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pensacol



Joined: 02 Jul 2009
Posts: 30

PostPosted: Fri Jun 04, 2010 10:27 pm    Post subject: Samsung TX-P2670WH Reply with quote

Got this tv from somebody, and it wouldn't turn on. Power light just blinked. They said they had an estimate done on it and they said it was the HOT and a couple resistors. They cut the leads on the hot which had been replaced before because it's not the original. Does anybody know where I could find a service manual for this set (chassis model K60A)? Or are there and updates to this board or common problems? It's a really nice tv and I would love to see if I could get it fixed.
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pensacol



Joined: 02 Jul 2009
Posts: 30

PostPosted: Thu Jun 17, 2010 10:09 pm    Post subject: Reply with quote

Update: Found a cracked solder joint on the flyback, the pin connected to the collector of the HOT. HOT was shorted I'm guessing cause of the cracked joint. Set still will not turn on. Only get 3 blinks on the power light. No power to the main board at all. Figuring something in the power supply. I get 160vdc across the main filtering cap off the rectifier, but if I go from positive to ground on the board I only get 88vdc. I have checked every diode on the board thinking one was leaking to ground but they are all good. Here are a couple pictures, and I have marked where I checked the voltages. I have also included the power supply schematic. Could somebody please take a look at it and see what I might be able to check. Also. You will see the jumper that I soldered across 2 pins on the board. That was a 4 amp pico fuse that was blown. The jumper was there for testing so don't worry I put a 4 amp fuse across it before I applied power the first time Very Happy Thanks guys. Hopefully somebody can help me.

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kuhurdler



Joined: 28 Dec 2006
Posts: 2858
Location: Overland Park, KS

PostPosted: Fri Jun 18, 2010 5:54 am    Post subject: Reply with quote

Which gnd are you using. If its earth ground 1/2 of your b+ makes sense. Usually earth ground is in the middle of the bridge rectifier.
pensacol



Joined: 02 Jul 2009
Posts: 30

PostPosted: Fri Jun 18, 2010 8:14 am    Post subject: Reply with quote

Straight across the main filter cap off the rectifier I get 160v, to any other gnd I get 88v, tried heatsing gnd, the one on the bottom left of the "bottom of board" picture, and the soldered trace lines right to the right of that gnd.
JTS1957



Joined: 21 Jan 2009
Posts: 2328
Location: Far, Far Away

PostPosted: Fri Jun 18, 2010 12:20 pm    Post subject: Reply with quote

What about secondary SMPS (reference TUNER ground) voltages?
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pensacol



Joined: 02 Jul 2009
Posts: 30

PostPosted: Fri Jun 18, 2010 5:54 pm    Post subject: Reply with quote

If you look at the diagram for the sub power board (above link) this is what i get off the SMPS to reference ground:

Pins 18,17,16,15,14,13,12,10 off the secondary to reference = 0v
positive probe Pin 1 to negative probe pin 18 = 89v
positive probe Pin 1 to negative probe pin 2, 3, or 4 = 160v
JTS1957



Joined: 21 Jan 2009
Posts: 2328
Location: Far, Far Away

PostPosted: Fri Jun 18, 2010 6:06 pm    Post subject: Reply with quote

Now let's try that again, taking the DC voltage readings across these capacitors:
C801 / C802 / C814 & C823

T801S Pins 12 & 15 are secondary (cold / tuner) grounds.
pensacol



Joined: 02 Jul 2009
Posts: 30

PostPosted: Sat Jun 19, 2010 7:02 am    Post subject: Reply with quote

0v across all of those. One more thing. Do you want me to take those readings with the set on or off? Let me know and if I need to I'll check them again with it on. Power supply had power but unit was not officially on. But of course it won't turn on either.
JTS1957



Joined: 21 Jan 2009
Posts: 2328
Location: Far, Far Away

PostPosted: Sat Jun 19, 2010 1:31 pm    Post subject: Reply with quote

Try it both ways.
pensacol



Joined: 02 Jul 2009
Posts: 30

PostPosted: Sat Jun 19, 2010 8:25 pm    Post subject: Reply with quote

Yeah, I got 0 volts on all those caps with the set on or off. I put the clips on the see if it would move at the moment it was turned on and nothing. So I guess I'm not getting any secondary voltages? I'm still learning switch mode supplies, but insent there an occisilator or something that drives the transformer to produce the secondary voltages? I'm not quite sure but from what I've read it seems like that's how it happens. What can I check? I really appreciate all of ya'lls help. This is the best tv repair forum I have found yet.
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