Got this beast. Left channel failed, two mosfets blown. Driver mosfet source resistor blown but mosfet seems to be ok. However the circuit looks a bit odd to me.. power mosfets are capacitor coupled to the driver stage like tube anplifier. What do you think about this one? I made a quick schematic of the power and driver stage.
Attachments
Exactly like a tube amp, except there are no P-type tubes.
To my eye, you have mis-drawn the Gate on the P-devices. It is complementary cathode followers with individual bias. There are ways to do this, but this way is fine on paper.
I don't see MOSFET driver?
Driver is that single transistor (it is actually mosfet!). My very quick drawing has some mishaps but I hope you get some clue about this circuit anyway 😀
Sorry about that.
Anyway. There are bias trimmers for both halves. How about offset, carefully adjusting both bias trimmers? How about temperature compensation.. I just cannot figure out if it is stable enough.
Hi all
I am new to this group and hope you can help
I have the same amplifier on my bench with a similar issue. I have one of the dioded faulty but cannot figure out a replacement. On the diodeds it says CJ2PH. Does anybody recognise this value?
I am new to this group and hope you can help
I have the same amplifier on my bench with a similar issue. I have one of the dioded faulty but cannot figure out a replacement. On the diodeds it says CJ2PH. Does anybody recognise this value?
Does it say C12PH on the body of the diode by any chance? If this is the case, it is a C12PH == BZX55C12, 12V, 500mW, Zener Diode, manufactured by Philips Semiconductors (now NXP).
It looks like a J to me - CJ2PH. If you look at the circuit atthe bigining of this thread you can see the position of the diode. It looks like a clamp configuration to me. I suspect a schottky diode but not sure. It is a small glass diode.
See photo
See photo
Looking at the working channel I can see all diodes are identical so it is not, as suggested, a zener and diode in series