Another Parasound HCA3500 Upgrade '25

[laup]

My 0.47 caps have arrived however as I see i have rubycon so I think I will leave on the board as it tests fine

I have also got myself a variable and made a light box for testing🙂

 

[laup]

Before I even try powering it on I think I'm going to address the issues that I have around the zener diode region

The problematic right side is alot worse in terms of scorching

But I had noticed the left channel has heat stress also, just now

So

With a bit of AI I found what probably needs to be done

If someone wouldn't mind giving a human eye over this as I have removed dynamic bias so the board will be subjected to alot more heat stress over time

@bigskyaudio what are your thoughts?

 

[laup]

r4 and r5 are measuring around 7.5 to 10 0hms on both boards when schematics say 15?

way out of tolerance, but consistent between driver boards, was this on purpose at factory?

Im lead to believe this could be the cause...