Bouncing screen (composite/S-video) on Trinitron; component works great

I got a KV-36XBR450 off Craigslist (free). Got it home and plugged in a Wii with component cables; worked great.

Tried both a PS1 and N64 in all of the composite inputs. I get a signal, but it bounces around on the PS1 and scrolls constantly on the N64.
I was able to dig up a Nintendo S-video cable. It does the same thing as composite.

The weird thing is, picture looks just fine when I pop a VHS tape in and play it (through composite). No scrolling video. Back at the VCR menu though, the screen scrolls.

Also, I hooked up an OTA converter. So, my OTA antenna feeds to the converter, which takes coax to the TV for OTA channels. Doing this, the picture still bounces some. It's watchable, but annoying.

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I'm mostly just curious if anyone else has ever had/fixed this problem on a Trinitron before? My guess is it's some capacitors or something that need replaced. I don't think I will open a CRT (shock danger), but, I'd like to know what the fix is if there's ever a chance I can get someone to repair the TV.

 

Hey there,
interesting problem. I've worked on a lot of CRTs over the years (used to work in an arcade repairing them) and I've not seen something quite like this before. It sounds like your CRT hates inferior systems....try plugging in a Genesis and see what happens! (jk )

Actually, your chroma decoder circuit appears to be the problem. There is a set of ICs that decode the incoming video signals and if you're lucky you will have 2: one for component and one that handles composite / s video. The later is obviously having trouble with the sync. This is usually going to be an issue solved by replacing capacitors around the chip.

Working on TVs is not as dangerous as you would think. Just don't unplug or touch the giant anode cap that goes to the tube and wear thick gloves. I be the encoder circuits are on a daughter board anyway, often you are able to unplug it and take it out to work on.

-Segasonicfan

 

Yes it is - especially to someone with zero knowledge of electronic engineering.

JUST?! Don't touch the LOPT, either. Or any of the HT circuitry. You know.... the stuff that has tens of thousands of volts going through it. And don't hit or drop the tube or it may implode, then send glass fragments at you. And, of course, the chassis is live on this set so an engineer would use an isolation transformer.

What the?! Don't do that - you're not going to be able to service it wearing them! The only time you MIGHT wear gloves is when handling the tube.

If you don't know how to service a TV, take it to a good old-fashioned television repair shop.

Scrolling, though - try tweaking the vertical or horizontal hold, depending which way it scrolls. Are the consoles from the same region and running at the right speed? Check the signal levels of the outputs (including anything that's working correctly).

 

You could reset the settings and/or attempt to tweak them. Take a look at this - http://www.neo-geo.com/forums/showt...ice-menu-Tips-Tricks-and-settings-suggestions

 

All consoles are US region, as is the TV. I'll maybe snag a video of the problem. It's more bouncing than scrolling I guess.

I have already tried a factory reset, to no avail.

 

Most modern TVs often have bleeder resistors for the high voltage sections. Anyway, I'm not sure why you would recommend against wearing gloves (or a glove) when working on / handling a CRT. This is standard practice prior to discharge and is the primary way to avoid shocking yourself. Also take off any jewelry or watches you may be wearing (conductive metals).

You can easily probe with a multimeter wearing gloves. I can remove capacitors and do all sorts of work wearing a glove. There's nothing wrong with doing that. But yes, watch out around the Flyback and other high voltage sections of the board. Anyway, the chroma encoder is usually on a sub board away from all that (low voltage section).

If you can afford it, take it to a repair shop. And check out some safety guides on working with CRTs online. It's also smart to not be alone in your house / shop when doing that work, just in case something happens.

-Segasonicfan

 

Sorry, you're just showing your ignorance. That doesn't protect you if you touch a live part carrying tens of thousands of volts. You need to work on a live chassis to fault find.

Bullshit. I'm qualified as a television engineer, work as a professional arcade technician and nobody does that. You don't wear thick gloves because you don't need to... and how the hell are you going to adjust controls on a LOPT or use a multimeter probe with thick gloves? It's impractical. The only time I ever wear gloves is when I need to use hot air... and I prefer not to whenever possible as they make things awkward. They're only strictly necessary if you use dangerous chemicals (again, I'll use the right gloves for the job). Whilst you can get HT gloves (class 4), they're ridiculous and not practical for use in television sets. Anyone using gloves is most likely NOT using gloves that will actually protect them against 20-40 kV in the HT circuit. As I said, a competent engineer would use an isolation transformer... and common sense.

Go and watch Randy Fromm's monitor repair school videos. Notice the lack of gloves. Google discharge CRT. Note how you see lots of bare hands... the one picture that has gloves is the Instructables page, and they're pathetic gloves that won't help much.

The only time you need gloves, as I said, is when handling a CRT. Goggles, too. That's in case you drop it and glass flies in your direction. You can also find a CRT has become damaged (e.g. neck broken) and you'd need gloves to prevent cutting yourself.

IF anyone is going to work on a CRT, then I strongly suggest having a strong knowledge of electronics theory and the correct safety measures for handling one. If you have any doubts, take it to a qualified repair technician. Clearly, we need a disclaimer:

Any advice given by on ASSEMblergames.com regarding working on electronic circuits, especially those that are connected to a mains supply, is the opinion of the individual. It is up to the reader to ascertain whether it is advice they should follow and/or seek a second opinion. Anyone following such advice does so entirely at their own risk. ASSEMblergames.com accepts no responsibility for any damage or injuries that result from taking the advice of third parties posted on the forums.

 

Video is up showing the problem.

 

why are you twisting my words about this? Of course bleeder resistors won't help with a LIVE circuit. and you do not always need to work on a live chassis to fault find. As I said, I worked as a technician in an arcade (and I've been in the business for some 12 years) and I've fixed plenty of chassis that were completely shut off on my bench.

Again, I recommended gloves as an extra safety measure for a newbie. There is nothing wrong with it. At worst, it is as you say, "impractical." It's not going to hurt the guy to wear gloves working on a chassis. but w/e we're just beating a dead horse here.

Thanks for the video. Your problem appears to be with the V HOLD circuitry. I think a recap would most likely fix it.

 

I'm not. You said, and I quote:

"Working on TVs is not as dangerous as you would think."

WORKING on televisions does NOT mean simply discharging them. It means... working on them. To do that, you need to have them running. Hence a bleeder resistor is not going to help you if you stick your hand in the back when it is on and you're working on it.

I never said you ALWAYS have to work on a live chassis, but you will quite often be doing so. Proper fault finding relies on elimination, rather than just changing caps for the hell of it, which oft seems the go-to with console "repairers" these days. Not that an issue can't often be fixed by caps (in consoles and all sorts of equipment alike), of course... but it's no substitute for proper fault finding. A vertical hold issue, for example, is likely fixable by changing just a couple of capacitors. Not that it would hurt to totally recap, but it's gonna be tedious and more expensive. In later televisions, an EPROM could go bad to cause hold issues, too.

The wrong gloves aren't a safety measure at all, so it is not good advice. You said "thick gloves". What, gardening gloves? That's gonna do a lot! Class 4 HT gloves or it's unlikely to protect you from a shock.