Thinkpad 300 and Zenith 325L

[panips]

tl;dr They are NOT identical, but most of their parts are swappable

I believe my Thinkpad 300 was an NOS. It's sealed, but the screen is really bad due to its age. I just got no time working on it for 1 year, until I finished my work on 700c and 720c.
Since I heard a lot of negative feedbacks on the thinkpad 300, I managed to get an (almost) working Zenith Data System 325L before starting to restore it, thinking that at least I can transplant everything to that thinkpad. So I spent quite a bit time repairing the 325L and make it work, and then opened my box and took out the brand new 300. It's not as bad as I was thinking. In fact it boots, although it is not stable and the VGA output seems buggy. I feel like the random characters it outputs to the external monitor might be caused by power supply of its mobo, so a full recap seems to be necessary before any further debugging. BTW, this is a really old laptop, you may need a monitor supporting 15/30kHz.

There is a lid to the top right of the keyboard, under which there are slots for memory and 80387sl. Slide it to the right and lift from its right end first.


On the back side, after removing the battery, there are 5 screws.


and another 3 screws to secure the top case


carefully lift up the top case and LCD assemble, there are two cables, 1 flat cable is the power/status indicator cable, another on under the hinge is for the LCD.


by removing the LCD assemble, you can see 2 flat ribbon cable and one screw to secure the keyboard


And 4 screws (red) for the System and I/O board. Don't forget another 2 (yellow) on the I/O panel


Here is the view from the back:


The system board is connected to another power/ south bridge(?) board by 2 connectors, lift up it carefully. Here is how the connectors look like:


rest of the parts are easy, 3 screws for the HDD and 1 screw for the FDD. Lift up the HDD and disconnect it, for FDD, slide it to the left and lift it up to remove it.


Two other cables for the CMOS battery and speaker. I'll talk about the battery later but remove it as soon as possible


Five more spacers and you can take out everything


Recap is trivial so I'd share some experience on battery and lcd later.

[panips]

With some easy fix, I could get the 300 working now. I then used a CF card and boot it to MSDOS. It looks like the lcd and vga output are all good.

now, remove the four screws here


be careful, DO NOT APPLY ANY IPA here! It damages the surface coating.


the LCD cover is extremely difficult to remove, you should pull left and right out (with top left and top right corner), and then bottom part, and finally the top part by pulling down the whole piece. I here marked some tricky points but you still need to try and figure it out yourself.




now you'll see two boards, left one is for the ccfl and right one is for the contrast. I marked most of the capacitors here, and you may click the image to see more details




Recapping is boring...
I did the same thing on my 300 and Zenith 325l, however, both ccfl did not work after recapping. I carefully examined and checked all component but still cannot get it work. Eventually, I had to add a fuse here so it works again. So if you got the same problem, you may do the same.

for the lcd itself, it's a STN monochrome display. The back/rare polarized film seems to be a normal one, but the front one is a film with optical compensation. Try finding a seller in HK or CN, ask for samples and find out a proper one. It's almost impossible to make it fully fit, but you can still find some films that make it look ok.

[solidpro]

I feel your pain my friend. Only yesterday I saw my large laptop bag on the shelf which contains my own 'restored' 300 and 325L has half-brothers.

I vaguely remember going through the same journey as you, although as I recall, my STN screen responded well to the fresh capacitors.

I am curious to take my two back out again but I'm concerned about being sucked into trying to repair whatever has failed since the last time it went away.

Good working finding working polarisers. They're a pain to match up on these old displays. Keeping the 300 going is certainly is a pursuit you follow with your heart and not your head! If I do pull mine back out, I'll post back some of my pics and observations.

Off topic - your collection is very close to matching mine. The 130 was a let down, eh? Is your 220 working? I have 3, in pieces and not working. Same for the 530. I might have a 730TE for sale soon. I'm also forever searching for a 320, but I know if one ever shows, it's going to be a mess....

[astral]

Could you post some photos of the 325L motherboard? I see the 300 uses the Cirrus GD6410 video chip, while my records on the 325L says it used the WD90C24 - I'm curious if the source I had on the 325L was wrong.

[panips]

Could you post some photos of the 325L motherboard? I see the 300 uses the Cirrus GD6410 video chip, while my records on the 325L says it used the WD90C24 - I'm curious if the source I had on the 325L was wrong.

