Q27 emitter -13.13
Q28 emitter +14V
The collectors of these should be near zero but they measure 14v
Allready replaced Q28 and Q15 without any changes
You have two voltages written beside TP3 and TP4. Which is the actual one in each case?
Andrew
If TP4 is indeed -12.5V and the emitter of Q27 is -13.13V you are close to Q27 not being forward biased and there will be no Ic through Q27.
Can you measure the voltage at the node between R27 and R6 and also the node between R34 and R29?
They are the 220 ohm resistors that drop the main +/- 24V rail voltage to the "target" +/- 12V at TP3 and TP4. These nodes are also connected to C14 and C15, respectively.
Have you double checked that the six 3v9 zeners are all the correct type and are installed with the correct polarity? To double check you can measure the voltage at the zener side of R10 and R31.
Thanks ungie, I am busy with something quite revolutionary so i can not concentrate on two things at ones. My system sound so nice at the moment that i decided to do a session.
Yes, this seems fine. So something else is causing the current imbalance between the two polarities of the circuit. Because those voltages after the first 220 ohm dropping resistors are very close in magnitude (18.8V, -18.6V), if the current draw was identical in both polarities the values at TP3 and TP4 would be nearly identical. It's actually the current drawn by the positive branch that is slightly low from what it "should" be.
There are a couple of ideas now:
Measure the voltage at the opposite side of each component connected to TP3 and TP4 (emitters of Q4 and Q5 and the non-TP sides of R14, R37, R36, R38, R39, R30).
OR, if you're willing you can lift one side of R34 and insert a ~20 ohm resistor in series with it. This will drop the voltage at TP4 another 0.5V and make sure that Q27 is conducting. If we now have a low DC offset at the input to RIAA we can work through what is the cause of the current imbalance.
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