OK, PL706 PIN 3 is BL_ON and this signal goes out to the LED driver board.
The BL_ON is generated by the main board and it is fed to PL703 pin 15 and routed through a resistor then to PL706 PIN 3.
It looks like the BL_ON is active LO (LO= ON).
So you have BL_ON signal problem from the main board.
BL_ON is a steady state signal, it is either HI or LO, it can be that the Transistor or the MOSFET switching device is defective, nothing to do with refresh rate.
Vestel 17MB62 isn't the most reliable main board out there...... and if it does go bad, good luck finding the right replacement, because there are so many different versions.
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Yes, I've been reading about the number of different applications for this board, all with their own firmware, so it's unlikely I'll find the correct replacement.
Is it worth pursuing the problem on this board, or am I likely to be wasting my time?
If not, is there anything else I can test?
Note: I've powered it on this afternoon, and initially there was a fair bit of flickering. I've gone through the on-screen menus, trying different picture settings etc. Some settings make it flicker more quickly than others. "Normal" seems to be the best setting. "Game" and "Dynamic" flicker much faster. "Cinema" can also make it flicker.
Anyway, the picture stabilised in "Normal" setting, and is OK at the moment. Although I did notice that for a short period that the picture was brighter in the centre than at the sides. Dividing the picture into roughly 3 vertical sections, the 25% at each side was slightly dimmer than the centre 50%, if you see what I mean. That didn't last for long, though.
I shall leave the TV on for a couple of hours to see what happens.
Hi!
I'm writing this post because i've got a problem with this power board, but i've got the v3 revision (it comes from a sharp LC-24LE510E led tv).
I was using it, then suddenly the tv died.
I've checked the capacitors and the uf diodes, but the standby led is still dead.
I've also checked the power on the ic700, and it goes up and down from 10 to 16 V.
I've replaced also C715 due to the fact i believed it was the problem, but still nothing.
I recently joined this forum as I just retired. My granddaughters tv packed up so I thought this would give me something to interest and occupy me for a while. I followed the information on this thread, I have just fitted the diodes and it works Thanks everybody for the help I feel really delighted as I was mostly a manual worker using tools and parts not so delicate. Now the TV her friend gave her to use has no sound so now I'm off on another mission THANKS again dorango
First I founbd out that diode D700 had infinity Ohm's.
Then one of the D708, D709 and D710 was shorted. Juste replaced with 3
( just for a quick test ) 1N5408. Got hot and 1 burned short.
So, I learned at school taht when palcing didodes paralel, each one needs a serie resistor, cause the slyhtliest difference in the Uf/If curve gives problems.
Each diode ahs its own Uf altough they are very small in difference. But as we know in the diode-curves, small variation in Uf makes a giant leap in If.
You can't use 1N5408 here. It's not a "fast" diode. You must use UF5408, HER308G, MUR460, or similar.
1N5408 will fail regardless of it having a resistor. It's just no good in a switching power supply output stage.
Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
For service manual, schematic, boardview (board view), datasheet, cad - use our search.
Plug a source into the set, do you get sound? (Even without pic)
Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
For service manual, schematic, boardview (board view), datasheet, cad - use our search.
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