42LK450-UB Noob question

[budm]

Re: 42LK450-UB Noob question

At this point I suspect you have problem with the lamps, that is why the inverter board sends out Error (HIGH = Abnormal).
So more likely your old main board and the old inverter board are probably OK.
This last test you just did are done with the new boards, correct?

[budm]

Re: 42LK450-UB Noob question

Budm, look back at the troubleshooting chart on post #7. Main is looking for a low signal on error pin.

I saw that but I just want to make sure by actually forcing the Error pin just to be sure, so far I believe he has problem with the lamps.
I do not know for sure if the lamps have sockets are not, may be that can be the cause of the problem too.

[newkidontheblock]

Re: 42LK450-UB Noob question

At this point I suspect you have problem with the lamps, that is why the inverter board sends out Error (HIGH = Abnormal).
So more likely your old main board and the old inverter board are probably OK.
This last test you just did are done with the new boards, correct?

yes all new equipment.

[will62]

Re: 42LK450-UB Noob question

Budm, what do you think about bypassing the protection on the inverter driver IC, so he can ID lamp not lighting or possibly flickering?

[budm]

Re: 42LK450-UB Noob question

Budm, what do you think about bypassing the protection on the inverter driver IC, so he can ID lamp not lighting or possibly flickering?

Yes, he can do that just for testing purpose only.

[will62]

Re: 42LK450-UB Noob question

Newkid, if you want to try it, get me the number on the IC circled in the pic on post #44 (16 pins).

[newkidontheblock]

Re: 42LK450-UB Noob question

it is OZ 9937GN

[will62]

Re: 42LK450-UB Noob question

You can bypass the protection of many of the driver ICs by jumping the timer pin directly to ground. Unfortunately, for the OZ9937, they recommend using a 47k ohm resistor to jump pin 14 (timer) to ground. I'm not sure why such a high ohm value is needed, but I wouldn't chance using a lower value. I believe you only have 1k resistors, so that's a no-go. Oh well...

[budm]

Re: 42LK450-UB Noob question

Can you please upload the spec sheet?

[will62]

Re: 42LK450-UB Noob question

Couldn't locate complete datasheet, just brief overview of O2 Micro's driver ICs.

[newkidontheblock]

Re: 42LK450-UB Noob question

I doubt it helps, but when the screen was on during a previous jump, with a full white screen, I had no dark spots. But it was only on for a few seconds

[budm]

Re: 42LK450-UB Noob question

You cannot doubt until you try it, right now the Inverter board is sending out the Error signal for reason.
It will not be dark spot, it will be light grey band across the screen that you will have to look at it in the dark room.

[will62]

Re: 42LK450-UB Noob question

(Let's get Budm's input on this before trying.)

I noticed on the inverter board, just outside of the high voltage area, there are test points coming from the HV caps. These could be capacitive voltage dividers, bringing the voltage down to logic level, so the chip can monitor the voltages.

If you have a max voltage capture on your DMM (AC), you could test each one and see if you find one that's off from the others. You'd have to power off then on for each test. Wait a while after each, so caps can drain and chip will reset. If you decide to try it, be very careful with your probe in that area.

[budm]

Re: 42LK450-UB Noob question

OK, I just re-read pot 1 and realized that the Inverter board was not replaced and the Transformer High Voltage windings resistance are not tested, it may be worth to test them first.
I am not 100% sure what that test points are, they look to be part of the lamp detection circuits and I am afraid if probe may slip and that can be bad news.
Can we get the P/N as printed on the transformer so we can get the pin out?
Also need good clear close up pictures in the area of those test points to see what circuits in those section are.

http://assets.shopjimmy.com/media/ca...14.001-top.jpg
Looking at the picture from shopjimmy. it does not look like all those test points are connected in the same fashion.

[vinceroger69]

Re: 42LK450-UB Noob question

in post 22 i did ask for the transformer part number but cant find any info on them, also in post 52 can you confirm if you did purchase a new invertor board and have tried it.

[budm]

Re: 42LK450-UB Noob question

The thread is getting long so I did not re-read all the posts.

[vinceroger69]

Re: 42LK450-UB Noob question

The thread is getting long so I did not re-read all the posts.

info that got posted regarding the transformers

tz.6502x101 B6fy01-03

ive had a search can find any data on them?

[budm]

Re: 42LK450-UB Noob question

OK, he needs to check the resistance between:
pin 1 (bottom left corner) against pin 7 (top left corner)
Pin 1 (bottom left corner) against pin 6 (top right corner)
Pin 7 (top left corner) against pin 6 (top right corner)

[vinceroger69]

Re: 42LK450-UB Noob question

how many hours roughly is a tv ccfl tube meant to last through normal use? as some ccfl light tubes like used in kitchens etc dont seem too last long at all.

[budm]

Re: 42LK450-UB Noob question

Most of the LCD panel spec show CCFL rating of 50,000 Hours.