I recently got an ancient monochrome video monitor from a friend.

This thing probably hasn't been powered on for fifteen or twenty years.
I'm thinking I will put it on a variac and turn it up slowly from zero
over several hours, to maybe let electrolytic caps reform, and avoid
anything else that might object to getting suddenly whacked with a full
120 volts. Is that a good idea? Is there anything in a video monitor,
like maybe the high voltage supply, that will object to running on
reduced voltage for a few hours at first?

"David Harmon" wrote in message
...
I recently got an ancient monochrome video monitor from a friend.

This thing probably hasn't been powered on for fifteen or twenty years.
I'm thinking I will put it on a variac and turn it up slowly from zero
over several hours, to maybe let electrolytic caps reform, and avoid
anything else that might object to getting suddenly whacked with a full
120 volts. Is that a good idea? Is there anything in a video monitor,
like maybe the high voltage supply, that will object to running on
reduced voltage for a few hours at first?

**Very risky. The thing may use a SMPS. It will certainly use an LOPT driven
by a high frequency oscillator, which may or may not start, when gradually
ramped up. You may end up causing more damage. Or not. It's a crap shoot
IMO.

Trevor Wilson

"Trevor Wilson" writes:

"David Harmon" wrote in message
...
I recently got an ancient monochrome video monitor from a friend.

This thing probably hasn't been powered on for fifteen or twenty years.
I'm thinking I will put it on a variac and turn it up slowly from zero
over several hours, to maybe let electrolytic caps reform, and avoid
anything else that might object to getting suddenly whacked with a full
120 volts. Is that a good idea? Is there anything in a video monitor,
like maybe the high voltage supply, that will object to running on
reduced voltage for a few hours at first?

**Very risky. The thing may use a SMPS. It will certainly use an LOPT driven
by a high frequency oscillator, which may or may not start, when gradually
ramped up. You may end up causing more damage. Or not. It's a crap shoot
IMO.

Agreed. Just apply normal power. At least you'll know pretty quickly
if something's going to blow up.

It may be OK if it wasn't used over that time and was stored in a cool place.

To be doubly sure, you could check the ESR of electrolytic caps in the
power supply and deflection, and/or simply replace the main filter caps.

How important is it to get the monitor going?

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
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| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
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Sam Goldwasser wrote:
Agreed. Just apply normal power. At least you'll know pretty quickly
if something's going to blow up.

Also, some old PC monitors rely on receiving sync from the computer's
video adaptor before generating EHT etc. Running at a reduced supply
will most likely not allow the interface circuitry to function to allow
sync through.

--
Adrian C

Hi!

I recently got an ancient monochrome video monitor from a friend.

I think it might be OK to just plug it in, turn it on and go. I've done
exactly that with a number of old monitors that had been sitting for a long
time and had no problems. The overwhelming majority of "duds" were a result
of picture tubes that had simply been "used up" before the monitor was taken
out of service. I don't remember any offhand that died upon power-on.

As has been mentioned, some monitors have switch mode power supplies. These
may be stressed by low line voltage and they could fail either immediately
or after running for a while.

William

David Harmon wrote:

I recently got an ancient monochrome video monitor from a friend.

This thing probably hasn't been powered on for fifteen or twenty years.

If it isn't vacuum-tube (valve) based, it really isn't ancient, and even
then if it dates from the late '60s or newer it really isn't ancient ;-).

Why would you worry about applying power to a 20 year-old monitor? For
*od's sake, that would have only have been 1987. A soft start using
a ferro-resonant isolation transformer or perhaps a continuous-duty
UPS would prevent transient or large inrush problems but I really wouldn't
worry too much ;-)

OTOH, if it has a round CRT and uses a 6BQ6 sweep tube, I'd use a variac.

Regards,

Michael

On 06 Nov 2007 19:08:37 -0500 in sci.electronics.repair, Sam Goldwasser
wrote,
Agreed. Just apply normal power. At least you'll know pretty quickly
if something's going to blow up.

OK, that's what I will do.

How important is it to get the monitor going?

If it works I can get rid of an even older monitor; that one's a Ball
with a steel box 22"x20"x20" weighs probably 100lbs (I barely lift it)
and has airline arrivals and departures burned in to the phosphor.

"David Harmon" wrote in message
...
I recently got an ancient monochrome video monitor from a friend.

This thing probably hasn't been powered on for fifteen or twenty years.
I'm thinking I will put it on a variac and turn it up slowly from zero
over several hours, to maybe let electrolytic caps reform, and avoid
anything else that might object to getting suddenly whacked with a full
120 volts. Is that a good idea? Is there anything in a video monitor,
like maybe the high voltage supply, that will object to running on
reduced voltage for a few hours at first?



Just plug it in. If it were 50 years old I'd say use a variac, but 20 years
is not that long, the components will be relatively modern.

David Harmon wrote:
I recently got an ancient monochrome video monitor from a friend.

This thing probably hasn't been powered on for fifteen or twenty years.
I'm thinking I will put it on a variac and turn it up slowly from zero
over several hours, to maybe let electrolytic caps reform, and avoid
anything else that might object to getting suddenly whacked with a full
120 volts. Is that a good idea? Is there anything in a video monitor,
like maybe the high voltage supply, that will object to running on
reduced voltage for a few hours at first?

connect a light globe in the active lead of a power lead and then switch
it on. This technique is useful when repairing/testing monitors.

