A PC & VDU seem to have related problems:

The VDU click-sounds & power-light-flashes at approx. 1 Hz before
it's usable. More so in colder weather. Now [in s. hemisphere winter]
it never reaches the threshold.

Q - is this apparent 'warm up threshold' adjustable inside the VDU ?

I've replace the VDU - for possible later summer use;
BUT the previously existing 'difficult to start PSU', now is a 'refusal to
start PSU' -- also when I disconnect the replacement VDU.

Q - what tests/measurements can I make to debug this problem ?

A PC & VDU seem to have related problems:
The VDU click-sounds & power-light-flashes at approx. 1 Hz before
it's usable. More so in colder weather. Now [in s. hemisphere
winter]
it never reaches the threshold.
Q - is this apparent 'warm up threshold' adjustable inside the
VDU ?

First, I am going to assume this is a CRT, not an LCD.

Yes.

This is not an intended "warm up". The clicking is typically
relays adjusting settings to the horizontal/vertical
frequency given in the signal from the graphics card.

It should stabilize in less than a second. I would suspect
electrolythe capacitors, that have aged enough to need some
time to recover capacity (they do that to some degree when
voltage is applied, faster so at higher temperatures because
it is a chemical process). The way to fix this is tho find
the proken capacitors and replace them. The poblem is identifying
them. Without a high-quality capacitor evaluation meter that
supports in circuit evaluation (i am nor sure these
3even exist....) this may take forever, as you
have to remove every electrolyte capacitor and assess it.

Perhaps a visual will reveal the bad elco.

I've replace the VDU - for possible later summer use;
BUT the previously existing 'difficult to start PSU', now is a
'refusal to
start PSU' -- also when I disconnect the replacement VDU.

I asume you mean the PSU of the VDU.

This is not a start
issue of the VDU-PSU. It is a stability problem. The other
characteristic of aged capacitors is that the problem
gets worse when they are not used. Don't get me wrong, they
do degrade faster when used, but the level they perform at
degrades to some lower point and stabilizes there when they
have not been used for some time.

When after running constantly for months, it's difficult to restart

Q - what tests/measurements can I make to debug this problem ?
Classical TV repair manuals may help. Significant electronics
experience is required. I would say this can be a >20 Hours job for
somebody without the right experience, but with significant
electronics knowledge. Oh, and BTW, measurements on a live CRT are
dangerous unless you know what you are doing. There are a lot of
desings out there that can have twice the mains voltage as DC on the
chassis. That can be 600V. Then there is the high voltage to the CRT
(20'000-30'000V for color) that has quite a punch behind it, since the
CRT acts as capacitor. Not as bad as touching the wires on a medium
voltage (typically 15'000V, but with far higher currents), power
delivery line, but can still kill you. Definitely a ''stay away''
zone.

Yes, I don't probe near ETH.

I would advise you to get a new LCD instead. If you stay at
17" (screen space comparable to 19" CRT), you can get decent
ones pretty cheap.

In comp.sys.ibm.pc.hardware.misc problems at (no spam) gmail wrote:

Arno Wagner wrote:
First, I am going to assume this is a CRT, not an LCD.

Yes.

.....
OK, on a good VDU I notice the power/screen-save mode
time-out & re-activate toggles this. So I could just hack the
VDU's circuit to have it permanently 'on'.

Beware. The relay is triggered by some safety circuit as well. It turns off

It should stabilize in less than a second. I would suspect
electrolythe capacitors, that have aged enough to need some
time to recover capacity (they do that to some degree when
.....

Perhaps a visual will reveal the bad elco.
Or just replace some/all.

These are special elkos, you won't find them in the next hardware store.

I asume you mean the PSU of the VDU.

No it's the PC PSU.

Well, the first troubles were the CRT PSU - now it is coincidence time ...

When after running constantly for months, it's difficult to restart
after it's been off for a day; and starting is erratic you first suspect
temperature or a possible mains fluctuation. Ie. some parameter
which can vary over 24 hours. But I guess it's another dud elco.
I'd much prefer to bypass the troublesome feedback loops and
just have a direct mains switch, like in the old days.

