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#1
03-27-2009, 11:06 AM
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Two Sharp TV's. No picture on either.
I found two Sharp TV's that have no picture. One is a 32 inch 32R-S480 made in 2001, and the other is a 25 inch 25K-S100 made in 1998. Here are pictures of the tags on the back of both sets.
  The 32 inch powers up to the point where I can hear the degaussing circuit. I do not hear the CRT scanning. Bad HOT maybe? The 25 inch one is more interesting. It powers up, I can hear the CRT scanning, and there's even sound. But no picture. I thought I could play with the flyback to get retrace lines, but no go. Nothing on the screen. Yet I'm sure it's drawing a raster, because I can hear it. EDIT: disregard the 32 inch Sharp TV. The CRT is broken at the neck. Last edited by MRX37; 03-27-2009 at 01:29 PM. 
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#2
03-27-2009, 11:16 AM
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Can you tell if the CRT filament is lit in the 25" one? I've seen that problem many times in TV's over the years.
That 32" set could have any number of problems. You might get lucky and it only be loose connections.
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#3
03-27-2009, 11:51 AM
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Quote:
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#5
03-27-2009, 01:33 PM
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It seems like we're both having the same bad luck with TV's lately. With me, it's always the nice, big sets that I could get some decent $ for that end up costing too much to fix or they are a dog to fix. Let me bring home some mid '80's goldstar with 30 cigarette burns on the case and I'll have it fixed in ten minutes out of my junk. Of course, no one wants something like that because it's NOT MODERN ENOUGH LOOKING!
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#6
03-27-2009, 02:10 PM
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Yeah. Well, the 25 inch one I can get a bit of cash for, if I can figure out why the CRT element isn't lighting. You said you've seen this problem before... I tried reseating the neck board and the connections that plug into it.
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#7
03-27-2009, 04:40 PM
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The CRT filament will likely be powered by the flyback. There is likely a low ohms (less than 10 ohms) resistor in the CRT filament line that's open. You could have an open CRT filament, an open winding on the flyback, or a cracked PC board trace. The far more likely culprit is the resistor in the CRT filament circuit if the filaments do not light but the set is alive otherwise.
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#9
03-27-2009, 05:09 PM
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It may be on the main chassis.
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#11
03-27-2009, 05:17 PM
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It's in Sams 4043. I'll see if I have a copy, I'll see exactly where the resistor is.
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#13
03-27-2009, 07:25 PM
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I don't have the Sams on that one; but, the CRT pin layout should be the same as for most other TV's of the period. The filament pins should be 4 and 5 and there should be something like a 2.2 ohm, 2 watt resistor connected between one of the filament pins and the flyback. The other pin should go to ground.
Pin one is the focus terminal (the one inside the triangle) Pin three is the blue cathode Pins 4 and 5 are the filament Pin 6 is ground Pin 7 is the red cathode Pin 8 is G2 (screen). Connects to the G2 lead from the flyback. Pin 9 is the green cathode.
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#15
03-30-2009, 03:29 PM
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Ooooh I think I just discovered why the CRT guns won't light. The neck board has a big ol crack in it... I didn't notice it before.
I'm going to try to glue it back together and fix all the solder traces... Wish me luck.
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| Audiokarma |
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