Andrew

David Harmon writes:

On 06 Nov 2007 19:08:37 -0500 in sci.electronics.repair, Sam Goldwasser
wrote,
Agreed. Just apply normal power. At least you'll know pretty quickly
if something's going to blow up.

OK, that's what I will do.

How important is it to get the monitor going?

If it works I can get rid of an even older monitor; that one's a Ball
with a steel box 22"x20"x20" weighs probably 100lbs (I barely lift it)
and has airline arrivals and departures burned in to the phosphor.

I recall using ones like that. They were really nice monitors.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.

"msg" wrote
Why would you worry about applying power to a 20 year-old monitor? For
*od's sake, that would have only have been 1987. A soft start using
a ferro-resonant isolation transformer or perhaps a continuous-duty
UPS would prevent transient or large inrush problems but I really wouldn't
worry too much ;-)

Dust could be a problem around the EHT.

How do I know this?

I know this because just this last Saturday, I lost a 21" Iiyama
monitor that I paid about 650 GBP for about 6 years ago.

I'd known it'd been on its way out for months because sometimes
it would spark over inside and the picture would change to a bright
vertical line in the centre. I assumed it was caused by dust around
the EHT. I'd switch it off, wait for a few seconds, back on again, and
it'd usually be ok.

Of course this sparking chars the dust and leaves conductive carbon
around the EHT area.

On Saturday morning, what I knew was gonna happen happened. I
switched it on, and there was a *poooufff* - not that loud - but
unlike anything I'd heard it do before.

Lights out - forever.


Martin - I'm not bitter, Sassnfrassnsonofabitchstoopiddog****goddamnmofo... .
--
M.A.Poyser Tel.: 07967 110890
Manchester, U.K. http://www.livejournal.com/userinfo.bml?user=fleetie

"Fleetie" wrote in message
...
"msg" wrote
Why would you worry about applying power to a 20 year-old monitor? For
*od's sake, that would have only have been 1987. A soft start using
a ferro-resonant isolation transformer or perhaps a continuous-duty
UPS would prevent transient or large inrush problems but I really
wouldn't
worry too much ;-)

Dust could be a problem around the EHT.

How do I know this?

I know this because just this last Saturday, I lost a 21" Iiyama
monitor that I paid about 650 GBP for about 6 years ago.

I'd known it'd been on its way out for months because sometimes
it would spark over inside and the picture would change to a bright
vertical line in the centre. I assumed it was caused by dust around
the EHT. I'd switch it off, wait for a few seconds, back on again, and
it'd usually be ok.

Of course this sparking chars the dust and leaves conductive carbon
around the EHT area.

On Saturday morning, what I knew was gonna happen happened. I
switched it on, and there was a *poooufff* - not that loud - but
unlike anything I'd heard it do before.

Lights out - forever.




Dust didn't do that, a cracked solder joint in the horizontal deflection
area did. The obvious clue is the lack of deflection when it acted up. 5
minutes with a soldering iron *before* the HOT and possibly other components
blew would have saved your monitor.

On Nov 8, 9:28 pm, "Fleetie" wrote:
"msg" wrote

Why would you worry about applying power to a 20 year-old monitor? For
*od's sake, that would have only have been 1987. A soft start using
a ferro-resonant isolation transformer or perhaps a continuous-duty
UPS would prevent transient or large inrush problems but I really wouldn't
worry too much ;-)

Dust could be a problem around the EHT.

How do I know this?

I know this because just this last Saturday, I lost a 21" Iiyama
monitor that I paid about 650 GBP for about 6 years ago.

I'd known it'd been on its way out for months because sometimes
it would spark over inside and the picture would change to a bright
vertical line in the centre. I assumed it was caused by dust around
the EHT. I'd switch it off, wait for a few seconds, back on again, and
it'd usually be ok.

Of course this sparking chars the dust and leaves conductive carbon
around the EHT area.

On Saturday morning, what I knew was gonna happen happened. I
switched it on, and there was a *poooufff* - not that loud - but
unlike anything I'd heard it do before.

Lights out - forever.

Martin - I'm not bitter, Sassnfrassnsonofabitchstoopiddog****goddamnmofo... .
--
M.A.Poyser Tel.: 07967 110890
Manchester, U.K. http://www.livejournal.com/userinfo.bml?user=fleetie

that just shows why you shouldn't nurse intermittent faults like that
along. by the way this is nothing to do with dust, it is a bad solder
joint. In carrying on using it you have stressed the scan circuits and
finally they gave up the ghost..... A waste of a good repairable
monitor. hope that serves as a lesson to you....
-B

On 06 Nov 2007 19:08:37 -0500 in sci.electronics.repair, Sam Goldwasser
wrote,
Agreed. Just apply normal power. At least you'll know pretty quickly
if something's going to blow up.

By the way, it worked fine.

Dust didn't do that, a cracked solder joint in the horizontal deflection
area did. The obvious clue is the lack of deflection when it acted up. 5
minutes with a soldering iron *before* the HOT and possibly other components
blew would have saved your monitor

I've had two Iiyama monitors with that fault. Just needed to get
underneath the main circuit board and resolder the connectors to the
scan coils.