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G2 is independent of HV. If HV were too high then the monitor would simply shut down.
You may be on to something here. I'll check it out these days, unfortunately i haven't had time to mess with it yet. Could you give me a link to the service manual?
That would be horizontal output transistors. (HOTs) While it is true that the flyback transformer itself gets a bit hotter with higher frequencies, it's the horizontal output transistor (the big one which switches B+ into the flyback) which becomes more and more inefficient as frequency rises.
It's not, and this time it really has to do with the flyback. All transformers have a minimum operating frequency depending on core material, size of air gap and number of primary turns. If the frequency is too low, the core saturates. If the core would be allowed to saturate the HOT would blow up.
MAY THE SOFTWARE BE WITH YOU!
I CYBERYOGI Christian Oliver(=CO=) Windler I
I (teachmaster of LOGOLOGIE - the first cyberage-religion!) I
I ! I
Yes, but high brightness means more electrons hit the screen while the statistical amount of xray photons per electron stays constant =>more xray.
The file name is "GDM-5411.pdf". You can get it e.g. from here:
I always wondered why multiscan monitors don't simply use separate oscillators for horizontal deflection and flyback input. So the flyback trafo could always run on its optimal frequency and waste less energy.
That link sent me to an ugly little exe file. Anyway, i just remembered i had it - just have to look up the correct section.
If they ran at different frequencies they would interfere with one another, the result being ugly distortions of the picture.
So I am not sure why this is causing this monitor to freak out, can you give me an idea what to do, am I grounding wrong or something, is this normal?
I would still need to measure the HV (~27.0 kV, would need a probe like this - would that one also work for measuring the G2, I see it has high input impedance)
I hope someone comes up with a better solution than the Windas method. I've had to lower the G2 three times so far and after the last time the monitor takes over a minute to warm up enough to see a picture.
Btw, have 100% confirmed that the bright screen before warmup is NOT a tube problem - i've had the monitor on all day and now after messing with WinDAS the screen was darker for a minute or so from when WinDAS shut it down to when it came back up - ie just like it should be. It probably traces to the same resistor people change to fix the G2 problem without using WinDAS. I'll try and take this beast apart next weekend and replace that resistor to see if the high initial brightness will be cured.
Bypassed the drift correct circuit on the P1110, upped the G2 using WinDAS to compensate. Guess what? I finally got a normal monitor! No more excessive brightness at startup, yippee!!!
The cutoff voltages of all cathodes will drift. Common drift is adjusted by the user by controlling the brightness. Different drift leads to a coloration of the black background level. In extreme cases vertical flyback lines will appear. Cutoff voltage can be adjusted with potentiometers, or there is automatic stabilisation. Still, the VG2 (screen) may need periodic adjustment too.
Some differences are normal depending on the age of the parts. One thing's for sure though: With the drift correct circuit removed, both monitors are going to start up at exactly the same brightness. Taking a few minutes to warm up and stabilize is normal, and it's inherent to all CRT displays.With my P1110 for instance, if it's been really cold (i've been out all day today), black appears slightly green at startup and hence the picture appears brighter. This normalizes in less than 10 minutes - that's lots better than having brightness drift for 2 hours.For the second monitor, you may have a problem with the power supply but it's likely something simple like a cold solder joint. I'd try and touch up the soldering, specifically all the joints around the CRT neck, all big semiconductors and relays.Since you will have to up G2 quite a bit after eliminating the drift correct circuit, make sure you adjust it so optimal picture is at 50% brightness or below. I've talked about it sometime earlier, these monitors are wired to automatically lower the contrast when you up the brightness past 50%, to keep focus in check. Trouble is, this also shifts the color balance a bit, which is annoying. Better avoid it by setting G2 so that picture is bright enough before you reach 50% brightness in the menu.Also i'm not sure anyone has mentioned this before: Always remove the ECS cable from the monitor when you're done with WinDAS. Keeping it in causes interference with the 5v rail which shows as slight wobbles in horizontal size.
Ya'll should fix my P1130. Still works, but you can see jittering in text and small lines.
(Was for running classic games on, but I can't look at CRTs anymore, too much eye damage done, strain is too much now.)
Icrontic — Home of the Big Beef Burrito since 8-8-2000, fool.
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