located in front of the PCB, opposite the transformer side).  I appreciate all inputs to solve this problem.  I heard what the Cornet can do sound-wise (when you listen to the music and ignore the hum) and I really liked it.  Please help.  Thank you.

[mgalusha]

Doc,

A couple of questions.

1) Did you use shielded cable from the pcb to the jacks?
2) How near are the cables to the AC wires? Distance is your friend.
3) Did you twist all the AC wiring? This will help reduce the radiated field from the wiring.
4) Does it hum with nothing connected to the inputs? If so, see the above, if not, does the TT ground wire have any effect on the hum?

Mike G.

[Doc Jr 8156]

Mike,

I can't realy express how much I appreciate your help.  After trying some of your suggestions and some of GRD (who, I too am indebt, from precious explanations and patience)  I finally solved the hum.  My RCA jacks are on the same side where I had my transformer and IEC for the power cord.  The distance from signal wires (w/c are not shielded) to the wiring from the transformer is about 3 inches.  The turntable wire has no effect on the hum I found in my cornet.  When I grounded the input jacks to the chassis and just used 1 signal wire/jack per jack the hum went away.  I'm really happy right now.  I'l burn the Cornet tonight.  Thanks again.