Author Topic: Looking for Mettler Scale ROM backup  (Read 4350 times)

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Offline gmac34Topic starter

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Looking for Mettler Scale ROM backup
« on: December 17, 2023, 05:17:41 pm »
Hi, I have a Mettler scale with a bad ROM, I tried to contact Mettler to see if they would share the 30y old ROM file with me but did not get an answer. 
If anyone has a copy, I think I need the "STANDARD SOFTWARE ME-34172" any version between 10.45 and 10.50 should work fine regardless of the model of the scale, this should be compatible with all scales from the era with the same cartridge ROM system.

Attached a picture of the cartridge, inside there is just a regular UVPROM
Thanks!
 

Offline fzabkar

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Re: Looking for Mettler Scale ROM backup
« Reply #1 on: December 17, 2023, 05:44:04 pm »
Can you upload a ROM dump? Or perhaps several ROM dumps? Perhaps it would be possible to perform a bitwise AND against all your dumps to create a hybrid ROM, assuming that errors are intermittent.
 

Offline jamarjan

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Re: Looking for Mettler Scale ROM backup
« Reply #2 on: October 16, 2024, 09:43:58 am »
Hi gmac34
attached dump of the ROM from my cassette
ME-34172 STANDARD V10.32
I hope it will help you fix your scale.

I myself am struggling with a PM4600 scale that is not working.
Probably as a result of dead low voltage dc capacitors, my NMC9346N chip zeroed out.
According to the service manual of the scale, you need to program it with a special cassette and an external keypad.
What is the model of your scale?
 

Offline gmac34Topic starter

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Re: Looking for Mettler Scale ROM backup
« Reply #3 on: October 16, 2024, 12:16:20 pm »
hi  jamarjan, thanks for the dump, I actually managed to get a newer version dumped as well, buying another scale...
I attached them here as well for posterity.

Regarding your problem, I believe you will have to contact a Mettler service center, try a few and see if one offers a reasonable price for the operation, I haven't manage to find copies of the service cassettes, but without those you will not be able to frost initialise the memory and tell the scale what it is but also input all the parameters for linearity and temperature compensation specific to your cell. I think they are written down in the real plate that you can remove to do the corner load adjustment.

I also have pm4600, so maybe I could dump that memory, but my linearity and temperature compensation data will not be correct for your scale.
I think I should dump that for posterity to keep my scale running, but that ic is not on a socket I'm a bit afraid of trying to get it off...
 
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Offline jamarjan

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Re: Looking for Mettler Scale ROM backup
« Reply #4 on: October 16, 2024, 12:37:13 pm »
Wow wow wow! What incredibly fascinating news!
Thank you for your response.
Desoldering the 8 pin ic is a relatively simple matter.
A tin extractor and a braid allowed me to desolder in a few minutes.
Later you can insert a 8 pin socket.
Would be very grateful to you if you decide to rip this ROM.
According to the service manual, the basic programming of the scale type just involves specifying the model and measurement range.
Calibration of the parameters you write about is a completely different matter and you need yet another cartridge and procedure.
The scale I am repairing is rescued from being scrapped and is actually for learning purposes.
Well, and that beautiful VFD (in my case it works like new)!
Also, once again, I would VERY much appreciate it if you would rip copy this internal IC at your leisure.
I am absolutely not in a hurry. It can be in a week or a month.
Thanks in advance!

attached a dump of my IC- blank except for the first 2 lines
« Last Edit: October 17, 2024, 09:37:51 am by jamarjan »
 

Offline jamarjan

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Re: Looking for Mettler Scale ROM backup
« Reply #5 on: October 16, 2024, 12:38:05 pm »
and by the way if you haven't done it yet - replace the electrolytic capacitors in the power supply
 

Offline gmac34Topic starter

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Re: Looking for Mettler Scale ROM backup
« Reply #6 on: October 16, 2024, 01:31:58 pm »
ok, here are the copies, I wasn't much afraid of removing them, I have a proper rework station for that, but rather heat and EEPROM do not go well together
anyway here you can find the backup from my PM4600 and from my PM3000

I think you could try to modify the rom to include the parameters from your scale, they should be saved inside the rom, attached you can see also the parameters from my scale, maybe you can find those numbers in the room and replace them with yours:

"The measuring cell parameters, balance/scale type, linearization and temperature compensation are contained in 21 5-7 digit numbers. These numbers are printed on the parameter sticker on the inside of the cover plate."
Let me know how it goes
 