Yes, I'm going to talk about the differences between 325l and 300. In short, 325L uses Cirrus GD6410, too. And this is how it looks like:


or, to be more clear


And, I forgot to post another picture. The ccfl driver board has an empty slot with "FU1" label, so I put a 2A fuse here and I don't know why it just fixed the problem.

[panips]

The keyboard, mainboard with power and south bridge (mobo B), lcd with driver/inverter boards, fdd, hdd, speaker, cmos battery and main battery in Zenith 325L and ThinkPad 300 are the same. That is, they are swappable. I tested them and all worked well. The different parts include lcd front bezel, keyboard bezel/upper case, and the system board with I/O (mobo A), and housing.

Start from the keyboard bezel, specifically, 325L has 2 screws instead of 3. The other screw is to secure the keyboard while ThinkPad 300 has that applied from the upper case.


325L has more fancy led status indicator and some other indicators like battery etc., most of them are connected to mobo A. The power button (leftmost one) is connected to mobo B. Interesting enough, mobo B in ThinkPad 300 also provide such connector but not used.


325L has a 20pin flat cable connected to the status indicator, while ThinkPad 300 has a 25pin one. From the back of the 325L board, you can see it HAS 25 pinout, so theoretically you CAN use the 325L board on a 300, but you need to replace the connector with a 25pin one.


the upper two connectors are for 325L only, the pinouts are also there in 300.
in short, for all inner parts, 325 and 300 are the same expect the connectors.

For the firmware/bios, they are pretty similar. The only difference I can tell is the message shown on the screen when you press the power button. 300 asks for enter/esc to confirm/cancel, while 325L uses Y and N keys. I don't know if it is because of the bios version cuz I figure out my 300 and zenith 325lp (yes, another 325 with dstn) are the same. I did not tear down my 325lp but still wondered if it has the same mobo A with a different jumper for the color display.

[solidpro]

Memory swappable?

[panips]

1) Memory
According to IBM manual, there are 2 types of memory stick, 2M and 8M. They are swappable on 300 and 325L (as well as some other variants like 325lc, 325lp, 300c, and maybe 320l etc.)

Left one is the 8M stick, 512k x 16 chips on board, 2 slots size. Right one is the 2M one. 512k x 4 chip and 1 slot size. All chips look like the same, which is 5v fast page memory with 1Mx4bit 80ns.




300/325L has 2M on board memory and can be extended to 12M max (=2M+8M+2M, 3 slots, 2 slots for 8M stick and 1 slot for another 2M stick)

2) CMOS battery
An 4.8v battery is used. You can rebuild it by using (the same) 4 gumstick F6 battery. But, the F6 size are rare and pricey, you may search for 2/3 F6 or 3/5 F6 size ones instead.
Be careful, you may see a lot of 7/5 F6 size gumstick batteries for sale used in a walkman, they do NOT fit. And, please use a spot welder to rebuild the battery.




3) Port replicator
Since their mobo are almost the same, I assume the port replicator is also compatible.


4) On-board Ethernet
Never saw it. Guess it's swappable.

5) [more?]

Some more pictures if you're interested in what's in the original box.

[astral]

It's good to know what cells that flat pack battery uses - I will make a note of that. I suspected at least some of the boards inside would be compatible.

[panips]

It's good to know what cells that flat pack battery uses - I will make a note of that. I suspected at least some of the boards inside would be compatible.

Yes...they are compatible, or at least you can make it (physically) compatible with little effort.
There are 300c and Zenith 325lc, and I feel safe to say they are the same case just like 300 and 325l. Moreover, I assume you can even use some 320l to fix your 300.
I just spent little bit more time on the 300 last week, trying to revive the old HDD and in fact it works again. I opened it and moved/greased the head, and it seems the old 80M HDD is back. But, after 30+ years this apparently cannot work like a brand new one, I formatted it and there were several bad sectors, making it ~79M after fixing.
For new old stock HDD, my suggestion is to stay away from them. It would be almost 100% chance that it gets stuck and cannot be fixed without opening the case. For even older HDD, especially some old CHS ones, some unknown material were used to seal the seam, and the sealant looks like tars when it degraded. The worst case is that the disk is messed up by all these tar-looking, degraded sealant. I tried to clean one old 340MB HDD, but (likely) failed after spending 5 hours and two bottles of IPA.

