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The official 755 Upgrade and general information Topic

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Thinkpad4by3
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Re: The official 755 Upgrade and general information Topic

#61 Post by Thinkpad4by3 » Thu Jul 05, 2018 7:52 pm

1) What pieces are broken
2) a) How are you planning to use an ISO
B) note: most drives pre-1998 are picky about burned discs.
3) 755C's are very common. You'll find one.
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The efficiency of two screens equally sized with equal numbers if pixels are equal. The time spent by a 4:3 user complaining about 16:9 is proportional to the inefficiency working with a 16:9 display, therefore the amount of useful work extracted is equal.

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Re: The official 755 Upgrade and general information Topic

#62 Post by BillMorrow » Sat Jul 07, 2018 3:14 am

i'll look for the box.. it's downstairs with a metric ton of thinkpad stuff..
the iso is on my NAS..
my upload speed is 10mbps..
i suppose i can zip it up into several parts.. where to send it and can you receive it..? without some timeout or the like..? or use some sort of site that will receive your files.. it is 500mb MOL..
Bill Morrow, kept by parrots :parrot: & cockatoos
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She was not what you would call refined,
She was not what you would call unrefined,
She was the type of person who kept a parrot.
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NikNak
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Re: The official 755 Upgrade and general information Topic

#63 Post by NikNak » Mon Jul 09, 2018 8:24 pm

Thinkpad4by3 wrote:
Thu Jul 05, 2018 7:52 pm
1) What pieces are broken
2) a) How are you planning to use an ISO
B) note: most drives pre-1998 are picky about burned discs.
3) 755C's are very common. You'll find one.
The rear panel cover is missing (assuming it broke off, I hear that's common on these), the left lid latch is broke so the screen only latches on one side, and the left flip out foot on the bottom is missing.
Well, I was hoping to get a disc image of windows 95 and 98se so I can put them on a 3.5 floppy (for the 755c) and a cd (for my other thinkpad 2611) to reinstall it after I wipe the harddrive.
Do they have a problem with floppy's too?
and yes I'm keeping my eye out for one, thanks! :)

NikNak
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Re: The official 755 Upgrade and general information Topic

#64 Post by NikNak » Mon Jul 09, 2018 8:27 pm

BillMorrow wrote:
Sat Jul 07, 2018 3:14 am
i'll look for the box.. it's downstairs with a metric ton of thinkpad stuff..
the iso is on my NAS..
my upload speed is 10mbps..
i suppose i can zip it up into several parts.. where to send it and can you receive it..? without some timeout or the like..? or use some sort of site that will receive your files.. it is 500mb MOL..
That would be awesome thank you!
Could we use DropBox or Google Drive?

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Re: The official 755 Upgrade and general information Topic

#65 Post by BillMorrow » Sat Jul 28, 2018 3:13 am

you have to remind me to go digging..
Bill Morrow, kept by parrots :parrot: & cockatoos
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She was not what you would call refined,
She was not what you would call unrefined,
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ugzz
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Re: The official 755 Upgrade and general information Topic

#66 Post by ugzz » Thu Dec 13, 2018 12:48 am

Hey all, just signed up and this forum seems like a fantastic resource! Been a lurker since before i even purchased a 755, finally a snagged a 755cd in FANTASTIC shape at a fair price.

So mine came with Two hard drives, a 300MB and an 800. (not exact number, i think its a 320 and an 810 or something along those lines).
The larger of the two has the stock image, but it might be toast. It boots up, but i clicked on the midi player and all i got was "file corrupted" errors. But most other stuff did seem to open without issue.

So before i even messed with it too much, i wanted to back it up. I found my old 2.5" ide to USB adapter, pulled the drive, and was able to extract it from the caddy without too much hassle. However when i try to connect it to my system it detects as a 576GB IBM. I thought maybe it was windows 10 being screwy so i threw it on an older linux box, and same thing. I tried a different 2.5" ide adapter, and same again.
Given the failed detection, i also can't get anything to come up. Each system just tells me it needs formatted. I tried to run a linux clone tool that can clone an unformatted and unmounted drive, but it wanted me to free up 576GB to start. So i didn't even bother attempting.

Just wondering if anyone else has seen any behavior like this, or has has ideas or thoughts.
Thanks!

