Service Forum

[dima]

Victor,
First of , thanks for the site. I also want to say that i have read every relevant post including the one on the r51.
MY R51( 15 inch screen) - 2883 uses the 4r80fCN chip.
I have built the simple interface an follow the procedure but have no luck.
the circuit is perfect but i get the " eeprom not available message"

I have double checked all wires with an Ohm meter, tried on different machines ( including desktops with higher com port voltages) and still the same issue.

This machine has a Power on password. Could this be the reason since in your intructions after pressing F1 user should be taken to the bios screen password message ( at which point sig cable is to be connected), but on my machine after the message " entering bios" and a pause i get the same Power on password ICON, it is almost like it never goes to the bios password!

Thinking that because of this issue the chip is not receiving power , i went ahead and build the power supply designated in the simple circuit PDF file. Soldered everything together, but still the same issue.

I am beginnnig to think that IBM did something to this machine model that is not the same as the previous models since i know that person on this forum reported success. The really strange thing is that in the maintanance manual for the R51 ( 15 inch screen version) it states that to
reset the power on password you can just take out the cmos battery, and start the machine witht the power supply. This is apparently one of the only thinkpads that has this workaround. And ofcourse this did not work as well.

Wondering whether i should solder the chip from the board, or build the more complicated interface? the challenge is fun but i am finally strating to get frustrated since it does not make any sense. I definetly double and triple checked all my connections.

One quick question is that i assume to power the chip you do not need to remove it from the motherboard? since I did not. I also messured the voltages at VCC* and PROT* and found them to be about 3volts during boot and password screen. I also removed the hard drive but i imagine this has no effect. Your help or any advice appreciated.

thanks
Dima

[victor]

[dima]

victor,
thanks for responding so quickly. It just struck me that i may have soldered the zener diodes in the wrong direction. I may not be able to try and fix this until next week. I will post some photos if this stil does not work.

Never worked with diodes before but your reference to ANODE made me think. this may be something that other people may benefit from since those of us with little electronics experience may solder the diodes in the wrong way.

will keep ou posted.

[dima]

victor---

thanks you , thank you ..thank you. fixed..amazing ..worked perfectly. i had one of the diodes backwards.
email me if you need me to send you a bios dump. i heard you guys can use them..

[victor]

I guess it was the diode on SCL line..

I would appreciate if you email the dump to our support email, thanks.