Sanyo DP32628 display turns off

[budm]

Re: Sanyo DP32628 display turns off

I reedited my post after looking at the tv again. I was wondering if I could test this board with it unpinned from the tv, because I can see there are electrical terminals underneath.

The inverter board? You have to have everything connected, those black plastic on the TV are the sockets for the inverter board and the lamps inside the panel.

[hairywbush]

Re: Sanyo DP32628 display turns off

ok i just did it. for some reason the display/backlight kicked off really soon this time so i couldn't catch it early, but right now the volts at the STB terminal reads 3.2. I think I heard a really faint squeak too.

[budm]

Re: Sanyo DP32628 display turns off

ok i just did it. for some reason the display/backlight kicked off really soon this time so i couldn't catch it early, but right now the volts at the STB terminal reads 3.2. I think I heard a really faint squeak too.

OK, so backlights ON command stays on, but how about the 24vdc?

[hairywbush]

Re: Sanyo DP32628 display turns off

I didn't catch this part. Where is this 24vdc that i need to test? I assume this on the yellow board but I can't tell what I need to be looking at over there. there's 2 chips and to the right it says
5v
12v
24v

[budm]

Re: Sanyo DP32628 display turns off

Look at the inverter board connector.

[hairywbush]

Re: Sanyo DP32628 display turns off

I see what you're talking about now. it's on the other end of the connector, coming from the main board. Alright it's a 10 pin connector. 1-5 24.2/3v & 6-10 GND. That checks out! I don't see an issue there.

[budm]

Re: Sanyo DP32628 display turns off

How about the STB (BL-ON backluights ON) signal? It should be <1Vdc when TV is OFF, and more than 2.5VDC when backlights are ON.
ADJ pin =???vdc
STB = ????VDC
What is the '1-5 24.2/3v & 6-10'

[hairywbush]

Re: Sanyo DP32628 display turns off

the STB on was 3.2. I just had it off and it was 0.0. iit's been off since my last post if that makes a difference..but I turned it on to check again and now the tvs backlight is staying on. I'm at about 2 mins with it on At the moment. I haven't messed with anything and it's all still connected.

[budm]

Re: Sanyo DP32628 display turns off

If the 24VDC and the STB are present but the backlights go off, then we know it is not power supply or main board problem, that is why we need to narrow first, if those two are present then it can be either bad inverter board or bad lamp/s.
Never mind, your inverter board does not have fingers for the lamp sockets.
Those four electrolytics caps should have the capacitance and the ESR tested to make sure they are OK.

[hairywbush]

Re: Sanyo DP32628 display turns off

you mean the bulb connections? I'll wipe them like you say. can I use dielectric grease on them or anywhere on this board?

[budm]

Re: Sanyo DP32628 display turns off

So the backlights are still staying on?

[hairywbush]

Re: Sanyo DP32628 display turns off

they unfortunately are turning off again. it was on for a good 10-15 mins. wasn't paying too much attention at how long.

[budm]

Re: Sanyo DP32628 display turns off

I do not expect bad inverter board to stay on that long but I can be wrong, but the lamps can go bad after they are heated up to the running temperature.

[hairywbush]

Re: Sanyo DP32628 display turns off

why would they stay on for so long this time

[budm]

Re: Sanyo DP32628 display turns off

Yo may have poor connections on the lamps sockets, you need to open up the panel to inspect the lamps and the sockets.
And just to be sure, you still need to test the capacitance/ESR of those 4 caps, as temperature goes up, the ESR will go down may make the circuit operate little better.

[hairywbush]

Re: Sanyo DP32628 display turns off

which caps are you referring to? and do I need some tool to test esr?
i'm about to try and open up the back of the screen. anything I should be careful of? I see screws hold it from the perimeter.

[budm]

Re: Sanyo DP32628 display turns off

There are 4 electrolytics caps laying on its side on the inverter board, you need capacitor tester that can do the ESR testing, or cheaper way will be replacing them with low ESR type caps not general purpose caps and see what happen.

[hairywbush]

Re: Sanyo DP32628 display turns off

hey bud, I took the screen apart (it was actually only 10 screws) and here's what i found. that one is clearly burnt. the other marks you see in the other pics is just in the plastic so maybe they're ok?
edit: I took off the platic that covers them. easily at least 2 burnt.

[budm]

Re: Sanyo DP32628 display turns off

You found the problem. It looks like it has high contact resistance between the end of the lamp and the socket so it heats up and cause more bad contacts, or the lamp is badly worn out an the end of the lamp turns red hot. See pix of what bad lamps will do to the wires.

You also need to look at the end of the lamps to see if they lots lots of blackened ends which will mean worn out lamps, you will have to remove that white plastic to see the ends of the lamps.

Pix of bad lamps:
http://s807.photobucket.com/user/bud...?sort=3&page=1

[hairywbush]

Re: Sanyo DP32628 display turns off

wow I'm lucky I don't have it that bad! yea I'm looking closer and I think it would be best to replace the ones that even look suspicious. where can I get a few of these?