OH NO! Blue Flickering with Sony PVM 14M4U

[MadMagikarp5050]

I bought the monitor off of eBay and it was working fine for roughly 3 months or so, maybe a little longer. Now there is a blue flicker that intermittently occurs. The blue emissions will normally stay at low variances, almost pulsating in a way, and then occasionally spike with intense blue and fade back to normal. The behavior is unpredictable.

I have already tried:

*Both having the TV plugged in with different consoles and nothing plugged in at all
*Changing the cables (power and A/V, not the TV's internal cables)
*Changing the input source
*Changing the various settings on the tube
*Moving the tube to different locations
*Turning off the air conditioner (interference)
*Plugging it in different sockets, including with and without the surge protector
*Giving it a light tap on the side

Nothing works. Dammit....


Video:
https://www.youtube.com/watch?v=HkHhEM0Cjtg

My phone's camera has issues trying to pick up some of the problem, but there are several moments where it is blatantly present:

0:29-0:36
1:50-2:25 (after turning on Blue-Only mode)

Anyone have an idea what it may be and how I can fix it?

Thanks!

[MadMagikarp5050]

I should probably mention one more thing, there is a high pitched sound that comes from the T.V.

If I remember correctly, this means that the sealant on the flyback is loose. I also read that this could just be normal behavior.

Also, I apologize for leaving out editing in the video; I didn't want to waste too much time converting the video to a format my video editors would be able to work with, so I just uploaded the whole uncut video. Otherwise, the problem mainly persists in the times listed above.

[MadMagikarp5050]

Bump

[MadMagikarp5050]

Bump numba 2

[MadMagikarp5050]

Bump


Is this an obscure topic? Is it a noobish question? I typed in all sorts of keyword combinations into both Google and DuckDuckGo and can't find decent information on a proper fix besides rejuvenation. Any help would be appreciated.

[Dave_K.]

Most likely needs to be recapped. Sorry, probably not an easy thing to do on a broadcast set like that.

[zionfarm]

Did you ever get the problem fixed on your PVM?

[MadMagikarp5050]

Hello again!

No, I haven't fixed the problem yet. I am currently reading a book on electronics to make sure I don't kill myself before attempting to recap the set. Another troubling issue is that I can't find a good scan of the service manual for this particular set (the circuit diagram is too low of a resolution). I also tried to find the manual on ebay but no dice. On top of that (the problems just don't stop), I can't find a handy dandy capkit, making this job even more difficult for a novice such as myself.

Woe is me

[MadMagikarp5050]

Do any of you veterans have some advice before I decide to open this beast up? E.g. What to watch out for, best practices, what to read, etc.?

Thanks!

[soviet conscript]

I'm having a problem very similar to yours. I get a blue color shift that comes and goes. sometimes I can play for a few hours before it happens and sometimes 10 minutes. once it happens it tends to stay for a good while before shifting back.

I'm pretty bummed about it.

[MadMagikarp5050]

Its kind of unfortunate there hasn't been much info shared by other wiser members of this forum on recapping a PVM, even though I'm sure most have.

I understand there are some questions that seem simple enough to google from an enthusiast's standpoint, but sometimes great information can be shared to new hobbyists that cannot be obtained from an article or a youtube video.

For example, I am a Linux enthusiast with a vast amount of knowledge regarding the linux binaries and C language but I still give beginning users advice, knowing that it may benefit them if I point them in the right direction.

[kamiboy]

Try not to die due to a high voltage shock is a sound advice to start off with.

Google CRT discharge. Few "experts" here have had any experience with actually pulling out the innards of a CRT and having a go at it, thus there is not much to say.

[Unseen]

Do any of you veterans have some advice before I decide to open this beast up? E.g. What to watch out for, best practices, what to read, etc.?

Reading at least the safety advice in the Repair-FAQ about Television sets is a good idea.

[kel]

Turn it off, unplug it an just open it up and have a look around. There's nothing like first hand experience.

Take some time to familiarise yourself with the inside of the set like where the mounting screws are, wiring harnesses ect.

You should be fine if you pay attention to where you are sticking your fingers. Obviously don't go sticking your finger under the Anode cap on the CRT and avoid touching any terminals on the underside of any boards with high voltage caps on. The main one to avoid is the main filter cap in the power supply (the biggest one in the set) the other high voltage ones could probably give you a bit of a sting but nothing to write home about. I've had mine in bits a few times and not once have I actually needed to discharge the CRT or any caps although I still did it as a precaution every time anyway but only if I was actually stripping it down fully other wise I would just be mindful of where I was sticking my fingers. I think that the PVMs discharge the CRT and caps once you turn them off anyway but don't take my word for it, always manually discharge as a precaution if you need to go that far into the set but for now you are just familairising yourself with the insides so don't worry too much.

Be very careful not to accidentally knock the neck board whilst looking around. They stick out like a sore thumb and if you accidentally hit it with enough force then you could potentially break the neck of the CRT and then the set will be a giant paper weight.

