0175/CRC1 once again, this time with a half solution

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Timoti · #1 Post by **Timoti** » Fri Oct 05, 2007 5:48 am

So i found the time to build the EEPROM reader circuit and made a dump from a supposedly working (it has power problems, not CRC1) T22 board.
You can find the software, the dump, and a few pics of Thinkpads mating at:

http://kaniak.kicks-[censored].net/other/thinkpad/0175.html

Problem is, the writer software is not freeware. So, if anybody has a licenced copy or a free one, please try out the dumpfile.
Or, if someone can send me the programming protocol of the Atmel chip, maybe i can write a very simple application.

phool@round · #2 Post by **phool@round** » Sat Oct 06, 2007 12:30 am

5,343.35 Hungarian Forint = $30 US Dollars.

Kind of expensive......

Have you tried to reflash the BIOS on that board after the error?

Timoti · #3 Post by **Timoti** » Sat Oct 06, 2007 3:55 am

Well, if i'd repair old Thinkpads for a living than 30 bucks would be okay, but just because of one board, that can be replaced for about 60, it's a bit too much...

Since these boards don't go beyond POST, much less boot, i'm not exactly sure how should i reflash it...

Kaervak · #4 Post by **Kaervak** » Sun Oct 07, 2007 4:59 pm

Not sure how useful this is, but opening up the bin file in a hex editor gives the machine type and serial number and you can edit the values. So it seems that you can take any eeprom dump, edit the type and serial number to your system and reflash the eeprom while keeping the system information intact. Seeing as how I don't have a copy of the eeprom writer either this is entirely speculation. I'm going to keep looking around and see if I can find an open source or freeware solution and let you guys know how things turn out.

BillP · #5 Post by **BillP** » Sun Oct 07, 2007 5:24 pm

Kaervak wrote:Not sure how useful this is, but opening up the bin file in a hex editor gives the machine type and serial number and you can edit the values. So it seems that you can take any eeprom dump, edit the type and serial number to your system and reflash the eeprom while keeping the system information intact. Seeing as how I don't have a copy of the eeprom writer either this is entirely speculation. I'm going to keep looking around and see if I can find an open source or freeware solution and let you guys know how things turn out.

I think editing the bin file would make the CRC data it contains invalid. Better to write the bin file as is and use the Hardware Maintenance Disk to edit the values that can't be updated in Easy Setup.

Kaervak · #6 Post by **Kaervak** » Sun Oct 07, 2007 6:21 pm

BillP wrote:I think editing the bin file would make the CRC data it contains invalid. Better to write the bin file as is and use the Hardware Maintenance Disk to edit the values that can't be updated in Easy Setup.

Ah that's right, I forgot about the HMD. Now I just need to get a valid T21 EEPROM dump and the writer software. Step one of three isn't bad.

Kaervak · #7 Post by **Kaervak** » Sun Oct 07, 2007 9:45 pm

Well, built the reader and dumped the EEPROM from my non posting T21 board. Interesting thing is, after looking up the seven digit type code online, it's actually a board from a T20. Ah well, not a whole lot of good it's doing me. Anyway here's the dump file if anyone wants to mess with it.

http://homepages.roadrunner.com/kaervak/t21nopost.bin

meh · #8 Post by **meh** » Sun Oct 14, 2007 1:53 pm

Ummh I think I just totally killed my T21. I accidentally dropped a glob of solder on the EEPROM pins and some solder is under them, making all the pins conduct

Should I sell it now?

Website · #9 Post by **tfflivemb2** » Sun Oct 14, 2007 3:47 pm

meh wrote:Ummh I think I just totally killed my T21. I accidentally dropped a glob of solder on the EEPROM pins and some solder is under them, making all the pins conduct

Should I sell it now?

As long as you don't connect power to it, you might be able to save it by getting a solder sucker and try removing all of the excess solder...it is going to take a good magnifying glass

Kaervak · #10 Post by **Kaervak** » Fri Oct 19, 2007 2:56 pm

Well, I found a way to fix the CRC1 without the writer software. It's not too terribly difficult, just takes time and patience and a little bit of insanity. You'll need the following:

A known working EEPROM chip from a T20-T22.
SMT soldering/desoldering gear. Or wrap a paperclip around the tip of your iron and use that. MacGyver for the win.
Floppy disk & UB2K Floppy drive with the latest BIOS for your machine.
Knowing that you may, in fact, destroy everything you're working on.

This worked for me, but it may not work for you, no guarantees. My T21 had a very old BIOS revision, which is why I think this worked.

Desolder your CRC1 EEPROM, solder on the good EEPROM and boot the system. That will fix the system but, the type number, UUID, serial & board serial won't be original.

Obviously you can stop here and have a working system again, but if you want the serial, type and UUID to match, read on.

Chances are since the system CRC1'd it has a very old BIOS revision. From version 1.10 on, the CRC issue has been fixed. So, get the latest BIOS from IBM, T21 BIOS: ftp://ftp.software.ibm.com/pc/pccbbs/mo ... sdkz34.exe and flash the BIOS. Reboot the system and verify the updated BIOS. Now power down the system, desolder the known good EEPROM and resolder the CRC1 EEPROM. Boot the machine and hit ESC when the splash screen comes up and watch the post screen. The new BIOS should have recalculated the EEPROM checksum and written the changes to it. You'll know if it worked because the CRC1 error will be gone.

Again, this worked for me because the system had a very old BIOS revision, 1.02 IIRC. This may not work for you and there is a risk of destroying both boards so proceed only if you're comfortable. I figured what the hell, one board doesn't post and this system is CRC1 so I don't have much to loose. Don't rush things, take your time with the soldering work, check all the connections make sure nothing is bridging and they're all solid solder joints.

That's pretty much it. The CRC1 T21 I have is working just fine. It took me about an hour and a half to do all the soldering work. I used a regualr iron and desoldering braid to remove the EEPROMs. Then I used solder paste and borrowed a friends heat gun (specifically designed for SMT work) to resolder them. For those of you that don't have a heat gun or don't know someone that does, I've heard that you can use your oven to heat the solder paste to the melting point. Be a little careful with that as I'm sure you can knock something else loose.

That's about it. If you're a tinkerer and don't mind the work involved with the soldering you can possibly fix the CRC1 error without the proprietary writing software. Also, I recommend doing an EEPROM dump of the good EEPROM and your CRC1 EEPROM before you go removing them from the boards just incase. You'll at least have some type of backup of the board details.

And no, I won't do this for anyone else for two big reasons. 1) The risk of destroying the board is fairly high. 2) I can't guarantee that it will work for every CRC1 error. However if anyone has questions, ask away and I'll help out as best I can.

aiches · #11 Post by **aiches** » Thu Feb 26, 2009 1:48 pm

Can anyone provide me with the file t21nopost.bin. The above links are dead.

Thank you aiches

0175/CRC1 once again, this time with a half solution

0175/CRC1 once again, this time with a half solution

Re: 0175/CRC1 once again, this time with a half solution

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