This receiver had typical Power Supply Transistor / Resistor overheat situation. Everything still was functioning so I decided to renew PS board components per Mark's part list. While I was waiting on parts to arrive I cleaned all controls and switches along with cleaning of Bias and DC offset trimmers to prevent them from opening up on me during adjustment. This happened to me before and caused pretty bad situation on SX-929.
Now receiver is back together and I'm taking amp measurements. DC can be adjusted close to zero with very minimal fluctuation. Idle current is 20.5mv on one channel and 25mv on another with trimmers at min. I took pictures of trimpot positions before I moved them for cleaning. Original position of the trimmers was somewhere in the middle. That tells me that bias was way too high, I wish I had actually measured it before doing any work to it. I just didn't want to keep receiver ON with PS board looking so scary.
Idle current being so close to Mark's specified 20mv I suppose my situation is not really bad but probably has a tendency to get out of hand at some point. What would you guys recommend to do?
Now receiver is back together and I'm taking amp measurements. DC can be adjusted close to zero with very minimal fluctuation. Idle current is 20.5mv on one channel and 25mv on another with trimmers at min. I took pictures of trimpot positions before I moved them for cleaning. Original position of the trimmers was somewhere in the middle. That tells me that bias was way too high, I wish I had actually measured it before doing any work to it. I just didn't want to keep receiver ON with PS board looking so scary.
Idle current being so close to Mark's specified 20mv I suppose my situation is not really bad but probably has a tendency to get out of hand at some point. What would you guys recommend to do?