Still don't understand why the base of Q1 can be almost ground, and the emitter/output 14V.
Which transistor type did you use for Q1?
Jan
Which transistor type did you use for Q1?
Jan
I appreciate the help. Every time I think I have learned a little, something like this happens. 🙂
I had this thought as well Salas, but initially it was connected at the riaa board and yielded same results. All sense connections are closed and each board has a 500 ohm load across outputs.
The thing is, the base of the pass Q1 is at gnd and Vout is 14V. WTF??
Did you remove Q2, did the LED light up?
Edit: each board is fed from a separate isolated xformer winding through its own rectifier and cap? No connections whatever between the two raw supplies?
Jan
Did you remove Q2, did the LED light up?
Edit: each board is fed from a separate isolated xformer winding through its own rectifier and cap? No connections whatever between the two raw supplies?
Jan
With q2 removed, the LED lights up. The rectification arrangement can be seen in pic. Common ground is created after the cap in pre filter.
yup. No change otherwise. not by the circuit at the moment. FWIW, I tested diode junction of the pass bjt's and it was good.
Base of Q1 to ground is 6mV. Something has changed. There is no voltage across outputs of regulator
Finally something that makes sense. ;-)
Now put an R of say 10k from the raw input to the base of the pass Q and see what happens.
Does Vb go up towards 10V or so?
BTW can you double check that the pos pass Q is indeed a D44?
Jan
Now put an R of say 10k from the raw input to the base of the pass Q and see what happens.
Does Vb go up towards 10V or so?
BTW can you double check that the pos pass Q is indeed a D44?
Jan
That pass Q looks fully on with base at ground. So it is either broken or there's a soldering short.
Can you check and/or replace?
Jan
Can you check and/or replace?
Jan