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Re: The official 755 Upgrade and general information Topic

#67 Post by BillMorrow » Thu Dec 13, 2018 1:29 am

just to let others know i have a box of about 5 or 6 755 series thinkpads..
i also have a pristine and very rare 755CDV..
if any interest in buying some or all, let me know..
Bill Morrow, kept by parrots :parrot: & cockatoos
Sysop - forum.thinkpads.com

*
She was not what you would call refined,
She was not what you would call unrefined,
She was the type of person who kept a parrot.
~~~Mark Twain~~~

ugzz
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Re: The official 755 Upgrade and general information Topic

#68 Post by ugzz » Thu Dec 13, 2018 8:00 pm

I should note that i had my info backwards. the 810MB drive had the factory image, the 320 had a custom w95 with seemingly all drivers installed on it. I was actually more interested in the "clean" w95 since the drivers were in and it was a small installation. But that's the drive that detects as 576GB and i can't access it anywhere. The 810MB boots great, mounts great, and i was able to image it no problem using 2.5 IDE -> 3.5 IDE -> USB adapters. I have the image saved and backed up and have no problem sharing, but I made it in Linux Mint with the built in "Disks" tool. It's an IMG format, and when double clicked in mint you simply get a "restore to" box and can choose a drive. Not sure if that's useful to anyone or not, but lmk. And If anyone has any ideas about my 320mb drive that detects as a 576GB get at me, Thanks!

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Re: The official 755 Upgrade and general information Topic

#69 Post by Thinkpad4by3 » Thu Dec 13, 2018 8:25 pm

ugzz wrote:
Thu Dec 13, 2018 8:00 pm
Not sure if that's useful to anyone or not, but lmk. And If anyone has any ideas about my 320mb drive that detects as a 576GB get at me, Thanks!
I tried my 755C's 340mb drive which won't mount but my 810MB toshiba drive will. I believe it has something to do with the 340 being a CHS drive and the 810 being an LBA drive.

How to mount a CHS drive though? I got no clue past a very old machine and laplink.
Thinkpad4by3's Law of the Universe.

The efficiency of two screens equally sized with equal numbers if pixels are equal. The time spent by a 4:3 user complaining about 16:9 is proportional to the inefficiency working with a 16:9 display, therefore the amount of useful work extracted is equal.

ugzz
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Re: The official 755 Upgrade and general information Topic

#70 Post by ugzz » Sat Dec 15, 2018 3:02 pm

Thinkpad4by3 wrote:
Thu Dec 13, 2018 8:25 pm
I tried my 755C's 340mb drive which won't mount but my 810MB toshiba drive will. I believe it has something to do with the 340 being a CHS drive and the 810 being an LBA drive.

How to mount a CHS drive though? I got no clue past a very old machine and laplink.
Yeah i think you nailed it. I did a bit more research and all i can find is a few places where someone has posted that it's possible to convert the lba detection to CHS, but from the data i'm seeing that's a task beyond my skillset. The few have done it don't seem to have posted any scripts or info beyond claiming it can be done.

-I'm not sure if this is anything, but i did just realize that fdisk lets you specify C H S for a drive. I read that CHS drives would have the CHS info printed on it, but these IBM 344MB drives don't. I'm not sure if that info is in the bios or anywhere else.. but i'm interested to at least poke a round a bit more.

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Re: The official 755 Upgrade and general information Topic

#71 Post by AntoniE » Sun Dec 23, 2018 4:52 pm

Hi ugzz,

I have a 810MB HD, but I do not seem to see any IDE->USB convertor as the connector on the disk (which actually seems to be in a plastic box) has beveled sides (like a trapezium) - as it fits the 755 motherboard connector. Is there some magic to connect to this 'strange' connector?

On your CHS / LBA / 320MB - 576GB (your really mean 'G' ?) - did you ever try to connect it with the USB (or direct) to a linux machine and run gparted on it?
I just used gparted to partition on an old ASUS machine a sick HD so that it became totally empty. Then with a dos boot diskette and FDISK /mbr you can get it to work under dos again (gparted loads grub in the master boot record (mbr) which fdisk /mbr takes away). Grub does not seem to like fat16 - as it boots into grub rescue.
You could also put the disk in the 755 and work with a bootable gparted diskette. (3.5") or cd.

I expect that in this CHS disk (cylinder/head/sector) the data in the mbr is interpreted as if it is a LBA - which gets your very strange results. 340MB with 512 byte blocks turns into 696'320 blocks. However, in the CHS addressing method ( https://en.wikipedia.org/wiki/Cylinder-head-sector ) S is pretty much always 63*512 bytes ( 32'256 bytes). On a 340MB disk the cylinders x heads should then together be 340*1024*1024/32246=11'056. Which would be 1024 cylinders and 10 heads. The 576GB disk would have 1'207'959'552 blocks. In binary: 0100 1000 0000 0000 0000 0000 0000 0000. 10 in binary is 1010, 1024 is 0100 0000 0000. It depends on how the control blocks in the mbr are arranged exactly, but I can understand that a CHS control block read as a LBA, especially if after the CHS control info there are some bytes with zero's that this can happen - approximately. If you do not need the data on the CHS disk, I would give up the free space and do a re-format. May-be even the dos fdisk /mbr helps already - as that will overwrite (part) of the master boot record ( the first 512 byte block or the first sector of the first head of the first cylinder). I do not know whether you can do a fdisk /mbr in windows.

Thanks - Antoni

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Re: The official 755 Upgrade and general information Topic

#72 Post by BillMorrow » Tue Jan 15, 2019 4:25 am

i see i've been here before..
NOTE:it is way past my bedtime so i'll be terse/brief..
the 755 hard drives were in a difficult to open caddy.. the pluig you see is not the HDD's..
i made up, 20+ years ago an adapter of some sort using the plug you can see..
i forgot what i made it for, maybe to interface a 3.5 inch drive to the 750 series thinkpads..
it was a LOT of work soldering.. :)
i'm ready to throw all that stuff OUT..
also have a few of those caddys.. maybe.. 750 series and 770 series..
to hook one of those old drives you need to get an old USB IDE (or whatever) adapter.. try amazon first.. i think bezos will be needing the business.. :)
i forgot all the rest of what i knew at that time..
BED is demanding my presence..
Bill Morrow, kept by parrots :parrot: & cockatoos
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She was not what you would call refined,
She was not what you would call unrefined,
She was the type of person who kept a parrot.
~~~Mark Twain~~~

