View Full Version : Need Help/Advice For Sony PVM


jmetal88
12-30-2013, 12:12 AM
This is not so much a TV problem as a monitor problem, but I couldn't really think of any place better to ask, so here goes.

I have a Sony PVM-14M4U that I like to use for playing old video game systems that use composite video, S-Video, or RGB outputs. It has a great picture, and worked flawlessly when I purchased it a little over a year ago, but I noticed after I moved this past summer it started exhibiting an interference pattern in the video. It doesn't matter which video input is being used, which outlet the monitor is plugged into, or how isolated it is from other equipment; it always shows the same crawling diagonal line pattern over the image on screen. Same situation even here at my parents' house, where I brought it so I could mess with a computer that outputs a PAL signal while I'm home for Christmas break. At first I thought the interference was being passed along by the video source, but the interference doesn't appear on any of my 'normal' TVs, and like I said, I discovered afterwards that the same interference appears with any source.

All that being said, what might typically cause interference on a set that looks like crawling diagonal lines, and what might I look into doing to fix it? This thing has such a great picture otherwise that I don't think I can stand just leaving it be. Should I just start replacing capacitors, or what?

jmetal88
01-01-2014, 01:45 AM
Nobody? Even really generic advice would help me out. All I've done with this TV stuff so far is re-capping and replacing a few other parts in one tube set (although I now have two others lined up for whenever I have time). I mean, where would any of you start looking if one of your sets developed a problem like this with a direct (non-RF) video input?

jbattles
01-01-2014, 03:39 PM
post a picture so we can see it. 90% of troubleshooting is to see what's. its doing. you might need to do the solder grounds around the inputs if you lose a ground the signal goes crazy.

jmetal88
01-01-2014, 04:38 PM
post a picture so we can see it. 90% of troubleshooting is to see what's. its doing. you might need to do the solder grounds around the inputs if you lose a ground the signal goes crazy.

I can try to get a picture, but it's really faint, so I don't know if it will show up. It's just faint diagonal bands that crawl up towards the upper right corner of the screen, slow down, stop, reverse direction, and then crawl down toward the lower left corner of the screen. The lines themselves slope downward from left to right. I first noticed it on an S-Video source, but soon discovered it also affects the component video and RGB inputs. I haven't tried the regular composite video inputs yet to see if it affects them as well, but I'm fairly certain it would. The video, otherwise, has excellent color and geometry.

EDIT: Well, the video has excellent geometry except for the upper and lower portions of the picture being slightly more stretched out than the middle of the picture, but that isn't even noticeable unless you're looking at a vertically scrolling static image, so I'm not too interested in trying to fix that issue.

jbattles
01-01-2014, 05:02 PM
you might have a bad cable, that would cause it to have interference. check the solder joints around the inputs, if you are getting interference then you have a bad ground pr a cable. I would try that, its hard to figure out without seeing it.

jmetal88
01-01-2014, 05:32 PM
you might have a bad cable, that would cause it to have interference. check the solder joints around the inputs, if you are getting interference then you have a bad ground pr a cable. I would try that, its hard to figure out without seeing it.

I'd guess a bad ground is more likely, since I see the same interference from multiple sources using multiple different cables.

It does look a lot like RF interference, but since I get it from multiple sources, using multiple different cables, and in multiple locations, it seems to me like it's either being caused by something inside the monitor or it's coming in on the power line somehow. A bad ground would make sense, though, so re-soldering on all the rear connectors might be a good first step.

Haven't gotten my camera out to try to get a picture yet, though.

jbattles
01-01-2014, 05:40 PM
I would try that first all inputs share the same ground. reheat them and we will go there.

ChrisW6ATV
01-02-2014, 01:07 AM
I agree with others that a picture of the problem would help to diagnose it. It does sound like a ground issue based on the descriptions so far. Maybe a shield near or around the flyback transformer or the CRT has come loose; something like that could happen if the monitor was physically jarred during a move.