Hello,

My old (1994 mfg) 21" DEC digital monitor was screaming/whistling when i
went to log on this morning not loud but annoying high pitch about
frquency/pitch ? of whistling through teeth. there were *no* power indicator
lights (eg. amber for low power sleep mode and green for active ). i turned
it off few minutes turned it on and same whistle immediately with no flash
flicker from screen or power lights. of course immediatelt turned it off

my first guess is some internal switching power supply problem maybe ( just
from symptoms) ???

Any ideas about what i could do to repair ? *OR*
should i seek professional help because i might kill myself trying to
repair this ? *OR*
should i just toss it ?

thanks for any help to my (1) primery concern prevent killing myself and
to my (2) secondary concern repair
rob

robb wrote:
Hello,

My old (1994 mfg) 21" DEC digital monitor was screaming/whistling when i
went to log on this morning not loud but annoying high pitch about
frquency/pitch ? of whistling through teeth. there were *no* power indicator
lights (eg. amber for low power sleep mode and green for active ). i turned
it off few minutes turned it on and same whistle immediately with no flash
flicker from screen or power lights. of course immediatelt turned it off

my first guess is some internal switching power supply problem maybe ( just
from symptoms) ???

Any ideas about what i could do to repair ? *OR*
should i seek professional help because i might kill myself trying to
repair this ? *OR*
should i just toss it ?

thanks for any help to my (1) primery concern prevent killing myself and
to my (2) secondary concern repair
rob

Hi, Rob. Your reluctance to dig into this is telling you something
(Examine your feelings, Luke). Very high voltage, potentially lethal.
You got 12 good years out of your monitor. Time for an upgrade.
Unless you're experienced with high voltage repairs, just toss it.

Good luck
Chris

I heard tales that they would refurb tek scopes by washing them in
distilled water. The HV static electricity attracts dust, which is
conductive to some degree, and causes arcs and sparks. So hose it down,
give it a few minutes with the hair dryer, and if its as good as new,
it might last another couple years. Good luck. Unplug it first.

BobG wrote:
I heard tales that they would refurb tek scopes by washing them in
distilled water. The HV static electricity attracts dust, which is
conductive to some degree, and causes arcs and sparks. So hose it down,
give it a few minutes with the hair dryer, and if its as good as new,
it might last another couple years. Good luck. Unplug it first.

THat suggestion is surely a mischievous one. If it's 12 years old, toss
it out. The tube will be thoroughly aged by now. This is nature's way
of saying "buy a new monitor".

BobG wrote:
I heard tales that they would refurb tek scopes by washing them in
distilled water. The HV static electricity attracts dust, which is
conductive to some degree, and causes arcs and sparks. So hose it down,
give it a few minutes with the hair dryer, and if its as good as new,
it might last another couple years. Good luck. Unplug it first.

THat suggestion is surely a mischievous one. If it's 12 years old, toss
it out. The tube will be thoroughly aged by now. This is nature's way
of saying "buy a new monitor".

"Meat Plow" wrote in message
news
On Thu, 07 Dec 2006 12:34:54 +0000, robb Has Frothed:

Hello,

My old (1994 mfg) 21" DEC digital monitor was screaming/whistling when i
went to log on this morning not loud but annoying high pitch about
frquency/pitch ? of whistling through teeth. there were *no* power
indicator
lights (eg. amber for low power sleep mode and green for active ). i
turned
it off few minutes turned it on and same whistle immediately with no
flash
flicker from screen or power lights. of course immediatelt turned it off

my first guess is some internal switching power supply problem maybe
( just
from symptoms) ???

Any ideas about what i could do to repair ? *OR*
should i seek professional help because i might kill myself trying to
repair this ? *OR*
should i just toss it ?

thanks for any help to my (1) primery concern prevent killing myself
and
to my (2) secondary concern repair
rob

Unless you have sucessfully repaired a device with a switch mode power
supply and a hi volt supply capable of 30kv, stay out of it.


I have opened a couple of color TVs and lived to tell about it and once
replace two TO-2 package transistors to fix screen problems but to answer
your question no never succesfully repaired a 30kv SMP

i was hoping it might be something simple like replace the ??? whatever and
if it works great if not then stop.

I do appreciate your candid response though , i think it is sound advice.

rob


--
Pierre Salinger Memorial Hook, Line & Sinker, June 2004

COOSN-266-06-25794

"Chris" wrote in message
ups.com...

robb wrote:
Hello,

My old (1994 mfg) 21" DEC digital monitor was screaming/whistling when i
went to log on this morning not loud but annoying high pitch about
frquency/pitch ? of whistling through teeth. there were *no* power
indicator
lights (eg. amber for low power sleep mode and green for active ). i
turned
it off few minutes turned it on and same whistle immediately with no
flash
flicker from screen or power lights. of course immediatelt turned it off

my first guess is some internal switching power supply problem maybe
( just
from symptoms) ???