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Re: The official 755 Upgrade and general information Topic

#73 Post by ugzz » Wed Apr 03, 2019 7:53 pm

It's been quite a while but I've been working on my 755cd again. I don't trust the hard drive to last, so i've been messing with the IDE to SD adapter you can snag on amazon. It seems like if you install DOS 6.22 onto it, it boots fine. But if you put just about anything else on it, or try to install windows from dos 6.22, it just goes into "invalid system disk". What the heck is going on here? How is it that the drive works fine with dos, but when you try and upgrade it the error goes to invalid system disk? Ii tested it by telling a VM to open the drive natively and it boots right into the windows installer, which is trying to do it's final steps. It's almost like it's somehow looking for dos, or specific boot blocks or something. But when using the native drive, this doesn't seem to be a problem. I tried dropping down to a 1gb SD thinking my 4gb one was too big, but same thing. I guess having dos booting is something and i can start digging for dos sound drivers, but i really wanted to get 95 up :P.

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Re: The official 755 Upgrade and general information Topic

#74 Post by MaxVCad » Sat Apr 13, 2019 11:34 pm

I acquired a ThinkPad 755CD from someone this week. He told me it was broken and described the symptoms but it was cheap enough I decided to take the chance.

The issue is that nothing shows up on the screen, not even BIOS. When i power it on, I can hear the HDD spin up, the HDD spindle operate for just a second, the CD drive seems to go through a boot process and I'm able to open the CD tray. When i hit the function key and one of its corresponding keys up top, I hear a beep that seems to come through the speakers.

I've soured the internet for information and have found a few posts. This actually seems to be a fairly common problem so I'm hoping one of you seasoned pros can share some of your unwritten knowledge with me.

So far I've tried booting the computer a bunch of times in a row. I've tried this fast, slow, waiting, not waiting etc etc. There's no other way I can do this. I read this somewhere as a possible solution. I've also tried hitting the reset button on the back panel with a pen tip and holding that down for 10 seconds while flipping the power button a few times.. Read that somewhere else. I've also tried opening the computer and removing the HDD, RAM, etc. The battery is already gone, I can see some mild corrosion on one of the connectors so it makes sense that it would have been removed and should have no effect on the computer's ability to operate (as long as it's plugged in). I also tried toggling the external monitor / display off function keys a bunch of times in case the issue was that it was setup to show on an external screen only.