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Offline fzabkar

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Re: Looking for Mettler Scale ROM backup
« Reply #7 on: October 16, 2024, 06:15:23 pm »
PM4600 dump:

Code: [Select]
Offset(h) 00   02   04   06   08   0A   0C   0E

00000000  02D9 C013 4650 FF00 DA00 1302 2000 4587
00000010  3143 1902 2941 090A 3100 3102 0A02 00A0
00000020  BC00 0031 6480 0201 0202 0002 F400 1B48
00000030  B542 0C16 3800 0000 0000 0000 0000 AEBA
00000040  0780 343C 04BA 1189 E505 056E F9BA 6AFF
00000050  FFEE 0258 7D00 FF1C 68C2 47FD 000C 0BBB
00000060  8B00 0005 E115 86FF 0766 0000 8843 C0E8
00000070  1400 DE28 BC1C 0004 0000 0000 0000 0000


These appear to be the 21 calibration parameters:

Code: [Select]
Offset(h) 00   02   04   06   08   0A   0C   0E

00000030                                     AEBA
00000040  0780 343C 04BA 1189 E505 056E F9BA 6AFF
00000050  FFEE 0258 7D00 FF1C 68C2 47FD 000C 0BBB
00000060  8B00 0005 E115 86FF

Code: [Select]
00: 306874 = 0x4AEBA - first parameter
...
20: 886527 = 0xD86FF - last parameter

It appears that the leading nibble is discarded ??? That is, 0x4AEBA is stored as 0xAEBA, and 0xD86FF is stored as 0x86FF.


Product ID = 874543.

Code: [Select]
Offset(h) 00   02   04   06   08   0A   0C   0E

00000000                                     4587
00000010  3143


Model name = PM4600

Code: [Select]
Offset(h) 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F

00000000              46

Model name = PM3000

Code: [Select]
Offset(h) 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F

00000000              30
 
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Offline fzabkar

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Re: Looking for Mettler Scale ROM backup
« Reply #8 on: October 16, 2024, 07:41:46 pm »
All the 32KB firmware dumps have an 8-bit checksum of 0x00. I don't know where the checksum byte is located, though.
 

Offline gmac34Topic starter

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Re: Looking for Mettler Scale ROM backup
« Reply #9 on: October 16, 2024, 08:03:41 pm »
thanks for you effort, fiddling with binaries is a bit above my pay grade. If it is of any help I have also dumped the EEPROM of a PM200 and attached parameters for all 3
 

Offline fzabkar

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Re: Looking for Mettler Scale ROM backup
« Reply #10 on: October 16, 2024, 09:06:43 pm »
21 calibration parameters

Code: [Select]
Offset(h) 00   02   04   06   08   0A   0C   0E

00000030                                     AEBA
00000040  0780 733C 04AE 02FF 3F05 055D FBA9 8EFF
00000050  FFF3 021A DC00 FF14 3C3E D6FD 000C F74B
00000060  CEFF 0000 072C 9A00

Product ID

Code: [Select]
Offset(h) 00   02   04   06   08   0A   0C   0E

00000000                                     4369
00000010  1937

Model number PM200

Code: [Select]
Offset(h) 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F

00000000              20
 

Offline jamarjan

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Re: Looking for Mettler Scale ROM backup
« Reply #11 on: October 17, 2024, 06:52:40 am »
Thanks for the response!
Unfortunately, it looks like my ROM wasn't damaged (it looks similar to yours).
After the swap, the scale still won't start.
For some reason, the microcontroller doesn't read the ROM's contents.
I have some activity on the NMC9346N read pin, but from what I can see on the oscilloscope, the instruction (read) doesn't seem to be correct.

All the voltages given in the service manual are within spec.
The microcontroller is warm but not hot.
The waveform on pin 1 uC doesn't appear every time the scale is started, and when it does, it has a strange waveform. I also have a not-so-nice XTAL2 waveform.
I'm running out of ideas on what else to check.
gmac34 I see that you know these scales quite well.
I, on the other hand, am an amateur hobbist with a very limited amount of electronic knowledge.
Maybe you have some tips for me?
Either way, you have a big beer from me ;-)
 

Offline gmac34Topic starter

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Re: Looking for Mettler Scale ROM backup
« Reply #12 on: October 17, 2024, 07:01:58 am »
Well, it seems your scale is not starting at all, in fact I think the scale is supposed to do some self checks at power up, and should give you an error in case the EEPROM is bad. As a first step I would suggest you try to burn the UVPROM with the 10.45 version above and make sure your is not corrupted. Do you have an UV eraser? a bad Cristal could also be a suspect.
 