[solidpro]

Just as a reminder, I have done a cosmetic comparison of the 300 and 425 if you follow this link: https://ret.rocks/index.php/ibm/300-ser ... ies-review.

[ThinkDan]

I pity the poor sods who looked at IBM's adverts and thought "Hey, that new ThinkPad notebook is really cool and getting great reviews, I'll buy the cheaper one of the two..."



"Every detail says IBM, except the price."

[astral]

I don't quite the hate for the 300? Is the 700/700C a far better machine? Yes, absolutely. Is the 300 a terrible laptop? I certainly don't think so. It was the cheap model, and so you didn't get the trackpoint or a 486. Unless the different plastics feel 5 times worse than the Zenith version, I'd say the build quality is very good (I only own a Z-Note 425Lnc, the 486 version of the 325Lc). The 425Lnc is personally one of my favorite 486 laptops, I think they're built far better, and are much nicer to disassemble than the competing Compaq LTE Lite series laptops that I've also dealt with.

Obviously, reliability is a problem today due to the leaking capacitors, but good luck keeping a 700C from destroying itself when you use the hinges, and good luck if your 700C's ESDI drive kicks the bucket - they're both problematic machines.

I just feel like a lot of people hear "IBM didn't build them" and immediately run for the hills. The Zenith platform they're based on is a nice one! It's quite different from a "real" ThinkPad, but they're neat in their own way.

[ThinkDan]

I don't quite the hate for the 300? Is the 700/700C a far better machine? Yes, absolutely. Is the 300 a terrible laptop? I certainly don't think so. It was the cheap model, and so you didn't get the trackpoint or a 486.

I hear your defence, let me put the case for the prosecution

I've owned one. The 300 is a fraud; every key innovation that made the 700C an award winner is lost. It didn't have the keyboard, the TrackPoint, the largest available colour TFT screen, the modular design, the docking station option, the crisp design. All those nice touches that business users who could justify a $4000 laptop in 1992 wanted. It's not even black, and what paint it has rubs off for fun. The 700C was such a success that IBM could not manufacture them fast enough to satisfy demand.



The 300 is simply a middling laptop re-clothed to mimic an IBM model. It wasn't a good laptop at the time - IBM had appalling DOA rates for them, and high warranty costs, to the point that in Greenock and Raleigh shipments were opened, tested, and reworked before shipping onwards to customers. Perhaps there was some special crapness in the 300 because it was built down to a (manufacturing) cost significantly less than Zenith's own equivalent model? It's speculation.

Quite what IBM thought they were doing with the Zenith 300 I do not know. I would firmly argue that an N33 / N51 is a better notebook than the 300 ever was, and an upgraded N33 / N51 would have made a much better entry-level ThinkPad in terms of features, reliability, and fit with the ThinkPad brand. Actually, in Japan they did just that, with the ThinkPad 320.



To criticise the 700C for capacitor failure is rather unfair, as it is not exactly a problem unique to the 700. So much across the field of electronics from the early 1990's suffers from capacitor failure that re-capping is a common repair route for any old TV, audio, computers, ...

The hinges, yes, they were a design fault, although they have worsened over time and with plastic cases ageing machines do self destruct. The subsequent hinge design on the 360/750/755/760 models still stand up well today - with those machines having arguably had a longer service life than the 700/720 since they could be usefully used through the Win95 / 98 / NT4 era. I've found that an IKEA Samla 45l crate is the perfect size to safely store and stack a 700/720 in the open position, largely sidestepping the hinge fault.

[astral]

And now it is time for cross-examination

Very true - the ThinkPad 300 lacks the innovation of the $4000 700C. It also cost half that, and compared just fine to other laptops from the time. I don't think it's fair to compare a budget laptop to the top-of-the-line, rather, I'd compare it to other cheaper laptops of its day. In that context, it's perfectly fine. An already proven design (being based on the Zenith), with a decent keyboard, excellent support for internal networking, and middling performance.

