Riddled TV Repair Forum

jasonc · Joined: 04 Sep 2008 Posts: 4

samsung 42" projection tv
model HCM4216WX

The problem started with the tv picture taking 5 minutes to come on, then 10 minutes, then 15...eventually taking 30 minutes to get a picture. Now it has sound but no picture at all no matter how long it's on. I took the cover off and there are no obvious problems. I have a good multimeter and electrical experience (mostly automotive).

Any help would be greatly appreciated
Thanks,
Jason

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Jesse Mack · Joined: 22 May 2008 Posts: 600 Location: The Last Frontier

Unplug connector GT404 (Screen) on the sub pcb (This is the board that has the HV transformer on it. This transformer has a big red wire coming out of the top of it.) GT404 will be close to the transformer.

If set powers on after unplugging this connector, you will have to purchase a new red crt pcb and make a modification to the sub pcb.

Jesse

jasonc · Joined: 04 Sep 2008 Posts: 4

I want to clarify. The tv allways powered up and had sound but slowly lost picture.Now there is no picture. I found gt404 and disconnected wire (pink). There was no change. what should the voltage be at gt404? Any other Ideas? what to check next?

Thanks,
jason

Jesse Mack · Joined: 22 May 2008 Posts: 600 Location: The Last Frontier

Please be carefull, the DC level can be anywhere between 150 VDC and 800 VDC depending on current draw.
I apparently had a brain cramp and missed that you still had sound.

You need to do a visual check of IC301 vertical Ic for signs of heating. look at CRT boards for signs of overheating resistors. Check connector CNZ03 pins 1 & 4 for + and - 20 VDC. Do a visual for burnt resistors around convergence chips. (two large heat sinks side by side)

Hope this helps.

Jesse

Note: Going hunting for moose with 12 year old granddaughter all of next week. (I live in Alaska)

jasonc · Joined: 04 Sep 2008 Posts: 4

I have 22.86v on the + and 1.566v on the - of cnz03. little fuse (10A)in the - circuit is blown. What would cause this fuse to blow?

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Jesse Mack · Joined: 22 May 2008 Posts: 600 Location: The Last Frontier

You most likely have bad convergence IC's. The fuse opens as a direct result of too much current being drawn by the convergence IC's. Replace them as a pair and do a careful visual of the low value 1 watt resistors in and around the convergence IC's. When the IC's go bad, many times there is a resistor or two that burn up due to the excessive current.

Hope this helps.

Jesse

jasonc · Joined: 04 Sep 2008 Posts: 4

I found the bad little fuse and a bad ic diode. I could not find the parts for it so I bought a remanufactured power/deflection board. problem solved.
Thanks for your help!

Jason