The guy I bought this from says it worked fine for years and then one time, after having let it sit for about 6 months, stopped booting. He has no further info for me.

I see motherboards for sale on eBay, I'm wondering if that's the best next step. I'm not sure how to install one but I'm sure it can't be too hard.

What do you guys think? I really hope I can salvage this thing.

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Re: The official 755 Upgrade and general information Topic

#75 Post by kiki_hakone » Sun Apr 28, 2019 11:34 am

Your best bet would be to disassemble the laptop down to the system board and check if there are any "green" spots.

When these batteries leak, they often spew their guts onto the whole inside. That could be your problem - some bits of acid corroding crucial connections.

Also, check if the resume battery (the 3-cell green one) has leaked. They've leaked on my 755 and 3 of my 760s.
one year into retro thinkpadding
working: TFT 760EL, DSTN 760EL TFT 560E, chinese keyboard 380ED
undergoing restoration: TFT 755CD
broken/parts: 600 (dead? mobo), 760EL with a mosaicified TFT display, parts 560X

also a x220

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Re: The official 755 Upgrade and general information Topic

#76 Post by MaxVCad » Tue May 14, 2019 7:37 pm

Just to update.. I did get the 755CD working. The initial problem was a bad motherboard - I was able to find a seller on eBay with NOS ones so I bought one of those and it booted up.. Then the next day it failed again, this time the LCD. So I replaced that as well, buying one on eBay. At this point, the computer worked but had a bad mouse, so I had to order a new keyboard on eBay. With those 3 parts replaced, the computer seems to be operating normally. Thankfully all those parts were available for sale or I would've been pretty much out of luck.. Now I'm trying to get the battery working again. If anyone knows how to do this please let me know. I found a website that claims to be able to do this but so far no reply from them (https://www.batteryrefill.com/).

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Re: The official 755 Upgrade and general information Topic

#77 Post by kiki_hakone » Wed May 22, 2019 9:13 am

So... you pretty much replaced everything. Good for you nonetheless; enjoy your ThinkPad! :banana:

Now it's my turn, dear forum.

Recently acquired a 755CX in an absolutely perfect shape, barely used. Only had a leaked resume battery. Cleaned that up, and it booted right up. But, the keys near the TrackPoint as well as a few random keys are completely dead, same for the left TrackPoint button (the right one barely works).

Can you even get to the insides of the keyboard card to see what's up with it? I couldn't find any screws or latches or anything that would indicate it's able to be disassembled. And has anyone ever had a similar problem, is it fixable? Alternatively,
where can I get a replacement keyboard card in the EU?
one year into retro thinkpadding
working: TFT 760EL, DSTN 760EL TFT 560E, chinese keyboard 380ED
undergoing restoration: TFT 755CD
broken/parts: 600 (dead? mobo), 760EL with a mosaicified TFT display, parts 560X

also a x220

MaxVCad
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Re: The official 755 Upgrade and general information Topic

#78 Post by MaxVCad » Fri May 24, 2019 7:33 pm

This guy accepted my offer of $12 + free shipping and the keyboard was essentially like-new. Way better than the one I replaced, even the trackpoint was new and fuzzy. I had no idea they looked so different when they're new.

https://www.ebay.com/itm/84G6495-IBM-Co ... 2749.l2649

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Re: The official 755 Upgrade and general information Topic

#79 Post by kiki_hakone » Sun May 26, 2019 6:52 am

Envy you guys out there in the States; old ThinkPads are way more common where you live. If I was to order a replacement keyboard, most sellers in the US don't even ship to Europe :cry:
one year into retro thinkpadding
working: TFT 760EL, DSTN 760EL TFT 560E, chinese keyboard 380ED
undergoing restoration: TFT 755CD
broken/parts: 600 (dead? mobo), 760EL with a mosaicified TFT display, parts 560X

also a x220

goldeneagle
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Re: The official 755 Upgrade and general information Topic

#80 Post by goldeneagle » Mon Jul 22, 2019 6:34 pm

BillMorrow wrote:
Thu Dec 13, 2018 1:29 am
just to let others know i have a box of about 5 or 6 755 series thinkpads..
i also have a pristine and very rare 755CDV..
if any interest in buying some or all, let me know..
Nice to see I'm not the only one with a 755CDV. Mine is actually a combination of a CV and a CD (plus I have a regular 755CD).

