25 Nov
2023
25 Nov
'23
10:34 p.m.
On Sat, Nov 25, 2023 at 11:12 PM Rob Jarratt
<robert.jarratt(a)ntlworld.com> wrote:
Without the schematic you are going to have problems.
With a schematic you can see
(a) Can you isolate certain areas -- for example the vertical deflection syste
It gets easier with experience. Looking at every small monochrome
monitor schematic you can find will give you an idea of the sort of
things to look for.
The high voltage outputs can't supply that much current and are
unlikely to be lethal. Mains, and even worse the rectified mains in an
SMPSU, is a lot more liely to kill you.
That said, work with one hand in your pocket (current flow arm-to-arm
is the most dangerous) and take care.
I don't see how you can debug a monitor without having the flyback in
place. It's part of the highest power circuit on the board. And it
provides voltages for many other areas.
-tony
Have you
checked the diodes and capacitors associated with the flyback
transformer? If something is shorted there. it's the equivaent of running a
power supply into a short circuit. The input current will go up.
I have checked all the diodes (in circuit) and they appear to be OK. One capacitor may be
suspect but without the full schematic I am not sure. I may have to lift it to check.
Trace out a
schematic of the board so I know what I am dealing with.
Yes, I may have to do that. Historically I have done a poor job of this because of my
insufficient understanding of electronics. I do wonder
what the problem is with testing it with the flyback connected,
though...
Only that I know it can produce lethal voltages and I would rather avoid that if I can.