ThinkPad 770 won't post

[Bibin]

I found a 770 at a local thrift shop. It had no RAM, so I picked up a 256MB PC100 SO-DIMM and threw it in there. I also got the HDD caddy and stuck an IDE drive in it.

When I give it power, the fan runs, the numlock/capslock/etc keyboard indicators flash briefly, and it shows that it's trying (endlessly) to charge the battery. Nothing on the screen, or over VGA. any ideas? Common failure points?

[danikayser84]

Open it up and check the CMOS battery and main battery for leakage, it's a common issue with older batteries

Does the machine give any beeps or errors? Turn up the volume knob all the way in case it's down; also try reseating all internal connectors - also the 770 needs either EDO or PC66 RAM (but cannot be mixed) and a PC100 won't work

[rkawakami]

770 should be able to support PC100 SDRAM memory, most likely as long as it is low density. In other words, 16-chip 256MB module, 8-chip 128MB or 4-chip 64MB. Although the PSREF of the day says that you can mix SDRAM with 760-supported EDO, I would tend to avoid that situation.

[danikayser84]

I do suppose the 430TX chipset might balk at the 256MB stick though? (I know it has a hard limit of 256MB RAM last I recall, but I don't know if a 16 chip 256MB stick will work or not) I'd try a smaller stick if you have one (PC66 or low-density PC100/PC133), maybe the 770 doesn't like the 256MB you put in...

Also, I forgot to mention checking capacitors/etc. inside the computer and boards for any leakage/bulging/etc. (remember that these machines are about 20 years old); there's also a small sub-battery (which looks like a green/blue 3 button cells in a wrapper) for when you swap batteries that may potentially leak, check for that too

[kfzhu1229]

Unplug all RAM and boot. It has 32mb on board so no worries about that part

[Bibin]

No dice, with or without DIMMs. I grabbed a 66MHz SO-DIMM, it made no change.

I've opened it up, and I'm looking at the power board. Everything looks happy, the caps don't show the telltale leakage signs (or smells!). Any particular place to start?

EDIT - I took the whole thing apart, cleaned the sub-board connectors with isopropyl alcohol, and it's booting happily. Now I need to solve the faulty backlight (flashes on and off, until it gives up after about 20 seconds). I suspect capacitors in the inverter.

[kfzhu1229]

Try to replug everything? If that does not work, I guess you have to try to wash the motherboard then. I have a ThinkPad 770ED with a dead power board so I guess we could share parts if it is necessary so that WE can have at least ONE working unit.

[Bibin]

Well, at this point everything is working, although it doesn't seem to like my 40GB HDD (even when formatted elsewhere to <8GB), and the LCD backlight isn't working properly. I'm wondering if capacitors on the DC-DC board are at fault, actually.

Once I get a USB floppy diskette drive, I can get this thing booting DOS and poke around a little.

[kfzhu1229]

Your CCFL tube may have problems. If you want I have a spare 770ED working LCD from my dead computer for a cheap price

[Bibin]

I might be interested. Do you have an HDD that is confirmed to work with it? This one is rejecting all of the IDE ones I try.

[kfzhu1229]

My 770ED is dead so i cannot verify on there. However, i have a original 600 machine with the SAME processor to test and i have a bunch of old noisy but 100% non-defective IDE HDDs that work with that machine. I am sure it will work with yours since 600 is MORE picky than your machine. Also i have another special HDD caddy that only works to 700 series. If you need any of that or LCD let me know

[danikayser84]

Isn't there a limit of roughly 8.4GB on the 770/E (and others of same vintage, such as 600, 380XD/Z, 560X/Z)? Although I did get a 30GB working on the 380Z under Windows 2000, dunno if it was a newer BIOS or not; maybe try updating the BIOS (note: you will need a working battery and actual floppy drive to update the BIOS)

[kfzhu1229]

Well I got 40gb 5400rpm HDD from my T43 working on my 770ED but I think the system partition limit is 8.4GB though

[Bibin]

It looks like my DC-DC board may be at fault. No hard disks will spin up or get recognized. All tests pass, except the system board test, which points at the DC-DC board as being problematic. I replaced the two electrolytic capacitors near the top just now, but now I've ruptured one diode (marked S47L); the glue sticking the cap to the board pulled it right in two. Now the system won't even turn on, so I'll need to replace that first. Unfortunately, unless I ID this diode, or get a replacement DC-DC board (pricy...) then I can't really do anything with this system.