Sharp Aquos 32"

[tom66]

Originally Posted by rigeback

Tried connecting the PC again with softMCCS http://www.entechtaiwan.com a good little program to learn what the software is doing inside the TV but it does not see the LCD and its now obvious that there is no power at the serial connector nor SCART / HDMI connectors, this area is dead! Need to find the supply point??

You might have a bad LDO or a bad switching controller/diode.

Post some close ups of the areas highlighted...

[rigeback]

I hope these will identify the parts that you mentioned, I added one extra near the scart connectors,
Cheers.

[tom66]

Okay... lots of checks... and this is the first image. If these checks pass, we'll have a look at the rest.

RED circled components are diodes. With the TV off (no standby, either) use the diode test setting to check if the diode is shorted. It should measure from 150-600 one way and infinite ("1 ." or OL) the other way. If it measures less than 30 both ways, it is definitely shorted and this will cause a supply on the board to not function.

The BLUE circled components are all resettable fuses. These fuses temporarily trip if current is exceeded; when the current subsides or after a period of time, they will reset (like a circuit breaker). However, due to their nature of operation (rapid heating), if they are subject to many trip cycles they can permanently fuse and fail open. Test using your multimeter's ohm range. A polyfuse less than 3 ohms is good (most polyfuses have a significant, non-zero resistance, of a couple ohms.)

The GREEN circled component is a Sharp voltage regulator (fancy that, Sharp use their own parts. Beats an LG plasma I have seen which used Panasonic driver ICs for the Y-sustain. Heh.) All measurements relative to the case of the TV, board installed, and TV turned on with fault. Pin #1, counted from the left as in the image, is the input, measure this. Pin #2 is the ON/OFF pin, it should measure >2.0V. Pin #3 is the output, it should be >1.2V (we'll determine exact output later.) Pin #4 is the voltage adjustment terminal, it should be ~1.2V. Pin #5 is ground, don't worry about measuring this, and the metal tab is the output pin - be very, very careful not to short input to output or you could fry your board - use the tab to measure the output voltage if it makes it easier.

[rigeback]

Yes you're right there is a fuse that measures 3.8 ohms and 2 others that 2.2 ohms, the rest are between 1.0 - 0.9 ohms.
I've quoted all the measurements because mine are slightly higher than yours!
For Sharp IC-1726 Pin 1 = 12.91V Pin2 = 3.6V Pin3 = 8.16V Pin4 = 2.62V Pin5 = GND
For IC1701 Pin1 = 1.21V Pin3 = 4.29 Pin4 = 3.91V Pin5 = 3.25V
Thanks for the help.

[rigeback]

Originally Posted by rigeback

Yes you're right there is a fuse that measures 3.8 ohms and 2 others that 2.2 ohms, the rest are between 1.0 - 0.9 ohms.
I've quoted all the measurements because mine are slightly higher than yours!
For Sharp IC-1726 Pin 1 = 12.91V Pin2 = 3.6V Pin3 = 8.16V Pin4 = 2.62V Pin5 = GND
For IC1701 Pin1 = 1.21V Pin3 = 4.29 Pin4 = 3.91V Pin5 = 3.25V
Thanks for the help.

I forgot to mention that the diodes you outlined were all OK.

[momaka]

I haven't looked at the service manual yet, but I think tom66 has the right idea to check the rest of the voltage regulators. I see a few more.

Starting with this picture, check IC2303 (left-middle side of the picture, close to the 2 electrolytic capacitors):
http://www.badcaps.net/forum/attachm...6&d=1324947839

On this picture measure voltage on the pins of IC4202:
http://www.badcaps.net/forum/attachm...3&d=1324944651

I wonder what the 8-pin ICs with v5805 do. Check voltages on all pins and post back. I wonder if these could be 5v linear regulators.
http://www.badcaps.net/forum/attachm...4&d=1324944651

Measure voltage on IC1755 and check the 2 fuses to the left of it.
http://www.badcaps.net/forum/attachm...5&d=1324944651

Lastly, measure voltage on the pins of the IC between the antenna input jack and the card slot. The IC is right below electrolytic capacitor C4420. There's also a 3.3v test point to the right of C4420. Check if that test point gets 3.3v.
http://www.badcaps.net/forum/attachm...2&d=1324333526

[rigeback]

IC2303 From top side pin1 & Pin2 = 3.24 Pins 3 & 4 = 0 volts and pin5 = 0.30V athough when I probe pin5 the back light of the screen suspends for a few seconds with a hissing noise and then returns.

