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JTS1957



Joined: 21 Jan 2009
Posts: 2394
Location: Far, Far Away

PostPosted: Sat Dec 18, 2010 1:15 am    Post subject: Reply with quote

Feel heat sink that horizontal output transistor is secured to (Q404 right behind flyback transformer). Only run set short time.
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sdtv



Joined: 31 Mar 2008
Posts: 12

PostPosted: Sat Dec 18, 2010 8:01 am    Post subject: Reply with quote

Unplug the tv, discharge the filter caps so you don't get shocked and feel for what is getting hot.

Most likely something is shorted or you got solder on something you should not have and caused a short.
1968RT



Joined: 13 Mar 2010
Posts: 51
Location: michigan

PostPosted: Sat Dec 18, 2010 2:45 pm    Post subject: Reply with quote

I think Q404 is the component making the smell. I haven't left the set on for more than a minute, but in that short of a time the heatsink is warm.
I don't seem to smell or feel any other component getting hot.
sdtv



Joined: 31 Mar 2008
Posts: 12

PostPosted: Sat Dec 18, 2010 7:09 pm    Post subject: Reply with quote

Is it shorted ?
JTS1957



Joined: 21 Jan 2009
Posts: 2394
Location: Far, Far Away

PostPosted: Sat Dec 18, 2010 7:46 pm    Post subject: Reply with quote

I don't object to the "free" flow of information. I DO object when everybody and their brother is trying to make a dollar. (The cost today is just $37.00.)

Just Google "Testing ______". Just type in the name of the component. Read a few and be your own judge as to which one to use. (You may not have a curve tracer, but you may have a DVM). And it is FREE!


Possible bad flyback transformer (23236259 / TFB4100AD) if transistor is shorted try replacing it first. Also check C416 (10ufd 100V) electrolytic. Transistor (2SD1428) should run approx. $10 - $15 to your door.
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sdtv



Joined: 31 Mar 2008
Posts: 12

PostPosted: Sat Dec 18, 2010 8:03 pm    Post subject: Reply with quote

That book costs about the same as 2 or 3 transistors. :D
1968RT



Joined: 13 Mar 2010
Posts: 51
Location: michigan

PostPosted: Sat Dec 18, 2010 11:45 pm    Post subject: Reply with quote

OK gentlemen I have arrived back at square one. Q404 was shorted. I took a SD1427 out of another junk TV and replaced it. Q404 was a SD1428, but I cross referenced it and they are interchangeable. I have the original 3 inch high picture with sound. Since I replaced those caps and the vertical IC301, Can you tell me what other components I should test, and if they can be tested in circuit. I am currently only armed with a digital multi-meter. Again I appreciate your time and patience. Thanx
JTS1957



Joined: 21 Jan 2009
Posts: 2394
Location: Far, Far Away

PostPosted: Sun Dec 19, 2010 5:17 am    Post subject: Reply with quote

Other than IC501, all that's left is discrete resistors, capacitors, diodes, etc.
1968RT



Joined: 13 Mar 2010
Posts: 51
Location: michigan

PostPosted: Sun Dec 19, 2010 6:11 am    Post subject: Reply with quote

GOT IT!!!!!!!!! I was looking at the board very closely for trace cracks, burns, bulging caps and the like when I noticed that C342 had dust on it.
Now obviously the whole board is dusty, but this cap was dirtier than the surrounding components. When I dusted it off it looked like it was wet. I pulled it off the PCB and sure enough the bottom bung looked melted. Replaced it and VOILA full screen! During some slight bumping I noticed a momentary picture outage. I found a cold solder joint on Q820 and that seems to have solved that problem. Picture looks good. Even though the set is 18 years old, my friend says his mother in law didn't put much mileage on it. Thanks again guys, I couldn't have done it without your expertise.
JTS1957



Joined: 21 Jan 2009
Posts: 2394
Location: Far, Far Away

PostPosted: Sun Dec 19, 2010 6:28 am    Post subject: Reply with quote

You're welcome. Enjoy the set.
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