Thinkpads Forum

Glad you got things dissasembled. Sorry for never getting back to you about your e-mail, I just haven't had as much time on my hands as I'd like to have. I'd make sure that on the boards that come apart, there are no bent pins, no dust, no obstructions and that they snap together tightly. That's especially important on the CPU board.

I’ve been out of town for a few days but with your help have finally taken the unit completely apart and found NO obvious problems such as bent pins or electrical shorts. I did have a small part fall out after removing one of the boards (it looks something like a 1/4”x1/8” hinge, one half plastic & the other metal). I probably knocked it loose during disassembly and have no idea where it goes.

The Hardware Manual’s method to test for an undetermined problem is to remove the various devices, DIMM’s and batteries and then power it up to see if anything changed. Since the unit was dead, I don’t have a charged battery pack, only a working AC Power Supply.

Does anyone have a specific process I should follow to reassemble and check the unit out?

Can I check any voltage readings on the DC-DC card while it’s out by powering it with the AC Power Supply?

Any suggestions would be appreciated. Thanks.

I know this thread is long dead but couldn't resist an attempt at resurrecting it...

As it happens I have also got a 770Z with the same symptoms (no sign of life at all, no LEDs, nothing) and was curious as to whether you got yours fixed in the end or not?

I am about to try manually charging up the battery pack (outside the machine) to see if it the machine will start on battery power.

I have also looked at the power supply sub-board inside that laptop and after checking the fuses (about 10 of them, all SMD) I found one that appeared to be broken but alas, no change after replacing it.

Does anyone have any other suggestions?

Many thanks,

Lomax

Usually, it's the AC/DC circuitry that's the problem if your computer won't even light up. Depending on whether the AC/DC circuitry is separate from the mainboard or part of it, you'll either have to replace the power circuitry or the mainboard. You should be able to find some information in the hardware maintenance manual.

There has to be some DC/DC circuity on the power module but AC/DC conversion is done in the external power supply which is working fine.

Unfortunately the power module sub-assembly inside the laptop is all surface mount components on a multi layer PCB and it is beyond my abilities to trace a fault on something so small...

I guess the only option is to replace the whole power module, and even then there's no guarantee that the machine will work

Please, if anyone has experience of this fault in the 770 series Thinkpads, any information that you may have would be appreciated muchly - my 770Z has the 1280x1024 panel and I would love to get it running again!

Thanks,

Lomax

Success!

I have now replaced the DC/DC board in my 770X which has brought it back to life and it is now working perfectly! It is only a PII 300 but the SXGA (1280x1024) screen knocks the socks off most laptop screens I've seen!

I got my DC/DC card from eBay, http://cgi.ebay.de/ws/eBayISAPI.dll?Vie ... 8757193794 check it out, he has another 38 of them up for grabs...

Lomax