I have a synthesizer (Yamaha CS-50) and the power supply is broken. I don't know why but it always blows the fuse. I tried everything, changing components, testing the transformer, etc. The fault is in the +15/-15V circuit, it doesn't give me the correct voltages, but the others are perfect.
I decided to build a new modern power supply, this one adapted to +15/-15V
My question is about the Sense circuit of the original power supply. Can I add a sense circuit to the new power supply, will something like this work? Do I need a resistor in between?
Sorry if the question is a stupid question, I am a rookie.
I have a progress, I did find the fault on the original power supply, was a rectifier diode, leakage diode, I did replace and now don't blow the fuse. Now the problem is that I receive a high voltage in the outputs on the +15/-15 circuit I receive the following:
+15V output= +27V +15V S output= 0V -15V output= -27V -15V S output= +27V
If you see in the original p.s, in the union of zd1 and 820 resistor I have +15V, and in the union of zd2 and the other resistor I have -15V, so the problem is onwards I suppose.
I did replace the 4558 and all electrolitic capacitors.
the other outputs 6.8V and 8.5V are perfect, what do you think where is the possible failure?
I don't understand why I have this values, perhaps the zener diodes or transistors associated?
Of course the connector of the synth is not connected, I not want to destroy the boards until the values are correct.
Thanks in advance.