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Search: Posts Made By: tom66
Forum: Troubleshooting TVs and Video Sources Today, 02:36 AM
Replies: 22
Views: 230
Posted By tom66
Re: Emulating a main board CPU.

Be aware that these decompressors can be fooled if the file "looks" like something else.
Sometimes the firmware is encrypted or compressed in a proprietary manner.
Forum: Troubleshooting TVs and Video Sources Today, 01:07 AM
Replies: 22
Views: 230
Posted By tom66
Re: Emulating a main board CPU.

have you discovered if it is a SquashFS type filesystem or something else?
Forum: Troubleshooting TVs and Video Sources Yesterday, 02:36 AM
Replies: 22
Views: 230
Posted By tom66
Re: Emulating a main board CPU.

Almost certain it has some RAM, but not much more than a few hundred K.

It depends on what it needs to do, but image scaling can be done with just two/three video line memory (if you don't really...
Forum: Troubleshooting TVs and Video Sources Yesterday, 12:51 AM
Replies: 23
Views: 326
Posted By tom66
Re: PN50B450 - Turns on, Sound good, I think Backlight is good, No Picture

OK, looks good

With this setup still connected as is, please try to check the Vsc voltage on the Y-main.

Also, we need to check Vsch, for this, we will need to see a clear picture of around...
Forum: Troubleshooting TVs and Video Sources 09-20-2018, 02:22 AM
Replies: 32
Views: 396
Posted By tom66
Re: Simulating load on LED drivers.

The parallel MOSFETs are used in this application to dissipate as much power as possible in a small area.

You can use one big heatsunk MOSFET or hundreds of SMD MOSFETs, it depends on what you...
Forum: Troubleshooting TVs and Video Sources 09-20-2018, 01:54 AM
Replies: 32
Views: 396
Posted By tom66
Re: Simulating load on LED drivers.

ISET is a voltage input. So the pot would go across a voltage reference ideally. If you just use the battery as the reference then you may find the current changes as the battery slowly runs flat. ...
Forum: Troubleshooting TVs and Video Sources 09-20-2018, 01:35 AM
Replies: 22
Views: 230
Posted By tom66
Re: Emulating a main board CPU.

Well, that could indicate corrupted flash, but it is hard to know without fully analysing the firmware.
Forum: Troubleshooting TVs and Video Sources 09-20-2018, 12:40 AM
Replies: 271
Views: 6,799
Posted By tom66
Re: Just picked up a 55 inch LG 4k OLED for $50!

I think that is the panel. Since liquid dripped down around t-con you will want to check the ribbons on the panel have not been damaged. Clue here is that the whole panel lightly glows except for...
Forum: Troubleshooting TVs and Video Sources 09-20-2018, 12:38 AM
Replies: 32
Views: 396
Posted By tom66
Re: Simulating load on LED drivers.

Across the MOSFET between the drain and other end of the resistor.
You will want to modify that circuit of course.
Why don't you test it on the bench first. You should draw a schematic first.
Forum: Troubleshooting TVs and Video Sources 09-20-2018, 12:25 AM
Replies: 22
Views: 230
Posted By tom66
Re: Emulating a main board CPU.

Well, it looks like this CPU is too basic to run Linux, it has no RAM interface.
So the firmware will likely be an ELF blob, ARM or something similar.
It is perfectly normal to have blank spots in...
Forum: Troubleshooting TVs and Video Sources 09-19-2018, 02:20 PM
Replies: 32
Views: 396
Posted By tom66
Re: Simulating load on LED drivers.

Between the + and - of the LED driver output, where the LED string would normally go.
Forum: Troubleshooting TVs and Video Sources 09-19-2018, 02:19 PM
Replies: 22
Views: 230
Posted By tom66
Re: Emulating a main board CPU.

No

I have been reverse engineering a Samsung control board for a plasma TV out of interest, after a hardware hacking friend of mine was able to dump the firmware.

