perhaps the 317 is the defendant: on its central out pin I don't detect 12v: I detected with the DMM connected to the GND of the P.Supply and the positive on the central out pin = ZERO.
On the input pin of the 317 I read 9V: this puzzles me.
In AC I detect 16 V before the rectifier bridge
On the input pin of the 317 I read 9V: this puzzles me.
In AC I detect 16 V before the rectifier bridge
LM 317 pinout is - numbers to you, pins down : most left Adjust, mid out, most right input
all ref to GND:
on input you must see close to your Aux AC*1.41; if you have 15Vac there, DC must be close to -20Vdc
of course, worth repeating, that Aux (15Vac) must be independent/floating of main audio PSU secondary
so, confirm that you have proper Aux AC voltage, then if anything is fishy with LM317 voltages, replace it
all ref to GND:
on input you must see close to your Aux AC*1.41; if you have 15Vac there, DC must be close to -20Vdc
of course, worth repeating, that Aux (15Vac) must be independent/floating of main audio PSU secondary
so, confirm that you have proper Aux AC voltage, then if anything is fishy with LM317 voltages, replace it
the preliminary checks carried out before assembling the components do not always give us back the truth. I discovered the component responsible for the problem after examining it several times and found it suitable, I set it aside. It was the R8 which, checked again today with another tester, did not return any value: it was the faulty one and also interrupted the circuit in its position. I happily replaced it on the fly and of course was able to bias the buffer to 20mA. Finally the first step is done. Obviously if I had sensed that resistance was about to die I would not have tried frantically to shoot into the pile...and despite the shots no one fell...I was swollen with rage that was the engine to control everything again. I hope I don't have any more problems. Everything went smoothly in the previous construction of the Bush.
I thank ZenMod who generously helped me: I'm leaving again also thanks to your support
I thank ZenMod who generously helped me: I'm leaving again also thanks to your support
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biased the power section. Obtaining it was not easy: I had to change the values of two Resistors.
The first on the MU board R3 increased from 100 to 150 R. The other on the SIT board, R11 increased from 1k5 to 3k3.
So I was able to get the design values: 460mV for Iq and the potential of 37V on the drain of the SIT (2SK180). Good progress. Tomorrow I fight with the other channel
The first on the MU board R3 increased from 100 to 150 R. The other on the SIT board, R11 increased from 1k5 to 3k3.
So I was able to get the design values: 460mV for Iq and the potential of 37V on the drain of the SIT (2SK180). Good progress. Tomorrow I fight with the other channel
Attachments
bias OK for the other channel as well.
In this case I had to increase R11 to 2k7 on the MU board and increase R3 on the SIT board to 220R.
Very good.
Even with an initial block that confused me a bit (the cursed R8 ) everything works according to the directive of Maestro ZM to whom I pay my respects
In this case I had to increase R11 to 2k7 on the MU board and increase R3 on the SIT board to 220R.
Very good.
Even with an initial block that confused me a bit (the cursed R8 ) everything works according to the directive of Maestro ZM to whom I pay my respects
Great Zen Mod, the new Bush is playing. Wonderful as always: the magic of this amp repeats itself. Forget the hitches of the initial tests, now the Music and what Music.
A lot of gratitude for the help you have always given to everyone, not only to me, but above all for having given us this incredible amp.
A lot of gratitude for the help you have always given to everyone, not only to me, but above all for having given us this incredible amp.
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