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 :
Es esta una buena pregunta?
16 comentarios
Btw, I know how to solder, how to use a multimeter and I understand the basics of electronics.
- de Emmanuel
@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:-)
- de oldturkey03
Thank you for the warning. I'm very cautious about it.
- de Emmanuel
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?
- de oldturkey03
How do you find a schematic for a white labeled product?
- de Emmanuel
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