my digital monitor screaming/whistling ? help plz ?

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

Reply to
robb
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On Thu, 07 Dec 2006 12:34:54 +0000, robb Has Frothed:

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.

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

COOSN-266-06-25794
Reply to
Meat Plow

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

Reply to
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.

Reply to
BobG

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".

Reply to
mike.j.harvey

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".

Reply to
mike.j.harvey

indicator

turned

flash

( just

and

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

Reply to
robb

indicator

turned

flash

( just

and

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

Reply to
robb

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.

Reply to
mike.j.harvey

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.

Reply to
Dave

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

Reply to
Dave

On Thu, 07 Dec 2006 16:03:47 +0000, robb Has Frothed:

I know how you feel and I tend to hang onto stuff forever as long as my girlfriend doesn't bug me about tossing it :) But at 12 years old, I think it's time to just replace yours since it's well served its purpose. I recently replaced an old Emerson 15" monitor that I got used and non working back in 1995. If you would take the monitor out of its scan range rather than it just shutting down it would blow the HOT immediately. But for what I used it for it was perfect. I bought a 17" use TFT monitor for $50 bucks to replace it.

Reply to
Meat Plow

The flyback is running way off frequency.

Try for a free monitor on

formatting link

or

formatting link

and save a working unit from the waste stream.

Reply to
Homer J Simpson

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!

done

it

Reply to
<hapticz

robb ha escrito:

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

Reply to
b

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