Any ideas about what i could do to repair ? *OR*
should i seek professional help because i might kill myself trying to
repair this ? *OR*
should i just toss it ?

thanks for any help to my (1) primery concern prevent killing myself
and
to my (2) secondary concern repair
rob

Hi, Rob. Your reluctance to dig into this is telling you something
(Examine your feelings, Luke). Very high voltage, potentially lethal.
You got 12 good years out of your monitor. Time for an upgrade.
Unless you're experienced with high voltage repairs, just toss it.

Good luck
Chris


no experience, i just know enough not to be dangerous and reckless . i
thought if it were a simple or common problem with most monitors that a
simple replace all the ??? whatever bits would probably solve then it was
worth a try

i have not looked at new monitors much but this one is nice has 15 pin and
RGB/HD inputs and can display up to 1600 x 1200 at all sorts of refresh
rates it was a great, bright , flat screen monitor with antiglare coating
lots of screen adjustment settings, adjustable cathode temp ? that came from
an old DEC 3000 graphics workstation ....

just a shame to loose it

thanks for your help
rob

robb wrote:

i have not looked at new monitors much but this one is nice has 15 pin and
RGB/HD inputs and can display up to 1600 x 1200 at all sorts of refresh
rates it was a great, bright , flat screen monitor with antiglare coating
lots of screen adjustment settings, adjustable cathode temp ? that came from
an old DEC 3000 graphics workstation ....


Sounds a bit like my 1994 Iiyama. I changed it for a 17" LCD monitor
last year. As I had a dual head display card I set them up next to each
other, and the difference was amazing. Even allowing for the different
technology, 11 or 12 years is a very long time in the life of a CRT,
as I saw! LCDs are inherently free of geometry distortions and focus
problems. My Iiyama had a very slight residual barrel distortion that I
was never able to get rid of.

"robb" wrote in message
news



I have opened a couple of color TVs and lived to tell about it and once
replace two TO-2 package transistors to fix screen problems but to answer
your question no never succesfully repaired a 30kv SMP

There have been lots of threads in the past about high-pitched sounds
emanating from CRT-based devices, do some googling.

The SMPS is not 30kV, that'd be the HV output of the flyback. You don't
want to work on it live.

wrote in message
ups.com...

Sounds a bit like my 1994 Iiyama. I changed it for a 17" LCD monitor
last year. As I had a dual head display card I set them up next to each
other, and the difference was amazing. Even allowing for the different
technology, 11 or 12 years is a very long time in the life of a CRT,
as I saw! LCDs are inherently free of geometry distortions and focus
problems. My Iiyama had a very slight residual barrel distortion that I
was never able to get rid of.

I just upgraded my monitor to a 19" LCD. All I can say is I should've done
it sooner, the difference is a-mazing. It's bright, there's zero glare, it
comes on instantaneously, overall it's much much easier on the eyes.

Dave

"robb" wrote in message
ink.net...

My old (1994 mfg) 21" DEC digital monitor was screaming/whistling when i
went to log on this morning not loud but annoying high pitch about
frquency/pitch ? of whistling through teeth.

The flyback is running way off frequency.

Try for a free monitor on

http://freecycle.org/

or

http://www.craigslist.org/

and save a working unit from the waste stream.

and the LCD will save you much money on power utilitie bill.

older monitors are GREAT heaters though ;-))

you may recoup your LCD cost within two years just from the power company
savings!


"Dave" wrote in message
news:clXdh.31486$hn.7154@edtnps82...

wrote in message
ups.com...

Sounds a bit like my 1994 Iiyama. I changed it for a 17" LCD monitor
last year. As I had a dual head display card I set them up next to each
other, and the difference was amazing. Even allowing for the different
technology, 11 or 12 years is a very long time in the life of a CRT,
as I saw! LCDs are inherently free of geometry distortions and focus
problems. My Iiyama had a very slight residual barrel distortion that I
was never able to get rid of.

I just upgraded my monitor to a 19" LCD. All I can say is I should've
done
it sooner, the difference is a-mazing. It's bright, there's zero glare,
it
comes on instantaneously, overall it's much much easier on the eyes.

Dave

robb ha escrito:
Hello,

My old (1994 mfg) 21" DEC digital monitor was screaming/whistling when i
went to log on this morning not loud but annoying high pitch about
frquency/pitch ? of whistling through teeth. there were *no* power indicator
lights (eg. amber for low power sleep mode and green for active ). i turned
it off few minutes turned it on and same whistle immediately with no flash
flicker from screen or power lights. of course immediatelt turned it off

possible short in the horizontal output - I have seen whistling
monitors with this. could be a problem in the line o/p transformer /
transistor, and the power supply is in protection mode.

if you can solder, i would start by desoldering the line o/p
transistor and connecting a 60-100w bulb across c-e, see if it
lights , to check you have b+.

if you opt for that, leave the unit unplugged a couple of days then :
1. stay away from the mains filter capacitor and power supply
2. dont tamper with the big fat red wire which goes to a rubber cup on
the tube

In my experience, actuall disassembling the unit enougjh to get to the
soldered side of the pcb is the most problematic - compared to TVs
they are a nightmare!

In any case it may be worth a shot before tossing it...who knows you
may learn something.- if it doesn't work out i also recommend
freecycle. people usually have tons of monitors to give away, and you
can save em from the landfill.
-B