Once you have familiarised yourself with the mounting screw locations and wiring harnesses you should be able to undo a few and very carefully slide the G board out (The main and largest board in the set) just enough to see all the caps at the front. After that visually check all the electrolytic caps in the set and particularly the power supply area for signs of bulging or leakage but don't expect it to be that easy, you will be lucky if it is.

Before moving on make sure to check that the CRT is fully discharged. There are plenty of guides on Youtube showing how to do this

After making sure that the CRT is discharged just pinch the top of the anode cap together and gently pull it away from the CRT.

I you don't see any bulging or leaking caps then the next step would be to strip the whole set down and visually check the boards for loose, dry solder joints. Just stripping the set down can be quite a job in itself if it is the first time you've done this and once you get those boards out now would be a good time the make sure that any high voltage caps are discharged with a high wattage resistor.

You will probably need to take the neck board off. The plastic clip holding the neck board in place can become very brittle over time and there is a chance that it will just break into pieces with the slightest attempt to move it. If you find that you have to remove the neck board then don't use the jubilee clip to remove it, try to unclip the 3 parts from the neck board itself instead. Then very, very gently wiggle the neck board away from the neck of the CRT.

Once the neck board is off you should be able to unplug and remove everything from the set.

If you can't see any bulging or leaking caps or any loose/dry solder joints then it's probably time to consider wether repair or replace the whole set to be honest. From here on without any real experience in TV repairs you will probably end up spending a lot of time money and effort in finding the fault so unless you enjoy doing it for the hell of it or just learning by trial and error you may end up out of pocket and very disappointed by the end of it all.

At this stage you could either buy and ESR meter and try testing all the caps in situ and hope that you can find the bad one or two that need replacing or spend a lot of time and money recapping the whole set. At the very least a full set of decent caps for a set like that would be around $60/£40 or more and the time and work involved in replacing them may not be worth it considering at the end it may not even fix the original problem or even worse could even introduce new problems. If you enjoy learning by trial and error and are not put off with possibility of loosing time and money with nothing to show for it or even worse results at the end then I say go for it but other than that save yourself the stress and seriously consider replacing the set.

Disclaimer: I am not a qualified TV repair technician. All my advice is from personal experience gained from internet sources and trial and error. Follow any of my advice at your own risk.

[MadMagikarp5050]

Thank you everyone for the advice! I will take a look at the manual posted and research Kel's advice to better familiarize myself with the TV. The TV has been unplugged for roughly 3 months now but I probably wont open it till I have most things in place.

In order not to buy low grade caps, where is a reputable online shop that sells reliable capacitors for this kind of job? Also, where can I buy a service manual (or location of a high-res scan) for this set? I may end up contacting Sony themselves but I have a feeling they will charge an arm and a leg for a product that isn't sold anymore.

Thanks again everyone! I will make sure to document my progress for anyone else who comes across similar issues, such as Soviet Conscript.

*edit*

Doing a quick google search for caps points me to Digikey, as well as Badcaps.net for references.

[kamiboy]

As for caps, Nichicon and Rubycon are good high quality brands. Try to get 105 degree ones as they will last longer.

[Skips]

MOST Sony PVM's actually discharge their CRT completely upon power down. Even the PVM-1271Q from the late 80's I had did this. Out of all the models of PVM I have had I have not come across one that does not do this yet. That doesn't mean ALL models do this, just a very large number of them that I can see from my experience. Although it is a safety precaution to discharge them anyway to make sure, once powered off the Sony PVM monitors are actually very safe to work with. The things that don't auto discharge are the various capacitors on the circuit boards themselves. You may still get a painful shock (but nothing life threatening) if you touch the bottom of the circuit board without watching what you are doing. I think the worst shock I even got from the capacitors themselves was a small burn on my thumb when a larger capacitor shocked me. I was careless and touched the bottom of the PCB with my hand after it had been removed from the monitor.

I have opened up the 14M4U to replace those few faulty/incorrect caps Sony had on the A board. When I powered off the monitor the 14M4U fully discharged on its own, no manual discharge of the CRT was needed. I was able to simply remove the anode and go to work. I really would not worry too much about causing great bodily injury while working inside a 14M4U, its a pretty safe monitor when not turned on. Just make sure its unplugged before you do anything with it and you should be fine if just recapping it.

Models that I have had (and actually opened) that have auto discharged their tubes on power off are.

Sony PVM-1271Q
Sony PVM-1371Q
Sony PVM-1343MD
Sony PVM-1943MD
Sony PVM-1354Q
Sony PVM-1954Q
Sony PVM-142MU
Sony PVM-202MU
Sony PVM-14M4U
Sony PVM-20M4U
Sony PVM-14L2
Sony PVM-20L2
Sony PVM-14L5
Sony PVM-20L5

Most medical models are not listed. I have had them but they also discharged their tubes. I have only listed the medical models that I have not seen the non medical versions of in person.

[Balzac]

Skips, did you ever figure out what the issue was? I'm experiencing a similar problem on my PVM-14M2U but with a red flicker that intermittently occurs.