Vintage 4.5" CRT emits cracking noise, I'd love to fix it

This might sound funny, but I'd like to repair a vintage 4.5 inches black and white small CRT tv. I got it yesterday from it's original owner, I tested it during the transaction, but didn't detect the defect before I was home.

The symptoms are :

  • The flyback transformer emits long sequences of cracking sound (1 or 2 minutes), like if it was internally arcing. Each sequence is isolated by no cracking at all. There's no visible arc, I turned all lights off and I assert, no arc is visible.
  • I can't detect any ozone or burning odor.
  • When there's a signal on the UHF port, the image is not filling the screen, it's vertically compressed.
  • The image is blury, and when the transformer emits a sound, the beam does a "kind of" vertical sinus line wave starting at the top of the screen, and ending at 1/3 from the top. (Probably the duration of the discharge)
  • The sound is correct and everything else is working properly.

I'd love to meet someone who knows how to fix these TVs. Of course I know they are probably rare now. I have no expectations, but it would be sad, the object is pretty, I mean, the design of it is vintage and looks great for its time, such a nice object isn't allowed to be trashed away. Thus, the cost of fixing it isn't a concern to me.

I'd like to know :

  • Can it be fixed in 2017?
  • What problem is it likely to be?
  • Is there a reference/guide on repairing such devices, I found informations on youtube and some website, but I'm not enough knowledgeable in electronic to debug this without help using these.
  • If I can't fix it myself, who could do it for me?

Edit :

@oldturkey03 found :

TV was marketed in the USA as a Cosmo 4.5" Portable Mini Personal Television TV-600-05. Cosmo Communication out of Miami Fl was an importer of "inexpensive" electronics made in the ROK.

Thank you!

Some photos :

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Contestado! View the answer Yo también tengo este problema

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Btw, I know how to solder, how to use a multimeter and I understand the basics of electronics.


@modernbison and just to make sure you do know that CRT's carry enough power to zap you extremely hard! Just making sure while we are trying to figure this out:-)


Thank you for the warning. I'm very cautious about it.


Okay going by your description and the pictures I'd be looking at the vertical deflection IC's and caps. Let's see if we find a schematic for the board.

In the meantime it looks like you have about 3 or 4 IC's on your board. Any chance you can tell us the manufacturers numbers labels etc. on those?


How do you find a schematic for a white labeled product?


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Looks like a fun project and you did right to ask @oldturkey03 for help. When I used to work on these the main issue that repaired many were just simple cold solder joints. I'd go over the board with some good silver solder and a solder gun and see if your issues are resolved.

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Yeah! Sure, I'm learning how these tv worked and how to debug electronic problems. I learned electronic theory, but never played on a real board. It's pretty interresting.

Pending the arrival of the ESR tester, I will secure the joints. As @oldturkey03 and @pleriche suggested that vertical deflection circuit seems to be the culprit, I'll secure the solder joint from there.

Very helpful, thank you!


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Emmanuel estará eternamente agradecido.
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