Hitachi CM813ET image jitter

Having turned the monitor back on and with the jitter continuing, I should restate this part. The jitter is not quite so high frequency as to put each line at a random position wrt other lines. Looking at the right side of the screen, the wavelength of the wave inherent in the supposedly straight right side edge is about 1-2 cm on average, putting around 20-30 waves per redraw, putting the wobbling frequency around 2 kHz. I don't know if this is relevant in any way, but I didn't want anyone to make conclusions based on bad information.

Just to make a comment, this is one big long description! And, it is well written. Have you thought of taking up literature, at the professional level?

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This is not the type of fault that can be analysed over an email. The fault would only be able to be found by verifying voltages, and observing for the proper waveforms or looking for noise in the supplies to the various circuits.

to open bypass capacitors, or there may be some arching in a component somewhere.

There is no way to accuratly tell you an exact fix. This is where a properly trained skilled technician, who has the proper diagnostics equipment, would have to work on the monitor.

One big problem with the computer monitors, is that the manufactures will not sell service parts, or schematic diagrams to non-authorised factory service techs.

If you call Hitachi, and ask about who is servicing their computer monitors, I am sure that they will recomend where to bring it.

If the monitor is about or more than 5 years of age, I would strongly recomend that you start shopping for a new one. I would not put a lot of money in to an old CRT monitor. These can be now purchased at a very low price in relation to the cost of servicing them.

Jerry G. ======

This is definitely something I have to check. Brightness is pretty much the only adjustment I haven't tried so far. Right now the monitor isn't exhibiting the symptoms, but I shall check this out when the problem inevitably returns.

I must say that I haven't smelled anything out of the ordinary. Nothing in the very familiar ozone smell range anyway. I haven't noticed any problems with RF reception either, nor do I remember hearing any crackling from the monitor. I'll have to recheck all that though just to be sure.

True. My intention is to at some point open the case and use cold spray to find any such heat sensitive components. There are, however, a lot of components in a monitor, making it rather difficult to just start spraying around, which is why I would have been interested in learning of any starting spots anyone could suggest.

I have fixed amplifiers and such in the past and done some focus tuning to older monitors, and for those have spent considerable time learning about the hazards of CRT monitors. I know where the dangerous parts are and would rather read 10 books to find out about a component rather than poking it with my finger to see what happens. This echoing the reasons for writing here before even opening the case up so that I would have some idea of what to look for.

Jerry G, thank you for your compliment. I like to write clear descriptions because it not only helps others understand the problem precisely, it also helps me outline the problem for myself. I bought the monitor a couple of months ago used for about 100 EUR. According to the backplate it's built in '99. Its history is such that the person I bought it from had gotten it from his workplace where it had shown the symptoms. He took it home and never had any problems with it. After I brought it home, the problems were there, but were so rare that I figured it was still worth the price I paid for it (this monitor has _excellent_ image quality!) so we agreed that I'd be keeping it regardless of the problems. I might still be able to take it back, but I'm not sure if I want to. Nevertheless, considering this person never had any problems, it would seem that humidity or some other environmental aspect could indeed play a major role here. I could take it to be repaired, but as you said, it would probably cost way too much. Being the student that I am, I don't really have all that much spare cash lying around to spend on this project or on a new monitor.

You guys have helped me already, particularly by mentioning the possibility of arcing. I have a good multimeter and I can get my hands on an oscilloscope if I need to. If it is about arcing though, I'd imagine that in the best case scenario the whole problem can be fixed by a piece of insulating tape somewhere.

Please do let me know if you have any further suggestions.

Now this is what I came here for, and then some! Thank you Asimov. Now I have something very concrete to go by. If you ever visit Finland, look me up and you shall not be short of beer.