EEVblog 1527 - Toshiba T1000LE DOS Vintage Laptop Repair HELL - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: February 02, 2023, 11:22:31 pm
content: his Ebay Toshiba T1000LE vintage DOS In ROM laptop repair turned out looking promising until, well, it didn't...Service manual:https://www.minuszerodegrees.net/manuals/Toshiba/Other/Toshiba%20T1000LE%20-%20Maintenance%20Manual.pdf

author: .RC.
author_rank: Frequent Contributor
timestamp: February 03, 2023, 10:44:33 am
content: I take it is just a rebadged Cyberdyne product?

author: thm_w
author_rank: Super Contributor
timestamp: February 04, 2023, 07:31:23 am
content: As mentioned in the comments some parts are blown, C520, then another tantalum? cap under R513. If the rail was going overvoltage would make sense why they blew (the 7V you saw).Might be worth clean and replace those, but, if those logic ICs were damaged from the same overvoltage then may not be worth it.Soldering leaked electrolyte smells horrible, cat piss level of stench. Possible hot soapy water might be a better initial cleaner here:https://www.eevblog.com/forum/beginners/what-chemical-to-clean-the-pcb-after-leaking-capacitors/

author: EEVblog
author_rank: Unknown
timestamp: February 04, 2023, 08:54:15 am
content: Quote from: thm_w on February 04, 2023, 07:31:23 amYeah, there is a non-zero chance of going to all the effort of cleaning it, and repairing all the traces and failed components only to find that a bunch of chips are fried.Best bet would be the find a way to bypass on the PSU and feed in an external supply. Unfortunately no schematic is available, and I don't have a good unit to compare to.

author: c64
author_rank: Frequent Contributor
timestamp: February 04, 2023, 11:34:50 pm
content: I have the same model, also not working. Didn't see any broken traces though.Half of the paint from the lid was already missing, so I just peeled it all off. Now I have silver lid- but surface is not perfect.Why would you buy it from 'merica? They are not super rare here. For example this one sold for $125 just last monthhttps://www.ebay.com.au/itm/Toshiba-T1200-Laptop-Model-PA7048EA-Good-Condtion-Parts-or-Repair-/325476605763

author: EEVblog
author_rank: Unknown
timestamp: February 05, 2023, 09:53:42 am
content: Quote from: c64 on February 04, 2023, 11:34:50 pmThat's not the DOS in ROM version.

author: vasonline
author_rank: Contributor
timestamp: February 05, 2023, 10:46:31 am
content: Hi Dave,I have the same T1000LE repaired during the Covid time.At one point I had abandonned the project, but I went trough.Some things I learned from that experience:(you might already know some of them? - I saw some mis-information in one of the YT comments)- You do not need the battery installed to power the laptop.- You _do_ need the hard disk installed. There is a switch on the MB/HDD that will press in when installed. Laptop wil turn on and will shut off w/o HDD. Very confusing!- There is a small nicad for RTC. Behind the insulating tape, it was leaking - removed- The power brick is not a problem at all.- Screwing out and pressing in the last screw is easier for lifting the keyboard. (had trouble with that too)- The LED board with the charger/battery is not the problem (Caps were good there on mine too)- If Q504 blew, you will have trouble getting the DC IN light staying on. So that's good.- My laptop blew Q504 and C524: I believe this was caused by myself, by the initial powering on. (not knowing what had happend inside to the power supply capacitors.)- Between T9041 and C524 (that blew) I had a broken trace - repaired.- The logic chips were not damaged by the overvoltage that blew C524- Went over the whole thing with vinegar, toothbrush and IPA.Afterwards;- I haven't seen much of the DOS in rom, mine boots straight off the HDD. I'm not sure it has that feature. (fine for me).- I had to open the keyboard, because the corrosive atmosphere had corroded some traces (fix with conductive paint) or maybe someone spilled liquid in there?- You need the change the floppy belt.- Battery charger works, as an experiment, I charged up six NiMh cells with it, and it would run on that just fine.With new caps, broken trace repaired, new Q504 and C524 my T1000LE works.I attemped to draw a (sort of) schematic of the PSU (very incomplete)I'll post it here, maybe it is helpful?pic of floppy drivepic of how to open battery pack w/o destruction.pic of completed t1000lepic of schematicalso check out this site (not mine):https://thomwijtenburg.nl/2020/06/19/t1000le-psu-the-finale-hopefully/Greetings & good luck!

author: Ranayna
author_rank: Super Contributor
timestamp: February 05, 2023, 12:02:39 pm
content: Oh wow.From the outside, that notebook looked to be in an excellent condition. That must be really close to the original coloring.A shame that it is a mess on the inside.

author: psychoacoustic
author_rank: Newbie
timestamp: February 06, 2023, 06:53:38 pm
content: Watching this episode made me think I should examine the Epson PX-4 I have lying in the attic and recap it. Even though it still works fine (even the Cassette which acts like a floppy drive), I don't want those caps to spill their guts and corrode the board. I open it up and...They all look pristine. Nearly 40 years old (I saw datecodes of 1985 on the chips) but the board looks beautiful. I'd do more damage desoldering and removing the caps as long as I keep monitoring I figure.Now I don't have a LCR meter so I can't check if they are still reasonably close to their nominal values, but I think that'll be my next investment. Maybe I can catch degraded ones before they become an issue....now if only I could get a QWERTY keyboard for it (it's got a German QWERTZ)...

