I just assembled the latest version(1.6) of the JC-2 clone, which I purchased from eBay seller Jim's Audio.
I checked everything carefully as I was assembling it.
When it came time to try it out, all I had was a Rat Shack 25.2V CT 2A transformer to test it with.
After connecting the transformer and plugging it in, the LED on the +Vcc side flickered briefly and remained unlit while the -Vcc LED remained lit.
The instructions state to adjust the 2K trimmers to obtain between 15 and 20 volts.
My problem is the trimmer adjusts the voltage on the -Vcc side, but when I turn the trimmer on the +Vcc side it does nothing. The voltage stays at 17.4 volts.
So I adjusted the -Vcc to 17.4 volts(LED went out) and made the other bias and dc offset adjustments.
Can someone familiar with this design please tell me what may be wrong?
I've looked at the schematic, but I don't understand the purpose of the (3) BD140 & (1) BD139 transistors unless they are part of some type of voltage regulator circuit.
Thank you...
I checked everything carefully as I was assembling it.
When it came time to try it out, all I had was a Rat Shack 25.2V CT 2A transformer to test it with.
After connecting the transformer and plugging it in, the LED on the +Vcc side flickered briefly and remained unlit while the -Vcc LED remained lit.
The instructions state to adjust the 2K trimmers to obtain between 15 and 20 volts.
My problem is the trimmer adjusts the voltage on the -Vcc side, but when I turn the trimmer on the +Vcc side it does nothing. The voltage stays at 17.4 volts.
So I adjusted the -Vcc to 17.4 volts(LED went out) and made the other bias and dc offset adjustments.
Can someone familiar with this design please tell me what may be wrong?
I've looked at the schematic, but I don't understand the purpose of the (3) BD140 & (1) BD139 transistors unless they are part of some type of voltage regulator circuit.
Thank you...