Also, for the curious, I got Windows 2000 on my 755CD with a 4GB SiliconDrive II Compact Flash. I don't recommend it, because mwave doesn't work, along with the framebuffer and there are serial port conflicts. And good luck getting ThinkPad Utilities to work properly.
Historic ThinkPads owned:
300, 360C/CE/PE, 510CS, 560/E/Z, 600/E/X, 700C, 701C/CS, 720C, 730TE, 750C, 750P, 755C/CE/CX/CDV/CD, 760L, 760EL/XD, 765L
Newer ThinkPads owned:
P50, T480

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Re: The official 755 Upgrade and general information Topic

#81 Post by goldeneagle » Mon Jul 22, 2019 6:43 pm

MaxVCad wrote:
Tue May 14, 2019 7:37 pm
Just to update.. I did get the 755CD working. The initial problem was a bad motherboard - I was able to find a seller on eBay with NOS ones so I bought one of those and it booted up.. Then the next day it failed again, this time the LCD. So I replaced that as well, buying one on eBay. At this point, the computer worked but had a bad mouse, so I had to order a new keyboard on eBay. With those 3 parts replaced, the computer seems to be operating normally. Thankfully all those parts were available for sale or I would've been pretty much out of luck.. Now I'm trying to get the battery working again. If anyone knows how to do this please let me know. I found a website that claims to be able to do this but so far no reply from them (https://www.batteryrefill.com/).
A big F*** YOU to batteryrefill.com. Why? I used to work there. Crooks. They'll take your money and you'll never get anything. Technically, the site is open, but the business rebuilds Prius batteries now.

I can rebuild batteries for the 360, 755, 760, 560 and 600 (all models I've successfully rebuilt batteries for, anyways). Obviously, newer stuff gets trickier. The other problem is the prices quoted from batteryrefill.com. Obviously, I'd like to make a little profit (like $20-30). The cost of each HR-AUL cell (if you go the NiMH route) is about $4.25, plus shipping. Cheaper Chinese cells are around $3.50, obviously a little cheaper as the quantity goes up. For Lithium Ion, the cells used are Panasonic 17500's. I don't remember how much, but probably about $3.50-4.75 each. 770s and 600s use 18650s. I rebuilt a 770, but it doesn't work, so the pack could be dead.

And since this is a sticky technically...

I much prefer the 760-style NiMH packs. You hardly ever see any battery leakage. But the rounded corners style? I've maybe seen 2 without a crapload of leakage. I can't tell you why that is. Also, some of the 755CD models will let you use Lithium Ion batteries. The key is changing the battery terminals that connect to the DC-DC board. There's an extra pin, and a plastic key is shaved down. I don't know if the DC-DC board is any different, but from my experience, I don't think so (as I recently replaced a systemboard in my 755CD and also changed this battery connector as well). I believe all 755CV and CDV are capable of charging Lithium Ion batteries, including the 486DX4-100.

Lastly, all 755CE/CD/CV/CDV machines can be upgraded to a Pentium 75, simply by changing the processor, which is on the bottom of the system board. This adds some L2 cache, and you can now use non-parity memory; someone's selling $20 32MB DRAM cards on ebay, but they're incorrectly listed as KTM-TP750/32 equivalents. In actuality, they are KTM-TP360/32. But with a Pentium 75, you can use them now. Let's see, what else...


Large hard drives. I've been able to successfully use a 4GB CF card on my 755CD. 8GB doesn't work, and back in the late 90s/early 2000s, the largest I used on a 755 was a 6.4GB hard drive. It could be possible to use a 6GB Microdrive. You will NOT be able to boot up with DOS and a large SSD. Windows 95, Linux, NT, etc will boot up just fine.
Historic ThinkPads owned:
300, 360C/CE/PE, 510CS, 560/E/Z, 600/E/X, 700C, 701C/CS, 720C, 730TE, 750C, 750P, 755C/CE/CX/CDV/CD, 760L, 760EL/XD, 765L
Newer ThinkPads owned:
P50, T480

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Re: The official 755 Upgrade and general information Topic

#82 Post by pawelandrzejewski » Sun Aug 18, 2019 5:14 pm

I tried to upgrade bios in my 755CX. Of course couldn't due to battery (it is very leaked and will be hard to replace cells).

