Premier 140 - Advice

[aldinohiend]

Advice. A few days ago on my Premier 140 will not light the LED to calibrate the bias of the V6. Yesterday, came my technician friend who has reversed, on the first, operational V6 with that of V4. Nothing. Subsequently reversed the zener V6 with that of V4. Still nothing. Were checked trimmer, resistance and welding without joining anything. The LED is not dead. Any advice? Thank you.

[Joe Appierto]

Have you tried a different tube in the V6 position? Sorry, I know this is an obvious question but sometimes it's best to start with the obvious.

[ronenash]

Obviously first check the tube.

Another idea is, try to bias the amp after it has been on from cold for 15-20 minutes. CJ amps are best biased after they have been working for 15-20 minutes. If the amp has been on for a long time (more than an hour) in certain cases some of the internal bias monitoring parts get hot and drift in value. I have seen this happen a couple of times so you might check that.

In any case I would not start switching parts in the amplifier. A more sensible way to check this would be to test the operating voltages of the different tubes. You can start by actually testing the voltage across the cathode resistor of the output tube. This voltage divided by the resistor value will give you the bias current.

You can PM me for more information as this is not a DIY forum.

[aldinohiend]

Thank you

[Myles B. Astor]

Originally Posted by aldinohiend

Advice. A few days ago on my Premier 140 will not light the LED to calibrate the bias of the V6. Yesterday, came my technician friend who has reversed, on the first, operational V6 with that of V4. Nothing. Subsequently reversed the zener V6 with that of V4. Still nothing. Were checked trimmer, resistance and welding without joining anything. The LED is not dead. Any advice? Thank you.

A friend had that happen in his Premier 8s. It turned out it was something in the biasing circuit itself and cj had to "rebuild" it.