author: TimFox
author_rank: Super Contributor
timestamp: February 06, 2023, 07:09:16 pm
content: One detail I remember from that series of DOS laptops.The printer parallel port also served as a connector for an optional external disk drive.Therefore, the driver for that port had a faster rise time than normal "Centronix" ports.That caused me some difficulty using a commercial parallel port to general-purpose logic output box, due to crosstalk on the cable.(Also, the external box did not terminate the input properly.)

author: c64
author_rank: Frequent Contributor
timestamp: February 07, 2023, 10:38:18 pm
content: Quote from: vasonline on February 05, 2023, 10:46:31 amHow many NiCd cells were in the original battery pack? Internet says 4, but it wouldn't be 7.2V then

author: vasonline
author_rank: Contributor
timestamp: February 08, 2023, 01:41:56 pm
content: Quote from: c64 on February 07, 2023, 10:38:18 pmThere were 6 of them.With the DC IN led lit, but the rest of the laptop still powered off,you could see the charge pulses onto the battery pack terminals. (with scope).The TL1451A on the M/B has been an important chip for me, to check. together with the scope Shots from Thom.(a big thanks to him for putting that online- it was very helpfull at the time)

author: c64
author_rank: Frequent Contributor
timestamp: February 09, 2023, 08:09:05 pm
content: Quote from: vasonline on February 05, 2023, 10:46:31 amIs it enough to just press the switch?

author: vasonline
author_rank: Contributor
timestamp: February 11, 2023, 01:21:16 pm
content: Quote from: c64 on February 09, 2023, 08:09:05 pmYes.

author: GRADIENT
author_rank: Newbie
timestamp: March 16, 2023, 03:23:18 pm
content: I had pretty much all of the electrolytic capacitors leaking badly inside the laptop. Also all four of the 220uF 25V caps had leaked all over the place. I tried recapping and cleaning the board but still does not boot. Battery charging works fine and laptop even tries to start with the original battery without power supply.Some traces in between the IC505 and the C506 cap were corroded. I doubt, but I'm just wondering if anyone has removed IC505 and has a picture of the PCB below the IC. I Would like to check the continuity of the traces under the IC but would rather not remove the IC especially if it is not absolutely necessary. Also, still unsure whether I should go any further with the repair.Edit:By the way, if anyone needs a list of electrolytic capacitors for the laptop (I did not open LCD) then this is the list that I measured (no guarantees) when I recapped mine:1x 1000uF 6.3V 8x20mm2x 220uF 35V 8x20mm2x 120uF 25V 6.5x14mm2x 220uF 10V 6.5x12mm4x 220uF 25V 10x13mm

author: c64
author_rank: Frequent Contributor
timestamp: June 24, 2023, 11:12:33 pm
content: Dave if you feel lucky, there is one on eBay nowhttps://www.ebay.com.au/itm/304988392304

author: EEVblog
author_rank: Unknown
timestamp: June 27, 2023, 11:52:54 am
content: Quote from: c64 on June 24, 2023, 11:12:33 pmSadly not the same model. Could have done a screen swap if it was.

author: FuST
author_rank: Newbie
timestamp: September 12, 2023, 06:59:12 am
content: Just stumbled upon this thread, I might be able to help some people out here.I'm a bit swamped at the moment but I can provide measurements and/or 'scope shots from a couple of working T1000LE's to cross-check if someone wants to.Quote from: GRADIENT on March 16, 2023, 03:23:18 pmI can take some pictures if you're not comfortable removing it from your board.I'll have to dig up one of my machines and suck the IC out when I find the time so it'll take a while, trying to figure out which rail is failing is probably a bit quicker.My usual approach with the T-series PSU sections is something like this:- Remove all large capacitors used in the buck/boost converters (the ones hanging of the side of the board on the T1000LE.- Thoroughly clean the board with vinegar, water and IPA to remove all the gunk- Replace with new caps (I tend to use Panasonic FC series)- Hook up a 'scope to all the power rails (+5, +12, -12, -22, they're the jumperlinks near the center of the board)- Set to single-shot and power on the machine (a 4-channel 'scope is really handy for this), check for misbehaving rails.That way it's easier to narrow down the problem to one of the voltage rails instead of trying to look at the board as a whole.Quote from: vasonline on February 05, 2023, 10:46:31 amIf you could upload the files somewhere that'd be very helpful.I can see if I can combine it with the incomplete schematic I have for these and perhaps create a complete schematic for this machine.

author: rossoe
author_rank: Newbie
timestamp: February 24, 2025, 06:44:55 pm
content: Hello, I've just picked up aT1000LE, and trying to see if it can be repaired.Can someone tell me what value these tant caps are on the bottom of the main board:I think the larger one is a10 µF 16vbased on a similar sized cap lower down the board marked'106k 16x', it's hard to tell from the damage to the cap itself:For the smaller one I have no other reference to compare as they are both blown and blackened, from what little I can see it might have a value ending in35or85and voltage ending6U?

author: EEVblog
author_rank: Unknown
timestamp: February 25, 2025, 12:00:01 am
content: Quote from: rossoe on February 24, 2025, 06:44:55 pmI don't think it would be that critical, just try a 10uF or higher 16V or 25V and see. Plenty of pad room for a larger size if needed. Going larger value won't hurt.