Zen v4 problem

[arlekin]

Hello!

I would be grateful if someone could give me few advices.

I tried to power up zen v4 last night fot the first time. The problem is that the voltages don't check.

I used IRFP044N for the Q1 & Q2 and IRFP240 for Q5. The unregulated supply is 57V and not 50V so friend suggested Ii should use IRFP240 because the breakdown voltage of IRFP044N is 55V.

After the regulation I have 40.5V and not 42V !?

Anyway, I adjusted of Q1 to 23V (or 22.25V in other turn) but I coudn't get the 4V across gate-source of Q1, Q2 & Q4. The voltages was 3.5V, 3.5V & 3V, respectively. The voltage on R1 was almost 0.66V. It was 0.65V on the second channel and somewhat smaller on the first channel.

I have checked the components and everything seems to be ok. The board is handmade according to specs

What do you think the problem is? Is it IRFP044N? Because someone said that if using IRFP044N instead IRFP044 one needs to readjust the values in the rest of the circle.

Btw. I accidentaly burned the Q1 on the first channel while sticking those probes. Will replace it, but need to correct the second channel first. Man, did those R1 & R0 shine. lol

Here is a pic:



Thank you!

[Netlist]

I experienced the same tolerances in voltages.
I turned out I nevertheless had a perfectly good working amp.
Nice boards you have there.

/Hugo

[Blues]

I don't see any problem...the values on the schematic are there for reference only...your readings are close enough. The PS value of 57V must be unloaded. Try measuring that value with the Zv4 connected. Also, check the voltage across the string of zeners on the regulator and make sure that's 9.1V x5.

On Q5 it's only about 8-10V across its D-S so no problem with 044s.

Connect, sit back and enjoy!

[arlekin]

So it is just the reference voltage? Ok, I feel relived.

Yes, it is 57V unloaded, with Zen it is about 51V. Anyway, I will check the zeners.

Thanks!

[arlekin]

One channel is working!