Toshiba 46sl417u main board issue

[shadetreetrader11]

Re: Toshiba 46sl417u main board issue

ic273 D2907 L2707 C2735 THEY ALL HAD 3.32VDC
IC290 D2910 L2900 C2907-2910 C2109 C2107 ALL HAD 5.77VDC
IC313 THE 100UF SMD CAP JUST BELOW IT WAS 4.98 VDC
C2705 C2707 C2708 FL174 ALL MEASURED 1.5VDC

[fzabkar]

Re: Toshiba 46sl417u main board issue

I have identified various voltage test points. Many will be duplicated because I can't be certain if you will make good contact with your probes.

You have identified the +3.3V, +5V, and +1.5V supplies. Could you now measure the voltages in the "regs3" and "regs4" attachments?

Here are various datasheets that may be useful to determine the voltage requirements:

MAX1993E, Maxim, PWM controller, step-down, 2V-28V input:
https://cdn.badcaps-static.com/pdfs/...a5c81d6a24.pdf

TPCA8030-H, Toshiba, N-channel FET (U-MOS V-H), 30V, 24A:

https://cdn.badcaps-static.com/pdfs/...bda575efeb.pdf

TAS5708, Texas Instruments, 20-W STEREO DIGITAL AUDIO POWER AMPLIFIER WITH EQ/DRC and FEEDBACK, 10V to 26V, 3.3 V Digital Supply:
https://cdn.badcaps-static.com/pdfs/...9d2a8d6a68.pdf

K9F4G08U0D, Samsung, 4G-bit NAND Flash Memory, 512M x 8bit, 3.3V:
https://cdn.badcaps-static.com/pdfs/...f2a7a8bf78.pdf

M24C64-W, 64-Kbit serial I²C bus EEPROM, 1.6V to 5.5V:
https://cdn.badcaps-static.com/pdfs/...d4a09a76ff.pdf

[shadetreetrader11]

Re: Toshiba 46sl417u main board issue

C1476 24.31V
C1403 24.31V
C3216 24.31V

C2915 5.14V
C1477 24.32V
C1448 24.32V

C2702 5.72V
L2701 5.72V
C2705 1.5V
FL174 1.5V
C2707 1.5V
C2708 1.5V

FL264 3.3V
FL263 3.3V
C2638 3.3V
C2640 .91V
C2615 .91V
R2607 .91V
C2743 2.49V
C2721 2.49V

C2744 5.14V
L2704 .91V
C2739 .91V

C2914 12.27V
C2915 5.14V


If I missed any let me know, Hope this helps

[fzabkar]

Re: Toshiba 46sl417u main board issue

Thanks. You've now found a +2.5V supply and what appear to be two 0.9V Vcore supplies. Therefore it appears that the SoC (the large chip under the heatsink) is a dual-core MCU. I don't understand why one of the Vcore regulators is "heavier" than the other, though. You might like to verify that there is no short circuit between the two cores by measuring the resistance between L2704 and R2607.

The next thing I would do would be to measure the same voltages again, once in standby mode (after switching on the AC supply), and again in run mode after pressing the power-on button on the remote or on the front panel. If some of the voltages are switched on by the remote, then this will prove that the SoC is alive.

[shadetreetrader11]

Re: Toshiba 46sl417u main board issue

resistance between L2704 AND R2607 IS 2.13 K OHMS
Remote has no control on tv. I tryed to plug the led driver board connector in correctly so the back light was hooked up and it was completely dead tv after that. So just letting you know that all readings are done with that plug half ways plugged in.

[fzabkar]

Re: Toshiba 46sl417u main board issue

ISTM that all the voltages are present. I'm not sure what you could do now other than scoping the crystal. Otherwise I'd be looking at IC603 (flash) or IC130 (EEPROM). Try heating or freezing them.

[NSkyLab]

Re: Toshiba 46sl417u main board issue

Hello everyone, I'm reviving this old topic and this is my first post here. I'm in need of your collective wisdom...

I got 55SL417U - same TV, bigger size. Similar sympthoms:
After I plug it in I see 3 blinks of a green led. In a few seconds the backlight comes on (sometimes it does not). And then nothing. A back-lit black screen, no sound. Can turn it on/off with sensor buttons or a remote.
I found several topics about this TV here and seems none managed to fix it. Replacing the MB is not an option as it is too expensive for such an old junk.

PSU is OK, I get stable 5, 12 and 24v. 24v has about 300mV pulsation, which I don't suspect as this is only there for the audio poweramp as far as I understand.

Onboard converters also seem good. I get the same readings as in this post above. There is no significant pulsation.

I can see activity on the flash and eeprom ICs for a few seconds. It seems like the SoC starts loading then it just hangs. There is nothing on LVDS.

I have not found an eeprom dump for it, tried erasing eeprom, didn't work.

Questions:
1. Vcore=0.9V. Does it seem ok? Soc is Broadcom BCM35230KFSB07G. I haven't found any info about it. I'd rather expect to see 1-1.25v there? Seems strange there are to Vcore lines both 0.9v...

2. This smd cap in the center of SoC on the bottom of the PCB (it's in paralled with Vcore I think) shows only 20ohm resistancу (i.e. whole Vcore bus). Is it ok for a SoC?


3. Is there a simple way to diagnose RAM, SoC (tried heating both, didn't work)?

4. Any other clues what can make it hang??