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29" Makvision monitor shutdown and leaking capacitors?

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grantspain:
so your tech should read all the high voltage caps in the horizontal deflection circuit, the HOT and check any fet's if fitted on this chassis
pretty sure this is a rebranded weiya 2929 monitor

mamenewb100:
Just wanted to update on this and ask a few questions. I finally got around to looking at the monitor again. After finding out someone local  will not work on my monitor, I decided to take it upon myself to learn and try to repair it myself. Even if I end up dumping money, not fixing the problem, or (hopefully not) damaging something. It will totally be worth it for the learning experience. I had a little experience practicing with soldering/desoldering on test PCBs and doing some basic mods on other electronic devices. I have a multimeter, soldering station with iron, desoldering pump, solder, flux, wick, and all sorts of other tools neccesary for most repairs. Also have a capacitor replacement kit for replacing the old caps if necessary.

I have the main PCB and Neckboard chassis removed for work. The board seems relatively clean with no obvious burn marks or bulging capacitors. I removed one of the larger capacitors that looked like it could be suspect but it has the same ESR readings as a new capacitor, so it was likely fine. I DID however notice that there was a good amount of corrosion around the main fuse after I pulled it (Check the Picture). The fuse also had poor continuity in comparison to a new set of fuses that I ordered. Which I would think could cause some bad problems. Am I wrong thinking this could cause voltage fluctuations with a bad connection to the fuse? I noticed the picture on the tube would also wobble noticeably from even the slightest vibrations or touch. Which many say could be a connection problem or cold soldering joints. Also curious if it's normal for the neckboard to remove from the tube very easily? Felt like it was barely connected with no click or snap.

I also did find a small crack in the Flyback Transformer after removing some dust from the body. This may not confirm the Flyback is bad but based on the problems I've had, I don't know what else could have caused the sudden loss of picture. Also removed and tested what I believe to be the HOT. A transistor near the FBT. I'd read that it should be around 40 to 60 Ohms reading from the Emitter and the Collector. But I'm only getting about .7 Ohms which I would assume to be shorted. I could measure B+ and other areas in the power supply but as of yet I'm not sure how to safely do that. As I'd assume you would need mains power for that?

Biggest problem I have right now is finding a Flyback. Found out that the HI-2929D-01 I need to replace is hard to find. Only one guy on Ebay was selling new old stock of them but they are currently out of stock and won't be available for another 6+ months. Interestingly there is another number listed on the Flyback that reads 'MTI-LTC-031'. If you do a search it comes up with a HI-3129C Flyback that shares the same number and IS in stock right now. I'm wondering if anyone would know how to check if it's compatible with a HI-2929D? It does have the same looking pin pattern like it would solder in to the CB. But of course the voltages could be different. I've tried searching for answers on compatibility but any info on Makvision Wei-Yas seems very scarce.

So to keep things as short and concise as possible.. My rookie analysis of the problem without any in-depth measurements of voltages so far is that the Flyback is likely bad, fuse needs to be replaced, the HOT needs to be replaced along with possibly other transistors near the FBT, replacing old capacitors, and reflowing the board with fresh new solder. I feel at the very least this would get me power back to the tube unless I end up finding out the tube is bad. Which I don't think it is. Does this seem like a good direction to go in? I'd liked to hear other experienced opinions on what may be the best route to go or what may be a waste of time and unnecessary/risky. Appreciate any help or input as I know trouble shooting electronics can be a pain in the --I'm attempting to get by the auto-censor and should be beaten after I re-read the rules--. Especially without physically being able to work on it. Provided some photos.

lilshawn:
i would go ahead and replace that flyback. it is most assuredly toasted with it looking like that.

as for the 2929 VS 3125, they are BASICALLY a similar monitor with a few differences... might be a dual focus vs single focus leads. in which case you can cut off the second lead at the flyback and throw some shrink tube over the nub. they are both the same size monitor so they should be pretty close.

if it' where me, I'd swap it with a 3125 if that's all I could get. if you don't mind waiting, wait for the proper part. (I'm a jerry rigger at work and we do what it takes to get games working)

you are going to want to go ahead and change out the HOT too as well. it might work now, but who knows how long it will last if it's had to drive that flyback.

Zebidee:
I notice there is no metal shield / heat sinks around the flyback/HOT and a couple of other big transistors, even though there are holes in the chassis to screw them in. Can't be good  :-\

mamenewb100:

--- Quote from: Zebidee on February 07, 2022, 08:30:09 pm ---I notice there is no metal shield / heat sinks around the flyback/HOT and a couple of other big transistors, even though there are holes in the chassis to screw them in. Can't be good  :-\

--- End quote ---

I removed the heat shields because changing out transistors and the flyback would be difficult with them left on. Definitely were on when the monitor was in use.  :)

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