Voltage level on LCD power supply board.

[dcavman]

Re: Voltage level on LCD power supply board.

My meter was on dc it hit 320 and was slowly still climbing all the small caps had dotd on them.from the factory they dont seem bulged

[dcavman]

Re: Voltage level on LCD power supply board.

I tried that with no results im wondering if the 24v section isnt charging up fast enough

[dcavman]

Re: Voltage level on LCD power supply board.

If i let it charge i can get to the point where the lamps kick on real quick then shut off

[tom66]

Re: Voltage level on LCD power supply board.

If 24V is taking a long time to rise, that is indicative of bad capacitors on the 24V output.

[dcavman]

Re: Voltage level on LCD power supply board.

does any one know of a way to get a schematic for the power supply pcb it seems like im so close

[budm]

Re: Voltage level on LCD power supply board.

Did you try running the TV without inverters connected to see if the TV will stay on as I suggested, unless this TV has an error output signal from the inverter to shutdown the TV if it does not come on.
That rising voltage on the main DC cap can be due to bad PFC circuits not doing its job.

[dcavman]

Re: Voltage level on LCD power supply board.

I did try that but same results im thinking about shotgunning the caps cant hurt shouldent b to expensive

[dcavman]

Re: Voltage level on LCD power supply board.

Would it be a bad idea to inject a 24V signal in from an outside variable power supply

[dcavman]

Re: Voltage level on LCD power supply board.

The 300v tops out around 360 and bounces between that and 380 once its up that high the 24 comesup to 24-25vdc

[budm]

Re: Voltage level on LCD power supply board.

I expect it to be steady around 400Vdc (it should jump up to 400V really fast),I do not have the exact spec, but I do expect it to be very steady.
By the way, when the TV is just plugged in but in the OFF condition (power switch not activated), the voltage on that cap should be steady 170V (or if it is jumping around also) and not go up to 300+ until you activate the power switch on the TV.

[selldoor]

Re: Voltage level on LCD power supply board.

You did suggest at one point that the Big cap had leaked- I think I would try and replace that first although a bit expensive if its not the problem. Just as few further tests does it discharge fully - test after 2 minute and 5 minutes (Carefully in case it retains charge) and observe polarity. Next try pre heating the cap with a hair dryer and see if the 24 volts comes up quicker.

[dcavman]

Re: Voltage level on LCD power supply board.

I tested it in circuit its a 220uf i was getting pretty close i replaced the three freen caps the dark and light blue ones also a total of 7 caps replaced with no results im debating ordering a referb replacment for around 65.00

[dcavman]

Re: Voltage level on LCD power supply board.

Simply put someone got into this pcb and im not sure what they did if they did any thing its just the 24v that i can tell is the issue

[lilmonk3]

Re: Voltage level on LCD power supply board.

I just got this same set today... Plug in to AC and hear a slight click.. Stand by light is solid and it will not power on at all.. Got the back removed and dont see bulging caps.. All I have had time to do is check some voltages at the long plug on the power board.. Here are the results of that with the AC plugged in
---------
Boards connected -------- not connected
5v-m=6.8 -------- 6.1
5v-m=6.8 -------- 6.3
sw= 23.7 -------- 100+ and climbing
BR1= 3.7 --------- 100+ and climbing
12v= 1.7 -------- .01
12v= 1.7 -------- .01
5v-s= 4.7 ------- 4.8
5v-s= 4.7 ------- 4.8
Stb= 2.09 ------- 0

Something is jacked

*sorry that the spacing on the #s is messed up

[ben7]

Re: Voltage level on LCD power supply board.

I just got this same set today... Plug in to AC and hear a slight click.. Stand by light is solid and it will not power on at all.. Got the back removed and dont see bulging caps.. All I have had time to do is check some voltages at the long plug on the power board.. Here are the results of that with the AC plugged in
---------
Boards connected not connected
5v-m=6.8 6.1
5v-m=6.8 6.3
sw= 23.7 100+ and climbing
BR1= 3.7 100+ and climbing
12v= 1.7 .01
12v= 1.7 .01
5v-s= 4.7 4.8
5v-s= 4.7 4.8
Stb= 2.09 0

Something is jacked

*sorry that the spacing on the #s is messed up

Did you use AC or DC setting to take the measurements?

[lilmonk3]

Re: Voltage level on LCD power supply board.

did you use ac or dc setting to take the measurements?

dc

[ben7]

Re: Voltage level on LCD power supply board.

dc

Ok, that is definitely funky!

Well, I bet theres bad caps in there!

Whats the voltage on the big main filter cap?

[lilmonk3]

Re: Voltage level on LCD power supply board.

Ok, that is definitely funky!

Well, I bet theres bad caps in there!

Whats the voltage on the big main filter cap?

I will have to check it later.. Kiddo just had friends show up to swim. I will try to slip away and check it..

[lilmonk3]

Re: Voltage level on LCD power supply board.

Ok with AC plugged in 250v 390uf cap reads 1.83 as soon as the probes hit it, but this drops in a blink of an eye to .830

[ben7]

Re: Voltage level on LCD power supply board.

Ok with AC plugged in 250v 390uf cap reads 1.83 as soon as the probes hit it, but this drops in a blink of an eye to .830

Um, you have both probes on the capacitor leads? (+ on +, - on -)

If so, I think your meter might need a new battery, cheapy ones have been known to give wrong readings with a worn-out battery.