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Discussion Starter #1
Hi,

The green grid on the set was out of convergence and the minimal research I did initially told me the only way to fix the problem was a convergence board repair.

I did a pretty good amount of research before attempting this repair (I do some minor component repair on old data terminals we use in our legacy software application) and felt it was within my abilities.

I ordered IC's & some resistors from Service Manuals (another site had this site listed as OK to use), but I ordered the STK392-120's (not the 160's I see recommended here).

The repair went fairly well, the greatest difficulty I had was removing the high voltage connections from the flyback. I did remove the board from the TV to do the repair. I found one resistor out of tolerance and replaced it along with the 2 IC's.

When I reinstalled initially I had forgotton one of the connections between boards (the second connector back) and the result was an immediate power down when turning on the set. I removed the board and checked the soldering work (found the replaced resistor needed to be resoldered) and re-installed this time making sure all connections were done.

Now the power stays on, but there is no display. I am not sure what to check from here and any advice would be greatly appreciated. I have already had the recommended tech shop decline to help me since I tried the repair myself and now I am sick to my stomach that by trying to save some money I have destroyed the set.

Thanks in advance,

Ed
 

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Check all connections. Most likely just something that you forgot to plug in or a wire pulled loose on the other end.
 
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Discussion Starter #3
Thanks for the quick reply!

I did read that in other posts and checked as best I could on the board itself before posting my first message.

The only notable thing on the board is that one of the high voltage wires from the flybacks seems to have more upward play than the others. Would one flaky wire affect all 3 crt's?

When you say "the other end" do you have any likely suspects to check? It seems most of the wires are bundled up in wraps along the top of the rear access area and then disappear to each of the lenses/crt assemblies behind them. So my initial take is that it would be very hard to have yanked out any of the comms or power cables.

I will check again when I get home tonight,

Ed
 

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If there is any play in the anode leads STOP! If you have a bad connection inside the flyback you will end up burning the connections and have to replace the transformer. If you can't get it to catch, bend the "wings" out slightly at the end of the lead before pushing it in. Only slightly.

Look for a wire unplugged on one of the CRT boards.
 
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Discussion Starter #5
The one "loose" wire catches (you cannot pull it out), but it does not seem to be as tight (they all move a little) as the others. I will check that carefully when I get home.

When you say the transformer, you mean the flyback, correct?

If I have fried it, would there have been any noise or smell associated with that type of failure as it happened? I do not remember any event like that when I first turned it on. The CRT's have never fired up at all.

I'll post again this evening.

Thanks again,

Ed
 
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Discussion Starter #6
I checked the connections I could see (I pulled the front panel to get a better look at the CRT's) and I could not find anything unplugged. I checked the leads from the flyback and they all seemed OK as well (my earlier impression that one was loose was not correct - the only time I could get any play was when I pushed down and all 3 did that).

The only thing that might have something to do with it is one green LED at the front right (looking from the back) of the middle board is not lit. I do hear any noises coming from the flyback. It's like no power is getting to the board.

I had to run my son's hockey practice tonight, so I did not have much time to look things over beyond the connections, but I will remove the board tomorrow and see if I can see any problems with the circuit board.

Would it be a solution to just buy a replacement convergence board? I know they are expensive, but I am not sure what else to look at.

I usually am pretty successful at various tasks, ranging from R&Ring the suspension on my car to plumbing work to 110 electrical work, but maybe I stretched it too far with this job?

Ed
 

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If you have an LED not lit, that is an indication of where the problem might be. These should all be lit and if they are not it indicates one of the supply lines is down.
 
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Discussion Starter #8
Got it. Do you know where I can get a service manual for this unit?

Ed
 
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