bosoz almost complete

[mjounot]

I just fired up my bosoz for the first time and checked voltages.
I have 86 volts at Q101 102
59 v reg. output
30 v at q1-2 drains
4.2 v source pins one channel
4.5 v other channel
The FETs and power resistors (cadocks on heat sinks) get really hot. Too hot to touch for more than 5 secs. I measured temps:
Q101-102=over 70 C
Q1-2=over 60 C
R1-2=over 50 C
R3-4=over 60 C
Are source pin voltages ok and what is safe temperature limit for mosfets

THanks
Mike

 

[till]

I run one of my Zen amps for month now, some hours every day. The heatsinks are at 75 - 80 °C at the moment. No problem.....

 

[eLarson]

The FETs and power resistors (cadocks on heat sinks) get really hot. Too hot to touch for more than 5 secs. I measured temps:
Q101-102=over 70 C
Q1-2=over 60 C
R1-2=over 50 C
R3-4=over 60 C
Are source pin voltages ok and what is safe temperature limit for mosfets

Thanks
Mike

You can touch 70 deg C for 5 seconds or more? You must have some terrific callouses! 🙂

Generally if you can touch the heat sink it is
considered 'okay' in terms of temperature.
However I've never heard of that temp being over
60 deg. C, though. Your transistors may not last as
long as they otherwise might at a cooler temp, but
it should be okay.

For what it's worth, I ran a Bride of Zen nonstop
for several years with no heatsink at all on my
IRF510s. There has never been a lick of trouble
with it.

(I'm hardwiring a BOSOZ-variant myself, actually,
otherwise I'd still be listening to it.)

Erik