Electronics > Repair
Looking for Mettler Scale ROM backup
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gmac34:
in the same guide about removing IC 13 they mention its is a LM358, Dual, 30-V, 700-kHz operational amplifier


see page 122
jamarjan:
oh boy, what a fruitful thread it has become
I need to calmly read and understand your posts ;-)

fzabkar - of course I messed up with the rom dump - I mistakenly chose the wrong chip (I will delete my above post to avoid confusion)

gmac34 - I use a mercury lamp to erase the uv eprom
unfortunately my chip after zeroing is not programmable, although I tried different combinations of voltages and delay times (I checked datasheet for my chip - fujitsu)
i ordered some 27c256 chips both fujitsu and ti

i will report on progress
gmac34:
Then there is a good chance that a freshly flashed UVPROM is all you need
fzabkar:

--- Quote from: gmac34 on October 17, 2024, 09:38:49 am ---Then there is a good chance that a freshly flashed UVPROM is all you need

--- End quote ---

Its checksum was 0x00, so it looks good to me.

BTW, I use HxD (freeware hex editor).

https://mh-nexus.de/en/hxd/
gmac34:
Right, I thought you checked the EEPROMs, in that case maybe the UV one was good, but it’s odd that it doesn’t program. Doesn’t it program at all or do you just get some write here and there?
If it was my scale I would order a ram ic, I see it’s 3-4€ on eBay and if not a odd frequency the oscillator.
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