Open the case, reseat your connectors.

In comp.sys.ibm.pc.hardware.misc problems at (no spam) gmail wrote:
A PC & VDU seem to have related problems:
The VDU click-sounds & power-light-flashes at approx. 1 Hz before
it's usable. More so in colder weather. Now [in s. hemisphere
winter]
it never reaches the threshold.
Q - is this apparent 'warm up threshold' adjustable inside the
VDU ?

Arno Wagner wrote:
First, I am going to assume this is a CRT, not an LCD.

Yes.

This is not an intended "warm up". The clicking is typically
relays adjusting settings to the horizontal/vertical
frequency given in the signal from the graphics card.

OK, on a good VDU I notice the power/screen-save mode
time-out & re-activate toggles this. So I could just hack the
VDU's circuit to have it permanently 'on'.

It should stabilize in less than a second. I would suspect
electrolythe capacitors, that have aged enough to need some
time to recover capacity (they do that to some degree when
voltage is applied, faster so at higher temperatures because
it is a chemical process). The way to fix this is tho find
the proken capacitors and replace them. The poblem is identifying
them. Without a high-quality capacitor evaluation meter that
supports in circuit evaluation (i am nor sure these
3even exist....) this may take forever, as you
have to remove every electrolyte capacitor and assess it.

Perhaps a visual will reveal the bad elco.

Or just replace some/all.

I've replace the VDU - for possible later summer use;
BUT the previously existing 'difficult to start PSU', now is a
'refusal to
start PSU' -- also when I disconnect the replacement VDU.

I asume you mean the PSU of the VDU.

No it's the PC PSU.

This is not a start
issue of the VDU-PSU. It is a stability problem. The other
characteristic of aged capacitors is that the problem
gets worse when they are not used. Don't get me wrong, they
do degrade faster when used, but the level they perform at
degrades to some lower point and stabilizes there when they
have not been used for some time.

When after running constantly for months, it's difficult to restart
after it's been off for a day;

and starting is erratic you first suspect
temperature or a possible mains fluctuation. Ie. some parameter
which can vary over 24 hours. But I guess it's another dud elco.
I'd much prefer to bypass the troublesome feedback loops and
just have a direct mains switch, like in the old days.

Q - what tests/measurements can I make to debug this problem ?
Classical TV repair manuals may help. Significant electronics
experience is required. I would say this can be a >20 Hours job for
somebody without the right experience, but with significant
electronics knowledge. Oh, and BTW, measurements on a live CRT are
dangerous unless you know what you are doing. There are a lot of
desings out there that can have twice the mains voltage as DC on the
chassis. That can be 600V. Then there is the high voltage to the CRT
(20'000-30'000V for color) that has quite a punch behind it, since the
CRT acts as capacitor. Not as bad as touching the wires on a medium
voltage (typically 15'000V, but with far higher currents), power
delivery line, but can still kill you. Definitely a ''stay away''
zone.

Yes, I don't probe near ETH.

I would advise you to get a new LCD instead. If you stay at
17" (screen space comparable to 19" CRT), you can get decent
ones pretty cheap.

Thanks. Remember that inet is global; so I might be writing for
some remote island, which has a different price structure to the
US. That's why the US got it's arse kicked in Iraqu: because they
simplictically believed that all conditions are like their's.

This is not an intended "warm up". The clicking is typically
relays adjusting settings to the horizontal/vertical
frequency given in the signal from the graphics card.
OK, on a good VDU I notice the power/screen-save mode
time-out & re-activate toggles this. So I could just hack the
VDU's circuit to have it permanently 'on'.
That could work, if there there is no frequency
adjustment involved, or you fix it to the right setting
there as well.

So your PC PSU has an issue as well?

This is not a start
issue of the VDU-PSU. It is a stability problem. The other
characteristic of aged capacitors is that the problem
gets worse when they are not used.