On Nov 20, 8:43*pm, playedataritoday
wrote:
I was given this TV today to try and repair. *I know the power
supplies on this model have been a big problem, but before I buy a
replacement I wanted to run the symptoms by you guys.

It was working for a while on tuner mode and then got stuck on one of
the inputs and would not allow for it to be changed. *It was used like
this for a few weeks and then got stuck running in the test pattern.
Every 5 seconds or so a different color screen would show up and then
sometimes the full color bar test pattern. *I took the back off and
took the following measurements at power supply connectors both when
the unit is on and when it is in standby.

CN102
* * * On *(Standby)
1 - 12.09 (0)
2 - 12.09 (0)
3 - GND
4 - GND
5 - GND
6 - GND
7 - 5.11 (5.11)
8 - 5.11 (5.11)
9 - 5.11 (5.11)
10 - 3.47 (.062)
11 - 3.57 (.627)
12 - 4.87 (.006)

CN101
* * *On (Standby)
1 - GND
2 - GND
3 - GND
4 - GND
5 - 23.75 (0)
6 - 23.75 (0)
7 - 23.75 (0)
8 - 23.75 (0)
9 - 3.57 (.627)
10 - 4.87 (.006)

I removed the power supply completely and can see no evidence of
faulty capacitors and the voltages all seem to be in range. *My only
concerns are the On/Standby voltage being 3.47V, although I don't have
the schematics so I am not sure what it should be. *I might have
expected something closer to 5V. *If that is the expected value I may
try to strap an external 5V supply on and run as a test.

At one point using the top switches I was able to change the input
mode to VGA, and I am now driving it with a netbook and it gives me a
beautiful picture, I just am unable to change it to anything else. An
the OSD window for "Main:" stays on the screen. *The voltages at P701
(top side switch board) are as follows:
* * * * *On (Standby)
Orange - 0 (3.77)
Blue - 3.74 (3.77)
Red - 3.74 (3.77)
Green - 3.74 (3.77)
Yellow - 3.74 (3.77)
Black - 0 (0)
Brown - 3.74 (3.77)

Has anyone seen similar symptoms with their set? *I have no problem
dropping money on the replacement supply, I just want some confidence
the problem isn't with the motherboard before I invest anything more
than my time. *No post that I could find described symptoms similar to
what I am seeing. *Also does anyone have the schematics or repair
manual for this set? *If so please send me copies via email.

All help is appreciated.

Stephen


I bet you're wrong on the capacitor issue. I replace so many caps at
work I'm the 'cap guy' that gets most stuff working again for next to
nothing. Hints: If a cap looks bad it probably is but if it looks OK
it may actually be bad. Look for a brown 'mist' around a capacitor.
Those must be removed, the acid mist cleaned off a a new cap
installed. It will often have a 'fishy' odor. Without the mist it may
still be bad and look fine. The high voltage (300-500Volt) caps rarely
fail. The 22 -100uF low voltage caps frequently fail and the worst are
surface mount 'lytics. I replace LOTS of those. Many times a 'lytic
will have a ceramic in parallel. This might look OK on the tester
(Cheapest I know of is the MAT Electronics MUL-3333 at $50) as the
meter is seeing the ceramic but the 'lytic is bad. Only way to verify
is to remove the cap and test it by itself. It will read better while
its warm and as it cools will get worse. Rule of thumb: if there are a
lot of the same value and some are bad, replace them all. Look for
highest ripple current in the Digikey (and others) catalog. Often it
will be a Panasonic FM or FC or Nichicon HL HM HN, HZ for through
hole. I like Panasonic FK or FP for surface mount.

G²