I have another idea - dissasembly all parts and programm bios directly on the programmer. Does anyone try this method (or have a photo of mobo)?

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Re: The official 755 Upgrade and general information Topic

#83 Post by BillMorrow » Sun Aug 18, 2019 11:30 pm

pawelandrzejewski wrote:
Sun Aug 18, 2019 5:14 pm
I tried to upgrade bios in my 755CX. Of course couldn't due to battery (it is very leaked and will be hard to replace cells).

I have another idea - dissasembly all parts and programm bios directly on the programmer. Does anyone try this method (or have a photo of mobo)?
welcome to the forum..
IMO unlikely to be successful..
too many unknowns i think.. :)
Bill Morrow, kept by parrots :parrot: & cockatoos
Sysop - forum.thinkpads.com

*
She was not what you would call refined,
She was not what you would call unrefined,
She was the type of person who kept a parrot.
~~~Mark Twain~~~

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Re: The official 755 Upgrade and general information Topic

#84 Post by pawelandrzejewski » Mon Aug 19, 2019 2:35 am

why do you suppose that no? On traditional PC I never use flash programs and programm directly on programmer.
I asked about photo to see what kind of IC holds the bios. It can be soldered to the board - no problem for me.

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Re: The official 755 Upgrade and general information Topic

#85 Post by pawelandrzejewski » Wed Sep 04, 2019 6:33 pm

I successfuly updated bios in my 755CX to the latest version. Dissasembled all parts, desoldered bios, flash with new version and solder again. So - IT IS POSSIBLE (but not easy job - bios is in TSOP flash ic) !

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Re: The official 755 Upgrade and general information Topic

#86 Post by Bondi » Wed Nov 20, 2019 8:11 am

kiki_hakone wrote:
Wed May 22, 2019 9:13 am
Recently acquired a 755CX in an absolutely perfect shape, barely used. Only had a leaked resume battery. Cleaned that up, and it booted right up. But, the keys near the TrackPoint as well as a few random keys are completely dead, same for the left TrackPoint button (the right one barely works).

Can you even get to the insides of the keyboard card to see what's up with it? I couldn't find any screws or latches or anything that would indicate it's able to be disassembled. And has anyone ever had a similar problem, is it fixable?
Well, I found the way do disassemble the keyboard. Hold it keys side down, ribbon cables facing to the front, on the left side, and slide the whole upper cover with your thumbs to the left.
Thinkpads: 330C, 360CE, 560, 755CD, 760LD, 760EL, A21p, A31p, X60s, X230

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Location: Toronto, Canada

Re: The official 755 Upgrade and general information Topic

#87 Post by pm2960 » Fri Jun 26, 2020 5:04 pm

ugzz wrote:
Wed Apr 03, 2019 7:53 pm
It's been quite a while but I've been working on my 755cd again. I don't trust the hard drive to last, so i've been messing with the IDE to SD adapter you can snag on amazon. It seems like if you install DOS 6.22 onto it, it boots fine........
hoping it worked out for you ugzz! ....did the SD adapter still need the hdd caddy in the 755 - or is there a way to modify the connector ...l was lucky to get a 755Cs recently - thanks to this forum! - and also a creaky hdd from ebay. replacing with a sd adapter sounds exciting...

ThinkIsaac
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Joined: Tue Jun 07, 2022 11:05 am
Location: Princeton, Minnesota

Re: The official 755 Upgrade and general information Topic

#88 Post by ThinkIsaac » Tue Jun 07, 2022 11:13 am

My CF adapter does not work on my 755cx, even with industrial cards, it boots from floppy fine.

evening_hunger
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Location: Normandy, France

Re: The official 755 Upgrade and general information Topic

#89 Post by evening_hunger » Sun Dec 04, 2022 5:06 pm

goldeneagle wrote:
Mon Jul 22, 2019 6:43 pm