Offline gmac34Topic starter

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Re: Looking for Mettler Scale ROM backup
« Reply #13 on: October 17, 2024, 07:05:15 am »
BTW, this was the behaviour of the scale I was trying to repair at the beginning of the tread, the UVPROM was corrupted, just a few stuck bits

I think we can safely assume the problem is in the digital section so either microcontroller, UVPROM, RAM or Cristal, I don't think IC1 can stop the thing starting

if you probed the Cristal correctly the waveform looks a bit wonky, so that could be easily replaced, next I would try the ram. I also assume that the analog part is working fine, do you see the beam move when you connect power? that part would work all the time, regardless of the state of the digital side
« Last Edit: October 17, 2024, 07:27:20 am by gmac34 »
 

Offline fzabkar

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Re: Looking for Mettler Scale ROM backup
« Reply #14 on: October 17, 2024, 07:32:15 am »
Can you upload the service manual or provide a link to it?
 

Offline gmac34Topic starter

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Re: Looking for Mettler Scale ROM backup
« Reply #15 on: October 17, 2024, 07:36:29 am »
Not a very useful SM
 

Offline fzabkar

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Re: Looking for Mettler Scale ROM backup
« Reply #16 on: October 17, 2024, 08:04:19 am »
I would check the data and address buses and the micro's reset pin.

Just out of curiosity, I notice that U4 (ME47820P) and U11/U13 (ME84202) appear to be Mettler custom parts. U4 has a crystal, so I'm wondering what it does.
 

Offline fzabkar

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Re: Looking for Mettler Scale ROM backup
« Reply #17 on: October 17, 2024, 08:24:45 am »
#jamarjan, your EEPROM is a 9346 (128 bytes), yet your dump is a 9306 (32 bytes). Why is that?
 

Offline gmac34Topic starter

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Re: Looking for Mettler Scale ROM backup
« Reply #18 on: October 17, 2024, 08:26:23 am »
The other Cristal should be for the integrating ADC, ME47820P should be part of it, but not a integrated ADC ic, you see nearby a LM 393 comparator, Mettler unfortunately used a lot of parts with custom codes, but non necessary custom parts.

given the position of U11 I would imagine  it si just a precision op amps supporting the voltage reference, U13 is on the signal path coming from the measuring resistor, I know it can be replaced with a daughter board to adjust linearity, and that is all in the analog domain before the ADC.
« Last Edit: October 17, 2024, 08:28:15 am by gmac34 »
 

Offline gmac34Topic starter

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Re: Looking for Mettler Scale ROM backup
« Reply #19 on: October 17, 2024, 08:33:49 am »
this is a service manual for a Sartorius scale of the same era, I believe they are quite similar in their implementation, of the analog PID on one side the ADC in the middle and the microcontroller on the other.
unfortunately this is the only schematics I have for this type of scales.

IC106 in this schematics should be the counterpart of U4, it's a gate array, and has it's own oscillator
 

Offline gmac34Topic starter

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Re: Looking for Mettler Scale ROM backup
« Reply #20 on: October 17, 2024, 08:46:58 am »
in the same guide about removing IC 13 they mention its is a LM358, Dual, 30-V, 700-kHz operational amplifier


see page 122
« Last Edit: October 17, 2024, 08:49:38 am by gmac34 »
 

Offline jamarjan

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Re: Looking for Mettler Scale ROM backup
« Reply #21 on: October 17, 2024, 09:36:48 am »
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
 

Offline gmac34Topic starter

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Re: Looking for Mettler Scale ROM backup
« Reply #22 on: October 17, 2024, 09:38:49 am »
Then there is a good chance that a freshly flashed UVPROM is all you need
 

Offline fzabkar

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Re: Looking for Mettler Scale ROM backup
« Reply #23 on: October 17, 2024, 10:17:01 am »
Then there is a good chance that a freshly flashed UVPROM is all you need

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

BTW, I use HxD (freeware hex editor).

https://mh-nexus.de/en/hxd/
 

Offline gmac34Topic starter

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Re: Looking for Mettler Scale ROM backup
« Reply #24 on: October 17, 2024, 10:25:30 am »
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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