Jan-Erik Soderholm wrote:
>
> OK. Thanks Mike.
>
> So it would be OK to just short the diod (or to replace it with
> a blank wire) then ?


BAD idea! :o)

When I was about 21 I worked as a arcade machine
repairman (now *that's* a way to get lots of hot
teenage chicks but we won't go there) most of the
machines had multiple panels full of 5v logic chips,
used multiple 6800 or Z80 processors, and used
disgusting amounts of 5v supply.

Most of the 5v PSU's were adjusted to 5.5v or even
more, and one of the "faults" I was often repairing
was to check and adjust the 5v supply.

If the 5v dropped to (say) 5.3v you got a lot of
problems with faulty operation and there was a
"sweet" range for the PSU 5v that varied from machine
to machine. The big PCBs and high currents at 5v often
meant that even with PSU of 5.6v or so some logic
ships on the far side of the big PCBs were running
at 4.8v where the closer ones were running 5.3v,
and there were significant IR losses over the
connectors which often cooked and needed replacing.

The fact you said there are TWO 5v regulators in
simple parallel and a dodgy sounding diode to jack
up the voltage to 5.8v reminds me of these '80s
designs.

I really suggest using the voltage is was built
for, or maybe setting up a LM317/350 with a trimpot
to give 5v-6v adjustable and finding the ideal
voltage between the low-V and high-V failures.
On the other hand, if this is just a PSU for
general 5v use you need to set it up for your
target device.
-Roman

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