I definitely think it's a far better machine than the PS/2 Note line was - those universally felt terrible. The PS/Note hinges are literally the worst and cheapest feeling things I have ever felt in a laptop. Their design leads to them having a great deal of spring tension that makes it feel awful to operate. The TP300 would be a major step up in build quality from those. I'd say the whole PS/Note line has aged far worse than the 300, only because those need recapping, and major reinforcement to the terribly designed hinge mounts. The 300 hinges seem to be mostly fine, just like the Zenith versions are.

On the DOA rates, that is the main problem of course. I'm making the argument that a working ThinkPad 300 is a perfectly fine, if as functionally uninteresting laptop. If the issue is DOA rather than "design flaw that caused the motherboards to die after a year of use", then you can safely assume that most surviving examples today are going to be "good" units that will work fine, when recapped.

And speaking of caps - I only brought that up because you see a lot more people using the TP300's cap problems against it than you do for other models. Both the 300 and 700 needs caps done at this point, and that's fine an expected. As you've said, it's a widespread problem. I just see people singling out the 300 due to this, which I feel is unfair.

So - is the 300 a great laptop? No. Is it any more unremarkable and "bad" as any other budget laptop from 1992? No.
At least, that's my opinion

[ThinkDan]

All good stuff, nice to have a constructive difference of opinion

My experience with the PS/2 Note hinges has been that they are reliable - still operate, open, hold screen at an angle - if a little worn now. This holds true for the early PS/55 Note, 2x N33 and N51 that I have. What definitely do fail is the ThinkPad 350 / PS Note 425 hinges, which appear to be of the same 'seized hinges / brittle case' generation as the 700/720.

The naming of these generations is confusing. (I just had to correct a typo above!) PS/55 Note, PS/2 Note, PS/Note being identical or very different machines, some of which then were made by 3rd parties. Almost makes the non-linear / non-chronological ThinkPad model numbering seem logical

When I was looking for a power supply for my 300 a few years back, the Zenith 325 was still common-ish in the UK - in that there would be one or two on ebay a month - and I got a Zenith branded power supply quickly and cheaply. Many of the surviving Zeniths had been BT machines - the UK phone company - with some sellers saying they'd been issued them as BT engineers. Clearly quite a few survived despite the rigours of 'real' use in the field. The only way I can square this is to speculate that the ThinkPad 300 was in some way a cost reduced version of the Zenith 325, even though there is clear interchangeability of major internal components.

[solidpro]

I pity the poor sods who looked at IBM's adverts and thought "Hey, that new ThinkPad notebook is really cool and getting great reviews, I'll buy the cheaper one of the two..."

Funny how those two quotes on that second page, specifically about the Trackpoint II and the full colour display are completely null and void with regards to the 'other' thinkpad (the 300) on the page.

[solidpro]

I think we can all agree that the 300 is comparivitely not-that-bad in the context what else was available for around £2000 at the time. I think we can also agree it should never have been branded as a thinkpad because it clearly isn't.

Suspect IBM had outsourced stuff to Zenith a few times and felt they needed to plug a gap and went with the route of less friction by asking Zenith to come up with something.

I am always really interested in preserving these quirky dead ends in the Thinkpad roadmap, proabably in the same way freakshows used to sell a lot of tickets. I also find it really interesting that IBM were selling the Zenith-made 300, the PS/Note N33SX (or 320), the 700C and the 700T all approximately at the same time and all completely different portable PCs. Like putting £1 on all horses, you're definitely going to be able to proclaim picking the winner.

It somewhat makes sense that BT used Zenith because I have a faint memory that Zenith stuff was made in the UK. At that point ex-publicly owned companies were steered towards 'buying british' which was at least possible back then. You see Apricot, Bull, ICL along with a few others I forget all having British company asset tags stamped on them, along with Zenith all showing up as obvious shoe-ins against the probably-better, probably-more-reliable, probably-more-advanced Far Eastern competitor. Having said that about BT, their next field laptop was the Panasonic Toughbook CF-27 and CF-28, which was Japanese inside and out. Not very British or ergonimic but very very tough.

[astral]

The Z-Note 386 and 486 laptops were actually made in Japan, presumably by Sanyo since they're full of Sanyo parts.

[astral]

All good stuff, nice to have a constructive difference of opinion

My experience with the PS/2 Note hinges has been that they are reliable - still operate, open, hold screen at an angle - if a little worn now. This holds true for the early PS/55 Note, 2x N33 and N51 that I have. What definitely do fail is the ThinkPad 350 / PS Note 425 hinges, which appear to be of the same 'seized hinges / brittle case' generation as the 700/720.