I can rebuild batteries for the 360, 755, 760, 560 and 600 (all models I've successfully rebuilt batteries for, anyways). Obviously, newer stuff gets trickier. The other problem is the prices quoted from batteryrefill.com. Obviously, I'd like to make a little profit (like $20-30). The cost of each HR-AUL cell (if you go the NiMH route) is about $4.25, plus shipping. Cheaper Chinese cells are around $3.50, obviously a little cheaper as the quantity goes up. For Lithium Ion, the cells used are Panasonic 17500's. I don't remember how much, but probably about $3.50-4.75 each. 770s and 600s use 18650s. I rebuilt a 770, but it doesn't work, so the pack could be dead.
Sorry to resurrect this thread, do you know the cell type for the Ni-Mh rebuild? I was interested in doing it for my 755CE.
goldeneagle wrote:
Mon Jul 22, 2019 6:43 pm

Lastly, all 755CE/CD/CV/CDV machines can be upgraded to a Pentium 75, simply by changing the processor, which is on the bottom of the system board. This adds some L2 cache, and you can now use non-parity memory; someone's selling $20 32MB DRAM cards on ebay, but they're incorrectly listed as KTM-TP750/32 equivalents. In actuality, they are KTM-TP360/32. But with a Pentium 75, you can use them now. Let's see, what else...
Isn't Pentium 75 another socket and different core voltage?
T14amdR7-4750U/32GB/500gb.ssd/debian_testing (main driver)
X320/i7-2620M/8GB/256gb.ssd/FHD13.3''IPS/debian_testing (ex-main driver)
T30Pentium-M 4 1.8Ghz 512MB RAM - under restoration
X230/i5/8GB/500gb.hdd+256gb.m2ssd/IPS/debian_stable+win7
755CE, 486DX, approx 28MB RAM (Win95 JP)

goldeneagle
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Re: The official 755 Upgrade and general information Topic

#90 Post by goldeneagle » Mon Jul 24, 2023 3:53 am

evening_hunger wrote:
Sun Dec 04, 2022 5:06 pm
goldeneagle wrote:
Mon Jul 22, 2019 6:43 pm

I can rebuild batteries for the 360, 755, 760, 560 and 600 (all models I've successfully rebuilt batteries for, anyways). Obviously, newer stuff gets trickier. The other problem is the prices quoted from batteryrefill.com. Obviously, I'd like to make a little profit (like $20-30). The cost of each HR-AUL cell (if you go the NiMH route) is about $4.25, plus shipping. Cheaper Chinese cells are around $3.50, obviously a little cheaper as the quantity goes up. For Lithium Ion, the cells used are Panasonic 17500's. I don't remember how much, but probably about $3.50-4.75 each. 770s and 600s use 18650s. I rebuilt a 770, but it doesn't work, so the pack could be dead.
Sorry to resurrect this thread, do you know the cell type for the Ni-Mh rebuild? I was interested in doing it for my 755CE.
No worries. I've been more active on vcfed as of late. It's a Sanyo HR-AUL. I've used Tenergy and I do not recommend using cheap Chinese cells. I presume the internal discharge is high. In fact, I'm staring at what's left of one I did as an experiment. The cells were half the cost, but a few months of non-use and the cells were almost completely dead. IIRC, I couldn't even revive them. By comparison, I was able to revive Sanyo cells after more than a year of being very discharged, albeit with several cycles of charge/discharge.
goldeneagle wrote:
Mon Jul 22, 2019 6:43 pm

Lastly, all 755CE/CD/CV/CDV machines can be upgraded to a Pentium 75, simply by changing the processor, which is on the bottom of the system board. This adds some L2 cache, and you can now use non-parity memory; someone's selling $20 32MB DRAM cards on ebay, but they're incorrectly listed as KTM-TP750/32 equivalents. In actuality, they are KTM-TP360/32. But with a Pentium 75, you can use them now. Let's see, what else...
Isn't Pentium 75 another socket and different core voltage?
Not on the 755CE and above. Same exact socket. Some say you can uncheck parity memory from Easy Setup if you're still running a 486DX4-100, but I've never been successful doing this. There's definitely a noticeable speed improvement. In fact, I might only have two 755Cx class machines that are still 486's? I think one of them being my 755CDV. Everything else is a P75.

Now if only someone more well versed than I could get a drop-in ESS Audiodrive replacmenet for the crappy Mwave we're all plagued with...
Historic ThinkPads owned:
300, 360C/CE/PE, 510CS, 560/E/Z, 600/E/X, 700C, 701C/CS, 720C, 730TE, 750C, 750P, 755C/CE/CX/CDV/CD, 760L, 760EL/XD, 765L
Newer ThinkPads owned:
P50, T480

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