Some handwritten notes for main board power circuit....

Okay, wow, I think I got it. It was a single bit flip in the SPI flash. Details below:

After confirming I could compute the CRC correctly, I thought most of the flash dump looked valid, so there must be only some very small corruption. Maybe it was a single bit. (I have seen this before on a cheap WRT54G router) So I wrote a script to brute-force every possible bit flip, and check CRC, it took 18 hours, and found one:

[CODE]
$ venv/bin/python3 spi_crc_brute.py samsung-un40h5003af.bin | tee spi_crc_brute.log
At 0x20000:
00000000: 80 00 02 00 00 00 20...

Ha! I was using flashrom 1.4.0.. but seems there have been changes. I built flashrom from Git (~v1.5.0-rc1), I think this brings better support for WP (write protect) features of the chip, and was able to program the flash (despite the "Protection mode: hardware"...)!

[CODE]
$ ./builddir/flashrom -p ft2232_spi:type=2232H,port=B,divisor=100 -c W25Q32FV --wp-status
flashrom v1.5.0-rc1 (git:v1.5.0-rc1) on Darwin 23.6.0 (arm64)
...
Protection range: start=0x00000000 length=0x00400000 (all)
Protection mode: hardware


$ ./builddir/flashrom...

In a few days I will get access to SMD soldering equipment and try to remove the SPI chip.

Until then, I spent some time understanding SPI flash dump file format, and comparing to the clean genuine firmware file downloaded from Samsung (T-MXL1JAUSC.bin). From [URL="https://github.com/neuschaefer/mstar-mboot/blob/962e8b8258378dded694883a9f9acb7058d34631/sboot/src/MSDecompress.c#L1346"]sboot/src/MSDecompress.c[/URL] we see there is a header at 0x20000 including a CRC32. The CRC32 algorithm seems unusual, not compatible with standard Python zlib.crc32. After more searching,...

I'm sorry, can you explain more? MStar is broken or SPI chip is broken?

I tried to erase SPI chip and write a firmware from Samsung website, for a very similar model (though not exactly the same). The firmwares have the same first 4 KB, many other similarities, maybe a chance to work.

But I cannot erase the flash chip:

[CODE]
$ flashrom -p ft2232_spi:type=2232H,port=B,divisor=100 -w T-MXL1JAUSC-4mb.bin
flashrom v1.3.0 on Darwin 23.6.0 (arm64)
flashrom is free software, get the source code at https://flashrom.org

Calibrating...

FYI I'm working on a TV which has the same CPU as this thread (MStar AEON / Eden). Here's my thread with some info: [URL]https://www.badcaps.net/forum/troubleshooting-hardware-devices-and-electronics-theory/troubleshooting-tvs-and-video-sources/3511810-samsung-un40h5003-boot-loop-every-~8-seconds[/URL]

I was able to decompress the firmware from mine, it's some kind of gzip (possibly modified) and yields a ~3.2 MB file. If you're still working on your project, and you want to send me your SPI dump, I can probably decompress it.

Would also appreciate if you could take a...

SPI flash dump attached.

HDMI to ground - all values in ohms: [TABLE="border: 1, cellpadding: 0, cellspacing: 0"]
[TR]
[TD] [/TD]
[TD] [/TD]
[TD]CN401_H1[/TD]
[TD]CN404_H2[/TD]
[/TR]
[TR]
[TD]1[/TD]
[TD]TMDS data2+[/TD]
[TD]30M[/TD]
[TD]33M[/TD]
[/TR]
[TR]
[TD]2[/TD]
[TD]TMDS data2 shield[/TD]
[TD]0[/TD]
[TD]0[/TD]
[/TR]
[TR]
[TD]3[/TD]
[TD]TMDS data2−[/TD]
...

Re: Enermax Tomahawk ETK450AWT PSU Repair

Thanks everyone for the kind words. (I neglected to enable e-mail notifications and only just noticed the replies)

Thanks also for the tips about capacitor quality. For a while I figured "replace all the caps" was some misguided effort rooted in myth - but having spotted such a failure myself first hand, I'm starting to understand the wisdom.

I'm not sure if I'll use the PSU (I've already ordered and installed a replacement) but all good to know anyway.

sam_sam_sam, glad you found the inf...

A few weeks ago my computer power supply (Enermax Tomahawk ETK450AWT) stopped working. Of course this led me down a reverse engineering and circuit debugging rabbit hole ;-) I also learned about capacitor Equivalent series resistance along the way, and wrote an article about it all. Here are some sneak peeks:







And the full article:
[url]https://github.com/cpatulea/src/blob/master/psu/enermax-etk450awt-repair.md#enermax-tomahawk-etk450awt-psu-repair[/url]

Enjoy!https://A few weeks ago my computer ...ermax Tomahawk...

Re: New Members - please post your introductions here

Hello, just registered here. Software developer by trade but recently venturing into electronics. Managed to build a 300 MHz one-transistor oscillator earlier this year ([url]https://foulab.org/projects/eigma/fan/[/url]) and recently repaired a 450 watt ATX power supply. You'll have to check my post in "Troubleshooting Power Supplies" for that one! :-)Re: New Members - please post your i...o electronics.