The naming of these generations is confusing. (I just had to correct a typo above!) PS/55 Note, PS/2 Note, PS/Note being identical or very different machines, some of which then were made by 3rd parties. Almost makes the non-linear / non-chronological ThinkPad model numbering seem logical

If the hinges in the earlier PS/2 Note laptops are better then that's good to hear. Maybe I'll give one of them a look someday.
There was yet another model not yet mentioned, the Type 2141, or simply "IBM PS/Note". It predated the 425 but has about the same case design (in a gray color instead of black). Same bad hinges. I think the PS/2 Note models were actually microchannel based?

To my knowledge, all of PS/Note line was made by IBM in-house, except for the N45sl, which was made by Zenith.

[solidpro]

except for the N45sl, which was made by Zenith

...which is a bit like, but not the same as the 300 / 325L... viewtopic.php?t=135136

[panips]

OK, just got a Zenith 325lc, which should be the same as 300c, from eBay. It works well with some quick fix of failed diodes and capacitors.



I realize why @astral asked about the video card info. In fact, it's Cirrus GD6410 with 256KB, so only 16 colors supported at 640x480. The full function specs can be found here https://theretroweb.com/chip/documentat ... 253612.pdf

Assuming that 300c and 325lc are identical, the differences between ThinkPad 300 and 300c were few. Both top mobo are identical/swappable, and the bottom mobo have some different on jumping wires.




typical Japanese style jumping wires which can be found in almost every (90s) laptops made in Japan.


No idea why they are different but I guess it is because of the LCD display. 300c has one extra cable to the mobo (3/6 pins) while 300 has not. And, Zenith 325lp is different, it has a 8pin connector here, and the layout is different than 325l and 325lc. I was thinking the only differences between 300 and 300c is the VGA bios but apparently there are more. BTW, do not try to connect 325lc/300c LCD to a 325l/300 mobo, it won't work.

The 325lc came with a modem board, it should be compatible with Macintosh mini DIN 8 pin modem cable (Mini-DIN 8 to DB25). But I don't have the environment to test it.




Mini-DIN8


Zenith 325x and ThinkPad 300x both support 10M ethernet. The connector looks like an external floppy port but it's in fact an Apple AAUI supporting 10Base-T and 10Base-2. It's still easy to find a dongle from eBay and it works well with modern ethernet cable.






300c/325lc has a 8.4" tft LCD with a max resolution of 640x480 16 colors.


Sharp LQ9D011 with 2 ccfl


The same LCD panel can be found on (at least) Compaq LTE 25C, 4/25C, 4/33C or Compaq Contura 4/25CX. ThinkPad 360c has the same 8.4" TFT but I cannot find my record...will check if they are the same later.

[tips]
1) The contrast key fn+f8 and fn+f9 still work on a TFT LCD 325lc. I tested it, and later on I damaged my LCD (by pressing fn+f8 for fun). Now I have a TFT Zenith with white screen and I'm still looking for the fried components...
2) after recap your boards, test it for 2+ hours to see if all other components work well. You may need to replace (a lot of other) diodes or triodes.

[ThinkDan]

Great post, thanks for sharing

[astral]

That LQ9D01 series panel will be found in any laptop released in 1992 or 93 that has an 8.4" TFT Color panel. I believe by 1994 Sharp had a newer model 8.4" panel out (was used in the LTE Elite 4/40CX, probably also the TP360C since it was released in '94). Other laptops that used the LQ9D01 include the LTE Lites as you mentioned, the Z-Note 425Lnc, the Apple PowerBook 180c, and also I think the Toshiba T4500C (not positive on that). They must all be recapped or they won't function properly. 100% of them have leaky caps at this point. Damage can get bad enough to ruin the panel (if you see one where a large horizontal block of pixels is dead, that's likely why).

[panips]

Yeah, it seems 8.4" TFT Sharp LQ9D01 units were pretty common then.
Just took a look at my 360c, and it used the new Sharp 8.4" TFT LQ9D03, and this might not be compatible with the ThinkPad 300c.

I have a table listing some of the LCDs here, for those which I can confirm on at least two of the same type of ThinkPads.