CurtPalme.com Home Theater Forum

[Nashou66]

A customer found this TV in the Garbage and brought it to me cause he knows I like to tinker with Electronics.
It has no Remote, it powers up and for a split second the input its on comes up and then goes black.

When its black i can press the input button and change inputs as when i turn it off and on again the new input shows for a for a split second then goes black.

A few times it would have the blinking power light and pressing the Volume up and Channel down while plugging it in fixes that .

I found this on FIXYA site

http://www.fixya.com/support/t1316338-sharp_aqous_lc_37_in_tv_power_no

Your control board seem's defective or the inverter board (associated circuits) are bad. This is common in most TFT-LCD Tv's.......


Mac or Curt any suggestions?

Athanasios

[macgyver655]

Fixya.......hahahahahahaha. Those people pretty much don't know anything.

Send an input through it. Do you still have sound? Shine a flashlight at an angle and see if you can see an image.

[Nashou66]

[Nashou66]

Ok Mac, I have sound and I can see an image with the flash light on. Also sometimes on power up the green power light will flash and pressing the power button again makes it go solid Green on.

Bad back light ?

Athanasios

[macgyver655]

These model Sharps had a lot of lamp problems. Could be 1 or more bad lamps. Could be inverter. I think inverter and P/S are the same board.

[Nashou66]

Ok I'll open her up and Check out caps first on the PS.

What does the inverter board do?Should I look there for bad caps, diodes etc?

And how can I test the lamps?

Can i remove them and hook up to a power source with the correct voltage?

Athanasios

[macgyver655]

[macgyver655]

Here's an image.

[Nashou66]

Ok i'll dismantle it and look for the lights to come on.

Also a few times before i had the source on the whole screen would light up with snow( on cable input no connection), then it go dark. the entire screen was well lit. Then the power light flashed. I forgot about that info.

Athanasios

[Nashou66]

Ok I got the covers off.



Power supply/Inverter board caps look fine. No Bulges.



Now on the front there are screws with arrows on the metal shroud pointing to them, I assume
those are the ones I remove to gain access to be able to see the lamp assembly. Also I assume
I'll need to some how flip up and prop the LCD panel to keep the two large ribbon cables in this next photo connected .



Anything I should know before doing this?

Athanasios

[Nashou66]

Ok Got the front panel off. One lamp is out, but they do not look cracked or burnt. I caught this pic just when the lamps were turning off.



And then i took a pic of the LCD panel of the snow while it was frozen as the unit shut down. I was under the panel looking up as my shop light shown down. No reason just thought it looked cool.



So not sure if the lamp is dead or the power for that single lamp.

but while it was powered up i saw the ANT and Channel 3 on the LCD panel.
Si it definitely is the PS or Inverter not keeping the lamps on.

Athanasios

[macgyver655]

One lamp not working will cause shutdown. Each transformer on the inverter powers 2 lamps so I would not think its the inverter. Probably the lamp. You could try moving that 2 lamp section to another spot which would then be powered by a different transformer just to verify.

[Nashou66]

[macgyver655]

[macgyver655]

I was just looking at a picture of your inverter and I may have to change my wording from the above post. Since I dont know exactly how your lamps are wired and connected you may have to fill me in. Yours may use 2 sockets for a 2 lamp pair or each lamp separately. Let me know what you have and I'll advise.

[Curt Palme]

Nashou, an open circuit or short/overload will be sensed by the inverter supply, and the set will shut down. My guess is that the one tube is bad.

I've had two recent occasions where the inverter transformer was arcing internally, but that was on a Samsung computer monitor, and one transformer with two windings drove the two backlights. One winding was arcing internally causing the shutdown. I doubt that's the case here.

[Curt Palme]

Nashou, an open circuit or short/overload will be sensed by the inverter supply, and the set will shut down. My guess is that the one tube is bad.

I've had two recent occasions where the inverter transformer was arcing internally, but that was on a Samsung computer monitor, and one transformer with two windings drove the two backlights. One winding was arcing internally causing the shutdown. I doubt that's the case here.

[Nashou66]

Thanks Guy's, Mac, I think they are socketed individually . Those 10 black "boxes" on the right side of the inverter go to each lamp in the assembly. From memory I did not see any wires to each lamp, not sure how they are fed power. But I may have just overlooked it.

you can seethere are 5 transformers so i think you might be right about one driving two lamps. I'll check if they are in series.

Curt I hope its not a lamp as it looks like a real pain to get them out on the socket ends. I think I'd have to remove the entire assembly.

Still at work, so I'll check back later.

Athanasios

[Nashou66]

Ok they are in series. On the ends I thought it was one complete assembly but I looked closer and the end covers come off and expose each socket. they are like the sockets used for fuses and just snap in.

the right side of the assembly is where the PC board that connect two lamps in series.

I could remove the bad lamp and swap it into another location just to be sure. those things are delicate and I have some thing else to go to now, so I'll do this later and report back.

Athanasios

[Nashou66]

Ok I tested it in another location and its dead. So I ordered one online from CCFL Wearhouse for 19.95 and 5 buck shipping.
It is a 3mm D and 705mm L .

E-bay had them as well but only 10 for 99.95 and I didn't want to buy them all.

Thanks guys !!!

Athanasios

[Nashou66]

Thanks again to Curt and Mac !!! I ordered the wrong diameter lamp 3mm and I think mine is 4mm but it works. What sucks is there are these little clips that go onto the lap leads. well they are crimped on and the clips have that metal that is impossible to solder to. So on the first one i mangled it. So i tried to scratch the clip and fold over the lead to solder it to the clip that slides over the tube lamp. I decided to fold the lead under the clamp so the light and clamp and Assembly clamp( where power comes in contact to other clamp) hold it tight. the other i cut the existing lead where some of it was still accessible and soldered the new lamps lead to it.

fired it up and all lamps are on, fed it a HDMI signal and it works fine!!!



Athanasios