lg 42pt85 no power standby lights up

[wreksta]

hi again got another set in this had blown caps on psu I replaced them but still the standby flicks to green then back to red


now the only caps I changed were the 3300uf 10v's

I know in the kit its says relace the 680uf 50v and the 100uf 50v

I tested voltages from psu with parts z and y disconnect

all checks out apart from vs and va very low 2-3 volts only

any ideas

[wreksta]

Re: lg 42pt85 no power standby lights up

also notices another repair kit for these
I consist of 2 x diodes 2x resistors 2 mosfets and the ic

anyway t test if its this kit I need

[wreksta]

Re: lg 42pt85 no power standby lights up

What is this 68n pilkor blue box ive heard tom mention in a few threads

my vs and va are very very low 3v and 5v

[tom66]

Re: lg 42pt85 no power standby lights up

Unplug Y-sus/Z-sus and check if Vs/Va rise.

[wreksta]

Re: lg 42pt85 no power standby lights up

No iTs the same mate

[wreksta]

Re: lg 42pt85 no power standby lights up

any other checks to do tom im with it now going to have a tinker with it
recheck all voltages and post all findings

[tom66]

Re: lg 42pt85 no power standby lights up

Check PSON/VSON
Look at control board LED should be flashing continuously if working or a pattern if not e.g. 2 long 2 short.

[wreksta]

Re: lg 42pt85 no power standby lights up

tom this kit has a few parts that I can go off and check on the board but there is a fuse in there my fuses are not blown

the kit is for no vs or va voltages

http://www.ohmsupplies.co.uk/epages/...roducts/KIT248

busy getting reading now

[wreksta]

Re: lg 42pt85 no power standby lights up

Check PSON/VSON
Look at control board LED should be flashing continuously if working or a pattern if not e.g. 2 long 2 short.

even in standby

[tom66]

Re: lg 42pt85 no power standby lights up

Control LED? No, only in operation.

[wreksta]

Re: lg 42pt85 no power standby lights up

tom here is my voltages with z and y disconnected

METER SET TO 20 VDC

Tv LIGHT is flashing green

NO CONTROL LED LIT

these are lit on the main board
D3
D4

D1600
D1601

D901

VOLTAGES ON PSU

VS = 0.94
VS = 0.94
NC = /
GND = 0
GND = 0
VA = 1.39
GND = 0
5V = 4.99



3.4V = 4.44
NC = /
6V = 5.99
NC = /
GND = 0
STBY 5V = 4.90
M5V ON = 5.02
5VMNT = 4.99
VS ON = 4.45
GND = 0
STB5V= 0
RL ON = 4.44
AC DET = 5.15

GND = 0
12V = 11.99
GND = 0
3.4 = 3.39
GND = 0
6V = 5.99
GND = 0
GND = 0
19V = 19.35
19V = 19.35

[tom66]

Re: lg 42pt85 no power standby lights up

OK, so you have power LED on TV? In standby red or orange I believe.
Then you press power button, it turns on, while doing this, check VS ON, and PS ON.
The control board LED should start flashing as soon as power rails come up.
Also recheck 3.4V should not read 4.44V, I think that's a typo.

[wreksta]

Re: lg 42pt85 no power standby lights up

hi tom from moment I put power to the set the light goes straight on to a flashing green

I only have ac det or rl on

[tom66]

Re: lg 42pt85 no power standby lights up

OK, once set powered on can you put it back in standby?

[wreksta]

Re: lg 42pt85 no power standby lights up

yes mate
thinkso

[tom66]

Re: lg 42pt85 no power standby lights up

K, it's just auto powering up then, which some TVs do.
Check the PSON and VSON when it goes into standby. They should drop to nearly 0V.
And did you recheck that 3.4V measuring 4.4V?

[wreksta]

Re: lg 42pt85 no power standby lights up

tom the 3.4 is measuring 4.44 and other connector 3.4 is 3.39

not sure on ps on so checked all on pins whilst powering down the set standby mode
vs on 4.45 dropped to 0.0.2
rl on 4.44 dropped to 0.0.2
m5v on 5.02 dropped to 0.07

[tom66]

Re: lg 42pt85 no power standby lights up

OK, if you have low Vs/Va without Y-sus/Z-sus and those RL ON etc readings you have a defective PSU. Would advise you post pictures for quick diagnostics that may be possible.

[wreksta]

Re: lg 42pt85 no power standby lights up

tom I have a few diodes and resistors they have condinuety cant spel it lol this is of course on the board ill point them out on this picture

there is a mosfet to top right hand side

[tom66]

Re: lg 42pt85 no power standby lights up

C-o-n-t-i-n-u-i-t-y. Continuity.
Can you take a top down picture, and of the whole power board? Plus one of the bottom, green side.