IC4202: Pin1 = 3.20 pin2 = 3.18V Pin3 = 2.44V Pin4 = 1.21V Pin5 = 0 Volts

I've indicated measurements for both IC's but there are very slight veriations:

IC1745 Pin1 = 7.15v Pin 2 = 12.97V pin3 = 3.17V pin4 = 0V Pin5 = 0.79V Pin6 = 1.33V pin7 = 3.07V pin8 = 1.97V

IC1735 Pin1 = 8.77V Pin 2 = 12.87V pin3 = 4.88V pin4 = 0V Pin5 = 0.79V Pin6 = 1.40V pin7 = 3.07V pin8 = 1.97V

IC1755 Pin1 = 2.86V Pin 2 = 2.14V pin3 = 1.18V pin4 & 5 = 0 Volts Both fuses 1.7 ohms

The IC4410 just below C4420 has 5 Volts on pin5 the rest are 0 Volts, test pont 3.3V has 3.29 volts

[rigeback]

I've uploaded this manual in 5 parts incase anyone wants to have a look, I know its the holidays but please keep me in mind, part will uploaded later!

[rigeback]

And this is part of part 6 of the Sharp 26"
Happy New Year Everyone.

[rigeback]

These are the last schematics of the manual if someone can point me in the right direction, thanks.

[rigeback]

After re-testing the diodes and going back to Toms message with picture #1 it seems there could be a bad diode, far right next to the ribbon connector, it measures 174 com / cathode and 280 opposite, would this suggest its shorted since the most of the others measure infinity "1"?

[tom66]

Originally Posted by rigeback

After re-testing the diodes and going back to Toms message with picture #1 it seems there could be a bad diode, far right next to the ribbon connector, it measures 174 com / cathode and 280 opposite, would this suggest its shorted since the most of the others measure infinity "1"?

You will have to remove it and re-test, as the rest of the circuit could be altering the measurement.

It is probably okay; most diodes fail shorted, although there is the possibility a diode could become "leaky" if it fails.

[rigeback]

Tom, I was reading one of you posts within this forum that you recommended heating the board with a hair dryer, I might give this a go myself before de-soldering the diode!

[rigeback]

Well I didn't remove the diode as yet because I've disscovered that I have no power going to it and the t-con area after leaving the unit on for some time. I've lost power on
VGH35V and VGL-6V, VCC 1.5V , VCC 3.3V and VLS15.6V any clues to why this has happened much appreciated!

[tom66]

That might be a standby mode problem. Are you getting good supply voltages from PSU? Same voltage on both ends of fuses? Trace the voltages across the board and see where they disappear.

[rigeback]

Yes all the fuses had power across but some of the diodes in that area were dead on both sides including the one I was going to remove, seems theres a regulator not working like Q8408 but it also was dead, other parts of the board are mostly OK apart from AMP +13V bottom side, that was also dead.

[rigeback]

Made another cold boot check and the t-con is still dead, IC 1755 puts out 3V on one pin so maybe it has a fault, AMP+13V is back on line but otherwise I'm lost! Some of the fuses do read 20-30 mv less across but I don't think this could causing the drop out in the t-con area. I'm considering buying another board but the vendor doesn't have one in stock at present.

[rigeback]

Well the rest of the board has the same readings as indicated in message #27 although the 3 test points in the t-con area are still dead including 6V TP, theres 13V on the fuse and D8410 but the rest is dead???

[popeye]

Have you tested the ccfl back lights they go on this model you will find one of the lamps at least is duff. You can buy a tester on ebay about £3 to test the back lights if you see any dull patches that the tube to replace. A certain amount of skill is needed not for the faint hearted.

[rigeback]

Could be possible although from the back side the lamps seem to working okay, I did have the screen open at one point but never powered it up, will have to open her up again to verify, thanks for the info.