Hertz hp1d full rebuild

[Lenin89]

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.

 

[Lenin89]

Kaboom...

I have to look up somewhere for schematics to rebuild this. I was extremely careful while removing the SMD transistor but still....

 

[Lenin89]

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 ?

 

[ultra]

Can you take a photo of the underside of the board close to the speaker connector ?

 

[Lenin89]

Yes I can, no problem - but it's going to be tomorrow.

 

[Perry Babin]

2SB1260 and 2SD1898?

 

[Lenin89]

As much as I could see the markings these transistors are BE RN and DK RG which I believe are: BCX55-16 and BCX52-16 and these I can order from Farnell.

2SB1260 and 2SD1898 are impossible to find in my region.

 

[Perry Babin]

Look at the connections for the transistors. The PNP transistors will have their collectors directly connected to ground. Use whatever you can get but make sure you have the NPN and PNP in the correct locations.

 

[ultra]

Yes I can, no problem - but it's going to be tomorrow.

Will you take the photo ?

 

[Lenin89]

Yes of course, but i'm still driving home. I promise when I come back to my place I will.

 

[Lenin89]

Hope this will help.

 

[ultra]

Unfortunately i have an HDP1 amp in front of me, sorry, i was wrong

 

[Lenin89]

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 ?

 

[Perry Babin]

I've never had jumper wires fail but you have to use common sense. What part of using jumper wires would you believe that makes them unreliable?

 

[Lenin89]

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.

 

[Perry Babin]

Are you sure that the irfp264ns are legitimate originals? I thought they were obsolete.

 

[MarioRestucci]

Are you sure that the irfp264ns are legitimate originals? I thought they were obsolete.

i've recently repaired the same amp and replaced the 264N with FDH44N50 without problems and yes, IRFP264N are original part number.

 

[Lenin89]

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.

 

[MarioRestucci]

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.

 

[Leolabs]

Normally for this kind of 'burned' track pcb,i will just reverse engineer it if not that complex and fabricate a new pcb,since it's cheap to get a new pcb nowadays.
Downside is,u need to spend more time than usual.