Hertz hp1d full rebuild

Lenin89

Member
2019-03-03 2:33 pm
Varna
Full rebuild.

I've already removed all the FETS in the PS section and the Output section.
All dead.
Output driver board for the class D is still in place as I have to fix the PS section first.

I've checked the gate drive in the PS just before the gate resistors (as this ones also have to be replaced).

I don't think this is normal. Two of the banks driving one of the transformers look shifted upwards. The other one looks normal. Pictures attached. So I think i will have to rebuild also the PS board - i think it is the buffer driver transistors.
 

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Okay, this is some generic KA7500 board design but i think it's pretty much almost the same as mine.

As i can't read the markings on the burnt transistors, logical thinking brings me to the conclusion that they were marked as BE RN = BCX55**, a 1Amp NPN transistor in SOT-89 ?
 

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2SB1260 and 2SD1898?

I've mistyped the DF with the DK...and got it all wrong.

The marking for the NPN's is NOT "DK" but "DF" - which indeed comes as 2SD1898 so no matter what's the marking on the PNP's, they are for sure 2SB1260...

As I stated before, they are unavailable in my region. So I will use BCX55-16 for 2SD1898 and BCX52-16 for 2SB1260.

Driver board has not become conductive but there are some burnt traces...is there anything better and more reliable than jumper wires ?
 
Power Supply section fixed. Pain in the a** to fix the PS buffer transistors traces but i managed it.

Driver board - DWM3640 - rebuild - done.

I've manage to try the amp with only one MOSFET irfp264n per bank. Runs fine. There is clean sinewave at the output. Just waiting now for whole new batch of irfp264n.
 
I'm buying mostly from Farnell.
So there are IRFP264 but without the N as a suffix which looking at the datasheet are not quite what the IRFP264N are. I'm happy I still haven't ordered them.
So the closest and available ones i could find are FDA59N25 or IRFP4332Pbf and i'm leaning towards FDA59N25 due to more similar parameters with the 264n's.
 
I'm buying mostly from Farnell.
So there are IRFP264 but without the N as a suffix which looking at the datasheet are not quite what the IRFP264N are. I'm happy I still haven't ordered them.
So the closest and available ones i could find are FDA59N25 or IRFP4332Pbf and i'm leaning towards FDA59N25 due to more similar parameters with the 264n's.
fda59n25 may seem ok, they are easier to drive, but they are a little too slow compared to the originals.
Many amps that use the same design, use FDA59N25 without problems, but the only sure thing you can do is try.