Sharp Aquos LC-32D40U - no image

[ahickman]

Good day! Just found an older LCD in the dump (Sharp LC-32D40U) and plugged it in. I get backlighting (blue screen) but see no images or sound. When I press the Menu button (or any other buttons excepting PWR), I get no response. The service manual is accessible http://elektrotanya.com/sharp_lc-32d.../download.html but I am unsure as to where to start troubleshooting. Seems like a T-con issue perhaps? I removed the T-con and visual looked it over. 3A fuse was good and no burned items. Suggestions of what to troubleshoot would be appreciated.

[retiredcaps]

Originally Posted by ahickman

Suggestions of what to troubleshoot would be appreciated.

Start with clear focused top down pictures of all your boards following my sig file below exactly. We want pictures in this composition.

http://www.badcaps.net/forum/showpos...94&postcount=1

[ahickman]

Right! Snapping a few pics now.

[ahickman]

Power supply, t-con, tuner and inverter. Scaler is on its way.

[retiredcaps]

Did you replace the caps with Panasonic caps or did you find it this way?

[ahickman]

Found it as-is.

[retiredcaps]

Originally Posted by ahickman

Found it as-is.

Lucky you. At least you don't have to recap it if/when it works.

[retiredcaps]

1) On the t-con board, check the VCC (5V) test point just by the F1 fuse.

2) Check to see if the voltages on the main board are okay.

3) I can't tell from the pictures, but see if the are any voltage regulators on the main board and see if they are within spec.

[retiredcaps]

Originally Posted by retiredcaps

3) I can't tell from the pictures, but see if the are any voltage regulators on the main board and see if they are within spec.

Did you follow up on this from post #8?

[ahickman]

Were it you, would you be confident that the t-con is the defective board?

[infringer]

Did you try unplugging and reseatting the cables? Oddly with bad audio and video I used to always go for the main board until my last TV it was the TCON but I wouldn't even get backlights ... So you are at least getting a BLON signal I assume. Anyhow I wish I could help further but this would be the quickest fix I am aware of indeed do do power tests if reseatting cables does not aid... Wish you luck.

[momaka]

There's a few test points on the t-con that you should check the voltage on:
VCC+5V, VDD, VGL, VGH, SDRAM_VDD, VLS, 3V, SSC_VDD, D-VDD, and S_VDD(?)
Check with respect to ground. Let me know what voltages you get.

[ahickman]

Originally Posted by momaka

There's a few test points on the t-con that you should check the voltage on:
VCC+5V, VDD, VGL, VGH, SDRAM_VDD, VLS, 3V, SSC_VDD, D-VDD, and S_VDD(?)
Check with respect to ground. Let me know what voltages you get.

I went ahead and orderd a replacement T-con from ShopJimmy. Plugged it up and all is good. Took the time to re-measure the voltages Momaka was interested in on the new card:

Vcc = 4.92v
VGL = -6.31 v

SDRAM_VDD = 2.96 v
VLS = 14.69 v
3V = 2.99 v
SSC_VDD = 2.96
D_VDD = 2.95

[retiredcaps]

What about U300, pin 13, the one that was 5% out?

[momaka]

Originally Posted by retiredcaps

What about U300, pin 13, the one that was 5% out?

Yes, now that we know that the old t-con was bad, it would indeed be interesting to troubleshoot the old t-con.

Unfortunately, this t-con is very different from others I have seen, so I have a hard time telling what U300 does. Normally, a chip like that is used to generate VDD, VGL, and VGH on other t-cons (those 3 voltages are standard, although other t-cons may give them different names such as AVDD, VEE, and VGE or VDD, VOFF, and VON). Perhaps that chip is used to generate the other voltages as well - if that's the case, then replacing U300 may solve the problem. Before doing that, though, I would say check every ceramic capacitor in the power section of the t-con for short circuit. That would be everything in the upper-right corner above the "Etrontech" RAM chips in this picture:
http://www.badcaps.net/forum/attachm...4&d=1341582445
If any of those capacitors read less than 50 Ohms, let me know which.

Also, if you see any bumps, holes, or other irregularities on top of any of the MOSFETs, they are likely bad. Your pictures are excellent, but such irregularities are hard to notice even with very very high quality images.

Sorry for the late reply.

[ahickman]

I have reseated the cables around the T-con and PS. No luck. Checking the voltages today.

[ahickman]

Ok, the T-con board is under the main shell, separate from the major boards and very difficult to get to while cables are connected. I measure the 32 pins along the connector CP7203 which extends into the T-con board. This 32 pin cable is serviced by the scaler board. Voltages are below. Pins that show 0.0V (GND) are skipped.

1. -
2. - 5.32
3. - 5.32
4. - 5.32
5. - 5.32
10. - 0.0
13. - 1.43
14. - 1.17
16. - 1.42
17. - 1.06
19. - 1.38
20. - 1.12
22. - 1.22
23. - 1.27
25. - 1.42
26. - 1.08
29. - 3.27

[ahickman]

CP506 coming directly off the main PS reads as follows:

1. 23.9 V
2. 23.9 V
3. 23.9 V
4. 23.9 V
5. 23.9 V
12. 3.3 V
13. 3.2 V

[electronicsurplus]

Originally Posted by ahickman

CP506 coming directly off the main PS reads as follows:

1. 23.9 V
2. 23.9 V
3. 23.9 V
4. 23.9 V
5. 23.9 V
12. 3.3 V
13. 3.2 V

Seems to be missing 5V Pon

[ahickman]

U300 - 16 pin chip, numbers as they appear:

3687V
1H05N08

Q302 - 8 pin chip, numbers as they appear:

4422
8E5519

U5 - 8 pin chip, numbers as they appear:

ATMEL602
25F512AN

Q303 - 6 pin chip, numbers as they appear:

D5CD IF

Q301 - 6 pin chip, numbers as they appear:

D13D 1L