It took me about 8 hours to...
Forum: Troubleshooting TVs and Video Sources 09-18-2018, 06:53 AM
Replies: 10
Views: 95
Posted By tom66
Re: Samsung panel or ?

I would say definitely panel, the menu is affected by the stripes if you look carefully.
Forum: Troubleshooting TVs and Video Sources 09-18-2018, 06:26 AM
Replies: 23
Views: 326
Posted By tom66
Re: PN50B450 - Turns on, Sound good, I think Backlight is good, No Picture

OK, show me a picture of your control board with this set up, I need to check it is all correct.
Forum: Troubleshooting TVs and Video Sources 09-18-2018, 05:23 AM
Replies: 22
Views: 230
Posted By tom66
Re: Emulating a main board CPU.

I honestly think you'd have more luck if you were able to enable debugging or switch on a UART port.
You are not going to be able to emulate an SoC without significant confidential knowledge about...
Forum: Troubleshooting TVs and Video Sources 09-18-2018, 03:10 AM
Replies: 22
Views: 230
Posted By tom66
Re: Emulating a main board CPU.

Uh, good luck on that.

Look at a datasheet for even a basic microcontroller e.g. TM4C123GH6PM, I use this a lot in products I develop. It is an ARM Cortex-M4 with 32K of SRAM and 256K of Flash...
Forum: Troubleshooting TVs and Video Sources 09-18-2018, 03:07 AM
Replies: 32
Views: 396
Posted By tom66
Re: Simulating load on LED drivers.

That is why I suggested the circuit should be powered from a battery.
The circuit would respond quick enough to 100Hz PWM, possibly the feed forward cap around the op-amp would need tweaking but it...
Forum: Troubleshooting TVs and Video Sources 09-18-2018, 03:06 AM
Replies: 12
Views: 153
Posted By tom66
Re: Panasonic TX-L55ET60B

This would appear to confirm a bad panel.
Forum: Troubleshooting TVs and Video Sources 09-18-2018, 03:05 AM
Replies: 23
Views: 326
Posted By tom66
Re: PN50B450 - Turns on, Sound good, I think Backlight is good, No Picture

OK, 1st pic, bottom left 4 pin terminal block just near the connector with the grey wires.
Jumper pins 3 and 4 using a hard disk option jumper, alligator clip or bent paperclip or whatever works....
Forum: Troubleshooting TVs and Video Sources 09-17-2018, 02:08 AM
Replies: 23
Views: 326
Posted By tom66
Re: PN50B450 - Turns on, Sound good, I think Backlight is good, No Picture

ok, show me a pic of your control board, I think I know what is going on here.
Forum: Troubleshooting TVs and Video Sources 09-17-2018, 01:46 AM
Replies: 32
Views: 396
Posted By tom66
Re: Simulating load on LED drivers.

The logic would need its own power source but a 9V battery would likely work (just make sure to choose an opamp that works with a Vdd of 9V)

The rest of the power would naturally come from the LED...
Forum: Troubleshooting TVs and Video Sources 09-16-2018, 02:25 AM
Replies: 32
Views: 396
Posted By tom66
Re: Simulating load on LED drivers.

Yes you'd need a very big heatsink to do it, but it is possible.

Transistors are very good at dissipating heat. You can dissipate 200W in a standard TO-220 transistor with a large heatsink. ...
Forum: Troubleshooting TVs and Video Sources 09-15-2018, 03:32 PM
Replies: 32
Views: 396
Posted By tom66
Re: Simulating load on LED drivers.

Yes you could

If you want some ideas, see the schematics here
http://www.batteryshowdown.com/release-pack/Page001.pdf

(this was a project I designed about 6 years ago)

You'd need a much...
Forum: Troubleshooting TVs and Video Sources 09-15-2018, 02:11 PM
Replies: 12
Views: 153
Posted By tom66
Re: Panasonic TX-L55ET60B

Most likely it is not fixable but worth trying the test before condemning it
Forum: Troubleshooting TVs and Video Sources 09-15-2018, 07:50 AM
Replies: 12
Views: 153
Posted By tom66
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