x68000 monitor black line

[msx33]

While I am using my x68000 crt aftr a while, there is a black line blinking that can appear on the top of the screen. It is minor, but the quality of the screen is so good in comparison, that it look like a spot in a middle of the rest. It became annoying for me.
Sometime it go off when I used the  monitor screen adjustement but come back on the next game or the next minute.
It is hard to determine under what circonstance it occurs. On some game it won't happen ,on others it will but not all the time.

Any idea what could this come from? Capacitors? Any way to fix this?

Because I wonder if I am not a get a new monitor if this can not be solved in order to get a crystal clear quality image.

Thank you

[eidis]

Replace capacitors and see if it helps.

Eidis

Update: The black line could be linked to synchronization issues. I have something similar on my arcade machine. Sometimes the image at the very top of the screen gets distorted by a grey line, just if the synchronization was slightly misaligned. The picture there can be seen, but without colors and is slightly skewed.  Usually this can be adjusted with the synchronization potentiometer which is inside the monitor, however the problem it self could be caused by old capacitors which do not meet their original specifications due to age.

[msx33]

Thank you for your complete reply.

I used it again since, and I didn't see any line this time after more than an hour of gaming. If I a find out more, I will post.

Whatever the reason is I don't think I will open my monitor due to the hight voltage risk. In the worst case I will make it repair.

[eidis]

 Msx33,

Here's a true story about old capacitors. My ACE HD had faulty floppy drives. At first they did not read floppy's but after approximately 15 minutes everything started working like a charm. They could work for as long as the system had uninterrupted power. After replacing capacitors on the floppy drive PCB's the problem was gone.

Don't take this problem lightly. The main purpose of capacitors is to make power smooth and filter out spikes in electricity. Your monitor is giving you early warnings that something will break. Right now it is just a simple recap issue which could grow into a not so nice situation if left untreated.

I recapped my arcade monitor recently and could give you some hints. Flip monitors power switch to on and unplug it from the mains socket. Let it sit for one hour, that should discharge it. Carefully open the case and write down the capacitor values. There is a strange paradox that analogue circuitry is more picky about capacitors and it is not as simple as with digital electronics. There are more values than voltage and capacity. A 16v 100uf capacitor can have different performance even if the voltage and capacity is the same. In other words, you will preferably need capacitors which comply to all markings of the original. I was lucky with Microvitec monitor, but my arcade Wells Gardner was picky.

Best of luck !
Eidis

[BlueBMW]

My Wells Gardner monitor was also pretty picky.  Even after a full recap, flyback and tune its still not quite right.  I even swapped in another tube, but I still get some jailbars and such.  I suspect I need to change some of the caps I used.

OP, definitely consider doing caps sooner rather than later.  Its a royal pain, but worth it in the end.

[eidis]

BlueBMW,

There are cap kits for sale on eBay. Could this listing be of interest to you ?

Wells Gardner K7000 Cap Kit for Monitor Repair
http://www.ebay.com/itm/200639974675?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649

Eidis