Philips 8833MK2 Electrical problems

[Interceptor]

not sure if anyone here is gonna know this or not..but here 'tis:

i have 2 8833MK2 Monitors with faults.

1) just makes this sqeual noise when i switch it on....and no light comes on. if i switch it off the squeal sort of tones down...best descibed as the sound of a missile/bomb falling is produced on a wristwatch beeper....?

2) makes that 'kin loud electrical POP short out sort of noise over and over...pop...pop....pop...pop...and the light comes in sometimes for a breif moment...as if it's shorting out or something..

no odd smells or anything though...

i'm guessig they are PSU/power switch faults right? common problems with hese montiors? any tips for fixing it, dont really want to pay £30 a time to get it fixed when i picked them up for less than a tenner each...

[lopos2000]

Sound to to me the High Voltage power supply to the tube is gone. I think you better try to get another Monitor. They are expensive to replace.

[Interceptor]

Originally Posted by lopos2000

Sound to to me the High Voltage power supply to the tube is gone. I think you better try to get another Monitor. They are expensive to replace.

sorry yeah, that's 2 seperate monitors, with 2 seperate problems. which one are you referrng to?

i do have another one, which works, but it's the old banger one with loosed plugs and stuck power switch and broken speaker

[lopos2000]

Originally Posted by Interceptor

2) makes that 'kin loud electrical POP short out sort of noise over and over...pop...pop....pop...pop...and the light comes in sometimes for a breif moment...as if it's shorting out or something..

no odd smells or anything though...

Yes, i mean this one. You could try checking the inside (of cause switch off and waiting for the HV PSU to discharge) and see how dusty is it inside and try to clean it. That my help. But my guess is the HV PSU had it.

Originally Posted by Interceptor

not sure if anyone here is gonna know this or not..but here 'tis:

i have 2 8833MK2 Monitors with faults.

1) just makes this sqeual noise when i switch it on....and no light comes on. if i switch it off the squeal sort of tones down...best descibed as the sound of a missile/bomb falling is produced on a wristwatch beeper....?

Do you get a picture when you switch it on? If you get a picture than it's not the HV PSU.

[Jope]

Originally Posted by Interceptor

1) just makes this sqeual noise when i switch it on....and no light comes on. if i switch it off the squeal sort of tones down...best descibed as the sound of a missile/bomb falling is produced on a wristwatch beeper....?

The power supply is broken and makes this sound. I haven't repaired one of these, I've always pulled one from an otherwise broken 1084. :-D

It's nicely modular in the old monitors, just press a clip on the bottom of the case and slide the PSU out. (with the back cover open of course)

2) makes that 'kin loud electrical POP short out sort of noise over and over...pop...pop....pop...pop...and the light comes in sometimes for a breif moment...as if it's shorting out or something..

It could be that the flyback (HV) transformer's casing is cracked and it's arching to the aluminium shield that surrounds it. Some people have had varying success of repairing them with epoxy, but your best bet is to get a replacement flyback.

And always remember to excercise much caution when working with monitors/TVs. Don't put your fingers under the suction cup, unless you've discharged it first! Don't prod aroud with your fingers, use a plastic/wooden stick..

[Chain]

service manual:
http://www.funet.fi/pub/msx/mirrors/...pscm8833sm.pdf

[lopos2000]

@Chain
Thanks for the link. Was looking all over the place for that.

[zipper]

Originally Posted by Interceptor

2) makes that 'kin loud electrical POP short out sort of noise over and over...pop...pop....pop...pop...and the light comes in sometimes for a breif moment...as if it's shorting out or something..

I once had a telly that had a broken solder joint on some electrolytic cap with
similar pops and flashing. Resoldering did cure it.

[Interceptor]

i'll check these out, thanks.

i once opened a monitor shortly after it stopped working, and stuck my screwdriver around, and it went bang up the screwdriver and i nearly shit myself and died.

which is how i learnt about letting them discharge...i'm now reluctant to open the thing up to see what's popping. if i cant see it without powering it up, i'lll let it rest.

but it sounds like i can take the PSU from the popping one and put it in the sqealing one and get one of them working. then bin the other one....after powering it up to see what bizzare sounds it makes then

[zipper]

Originally Posted by Interceptor

i'll check these out, thanks.

i once opened a monitor shortly after it stopped working, and stuck my screwdriver around, and it went bang up the screwdriver and i nearly shit myself and died.

I did kind of the same; I very well know where the high voltage is but my screwdriver slipped on the power section and I managed to create a quite loud pop as I fried a biggish diode which was also quite pricey.

[a_petri]

Originally Posted by Interceptor

not sure if anyone here is gonna know this or not..but here 'tis:

2) makes that 'kin loud electrical POP short out sort of noise over and over...pop...pop....pop...pop...and the light comes in sometimes for a breif moment...as if it's shorting out or something..

no odd smells or anything though...

You can try to look at this monitor *in complete darkness*. If the POPping sound is caused by a high voltage arc around the flyback transformer, there is a good chance that you'll see brief flashes of light, simultaneously with the POPs. They may be even visible with an unopened case... that's why a complete darkness is preferred.

If the POPs are caused by HV arcing, then the monitor is practically busted. There are temporary stopgap methods (like pouring some epoxy around the places where the high voltage is arcing through) but it is much safer in the long run to dispose of this monitor (and maybe salvage its power supply board for fixing the other one, as suggested).

[Overdoc]

The first one could have a shorted flyback or also shorted HV power transistor. In that case the psu is overloaded and produces the high pitched sound. So, I would try swapping psus over from the second to the first one to see if the psu of the first one is broken or just overloaded ?!