Riddled TV Repair Forum

gpriore · Joined: 07 May 2007 Posts: 6

Hello! I'll get right to the point. There is often a repetitive and rhythmic type of interference in the TV's performance, regardless of what channel is selected. And nothing is ever completely clear. Even if you use it to watch a DVD disc, there is constantly rough lines moving across the screen. I know for SURE that it is neither Radio Frequency or Electro-Magnetic Interferences because, I have a Toshiba TV which is even older than this Sylvania, and when I use it in the exact same location while being plugged into the exact same outlet, it operates in a 100% flawless manner; and everything, regardless of which channel is selected, is crystal clear. I contacted a local TV technician who personally looked at
the TV, and he explained that it needs a new 'Fly Filter'. However, he gave no other details whatsoever, and also stated that these types of parts are no longer available. Who knows if he even knew what he was talking about ANYWAY. I would be most sincerely grateful if someone would be willing to kindly offer any kind of advice. --Thank you VERY much for your time!!!
--Gabe

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kuhurdler · Joined: 28 Dec 2006 Posts: 2582 Location: Overland Park, KS

I'd guess your repair guy was referring to a capacitor. But I'm not certain. I'd check the large electrolytic capacitors in that TV first. Starting with the largest one near the main rectifier.

gpriore · Joined: 07 May 2007 Posts: 6

Dear kuhurdler. Thank you VERY much for your response!! I originally wanted to state that I feel massively priviledged to have found this website and, after reading many of the posts on this forum, I am absolutely amazed at the kindness and generosity of your heart, for being willing to voluntarily offer such a wealth of advice. I have already felt as if my IQ has increased tremendously. I am also astonished that there are so many people that are not even considerate enough to reply to you and others with a 'Thank You'.

OK. May I kindly ask where exactly the main rectifier would be located? Would there happen to be a picture somewhere on the internet that would show what the main rectifier of the inside of a TV would look like? Also, how would you recommend checking the electrolytic capacitors? What type of action should I put forth in order to check them? One other question. I read your post regarding the Discharge Process. If a TV has been unplugged for at least 24 hours, would discharging it still be necessary?
--Thank you VERY much for all your time and knowledge!!
--Take very good care.
--Your friend, Gabe

kuhurdler · Joined: 28 Dec 2006 Posts: 2582 Location: Overland Park, KS

Thanks,
I do what I can. The main rectifier is usually very close to where the AC power cord is attached to the circuit board. It either looks like a bridge rectifier http://en.wikipedia.org/wiki/Diode_bridge or it can be 4 seperate diodes.

To check electrolytic capacitors, the easiest way is to find the one with a bulging top, or the one that has ooze coming out of it. But that doesn't always happen, and sometimes they just go bad enough to be out of tolerances.

In that case, you can use a device called an ESR meter.
here is a good article on capacitor testing: http://www.repairfaq.org/sam/captest.htm
here is the ESR tester I bought, I assembled the "kit": http://www.flippers.com/esrktmtr.html

Most likely it would not be necessary to discharge your CRT... but do it anyway! Because it's super easy, AND IT COULD KILL YOU.

If you take a picture of the TV, I could tell you what I think the main filter capacitor is.

gpriore · Joined: 07 May 2007 Posts: 6

Dear kuhurdler, Hello! The information you provided was just absolutely spectacular! I read the articles for a couple of hours, and truly ended up feeling like a real technician, with the exception of my newly developed fear, regarding the CRT discharging process!

I took a bunch of pictures of the TV, and have posted a total of 29 photos. You were definitely right! The largest capacitor {which is pictured in photos 1-8} is the only capacitor that appeared to not be perfectly flat at the top. It literally looks as if there is internal pressure, making the top appear slightly buldged. However, every other capacitor, as you'll see in the other pictures, look completely perfect; all the tops look totally flat. In pictures 10, 13, 14, 20, 21, 22, and 25, you'll noticed screws on what appears to be a plastic frame. I wanted to ask you about these. I assumed that if I remove these screws, then the circuit board will be removable, however, with only one noticeable obstacle. The large rectangular metal device that you see in pictures 22 and 23, is connected directly to the coaxial ANT/CABLE connector which is surrounded by a large metal frame that you see in picture 17. In picture 19, that large metal frame is connected with a screw to a different device which holds a circuit board. Would you know how to disconnect the large rectangular metal device that is connected to the ANT/CABLE connector? In picture 18, on the bottom left-hand corner of the large metal frame, you'll see a small metal clip which goes right down to the wooden board. Is THIS an example of what I could use as a 'ground' for the CRT discharging process?? I was SERIOUSLY frightened after reading the article about the discharging process. Since I honestly could not figure out what I could use as a 'ground', I was worried about being killed!!

Alright. I'd like to thank you VERY much again for your great kindness!!
--Take very good care.
--Your friend,
--Gabe

http://technicalphotolistingsite.com/default.aspx

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kuhurdler · Joined: 28 Dec 2006 Posts: 2582 Location: Overland Park, KS

alright, the large rectangular metal thing you asked about is the tuner, and it is grounded. And you should leave it attached to the circuit board... it is soldered. You should be able to remove it from the plastic piece that it goes through on the back (the part you plug the cable onto). There is probably a hexagon shaped nut on the outside that you may need to unscrew.

by the way, most of the heat sinks are grounded too, and there is probably a metal bracket holding in the CRTs that is grounded as well.

This probably goes without saying at this point, but make sure the TV is unplugged when you have it open.

gpriore · Joined: 07 May 2007 Posts: 6

Dear kuhurdler, thank you VERY much for that info! May I ask if you thought the pictures were good enough? Or, would you recommend that I take additional pictures? Based on the pictures you saw, would you be able to figure out a good example of what I could use as a 'ground' for discharging the CRT?

Would you know of where I could purchase a new capacitor, such as that exact same large capacitor that was buldging? And how should I identify the right capacitor to purchase?

--Thank you so much for all your time!!
--Your friend,
--Gabe

kuhurdler · Joined: 28 Dec 2006 Posts: 2582 Location: Overland Park, KS

the pictures were fine,
Maybe a wide picture of the entire board would have helped. But they worked fine.

Here is one place you can buy it:
http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?Ref=24063&Row=215054&Site=US
There are other places too
You're looking for a 330uF capacitor (thats pronounced 330 Micro-Farads) with at least 250V (Volts) rating