Samsung S27C450B BN41-01916A dump request

[piernov]

Hi,
Desperately looking for a firmware dump of this Samsung S27C450B.
Board has model numbers BN41-01916A and SC200/450 .


Attached are 2 firmware dumps:
W25X40_20191102_173736_S27C450B_BN41-01916A.BIN.zip : original dump. Doesn't turn on with this one, stuck at 60mA.

Монитор Samsung S22C200N (шасси bn41-01916a) Dump.zip : the only dump found on the web. Turns on, but seems to be corrupt as well and not compatible with the panel. If I try to switch to VGA input, it goes black and freezes (no response to buttons). Same if I plug a DVI input.



And 2 pictures, taken after flashing the dump found on the web:
IMG_20191102_181612.jpg : illustrates corrupt firmware, only menu I can access, shows corrupt text on bottom right
IMG_20191102_182130.jpg : illustrates possible panel incompatibility, working area for no signal box is 2/3rd of the panel and it gets repeated over.

[piernov]

Re: Samsung S27C450B BN41-01916A dump request

I think (and really hope) this one is finally fixed. What a nightmare.

Bought another mainboard since I couldn't find the firmware.
With "new" mainboard, it could turn on and work, but it'd usually power cycle and only turning on after a while.
Flashed "new" mainboard firmware onto old one, it was even worse and stopped turning on altogether at one point. Found a partial short to ground on the power rail connected to the SPI ROM and scaler IC, caused by the scaler IC.
Bought a scaler IC and put it on the original mainboard. No signs of life at all.
Bought yet another scaler IC and put it on the original mainboard. Same behaviour as the "new" mainboard.

At the very beginning I confirmed the mainboard was the problem by feeding it from the lab PSU, it was getting stuck or power cycling at low current as well. After flashing "corrupt" firmware it was still acting up but could turn on, reaching higher current consumption on the lab PSU.
I didn't check again the behaviour of the replacement mainboard on the lab PSU (I should have…), I only did that once I replaced scaler IC a second time on the original board, and this time the current consumption looked much more stable, going at around 1A when panel was turned on, so that's when I thought maybe the PSU was unstable under load.
At that point I was pretty convinced there was an issue with the PSU as well.

And at first I ignored it because I thought it was irrelevant, but the 5V rail wasn't really stable. Of course when I was measuring the rail without the panel or the backlight connected, it wasn't loading as much the rail, and of course when I connected them, it was at that point that it decided to suddenly turn on and work properly… what a nightmare to troubleshoot. But still, got it to act up while probing the rail, and indeed when it was cycling it was dropping just a bit below 5V (on the multimeter, on the oscilloscope maybe I could have seen it better). Replaced caps, checked feedback, replaced optocoupler… nothing did it, but of course everytime I changed something it'd randomly work so really hard to know if something fixed the problem. I started thinking it could be an issue in the feedback control in the primary side. I wanted to check a few things but there was glue in the way. So I removed it all, and at the same time I replaced thermal paste of the switching IC.
And it's been working perfectly fine for more than a week now.

Also at first I was a bit confused with the PSU, it has a "standby" mode where it sends only 3.8V on the 5V rail until it gets 3.3V on the I/O pin, then it sends 5.14V.
That standby mode is just a resistor in the voltage divider connected to the reference of the feedback circuit that gets bypassed by a transistor controlled by the I/O pin.

[piernov]

Re: Samsung S27C450B BN41-01916A dump request

Here is the firmware that should be working.