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What are typical issues for Toshiba T1000LE's?

Well, I'm about to see if somebody on the forums is willing to repair it for me, because I've pretty much done all I can. I think the motherboard is fried, because I looked under two of the transistor thingies...
I'm still disgusted, and I did this days ago...

I'm going to try one more thing, then either try to find somebody else to fix it for cheap, or trade it for a similar laptop.
 
Hi,

I am also trying to repair my Toshiba T1000LE which hasn't been powered on for at least 6 months. Ai first I encountered similar symptoms (power LEDs blinking when pressing POWER button). After disassembly and replacing 3 electrolytics capacitors which has gone bad and cleaning the board, things became better. The computer boots up immediately after pressing the POWER button but shows the following message:

***SYSTEM CONFIGURATION ERROR***
A checksum error occurred in the configuration RAM.
Press any key for default set ....

and powers off immediately.

I have tried to (1) remove the battery and run with AC adapter only (2) run with both AC adapter & battery (3) run with 7.2V supplied directly to battery input contacts. Same symptoms. I have also tried to press F1 and other key on the keyboard to no avail. The system powers off immediately after the error message.

Any advice? Many thanks in advance.
 
I wish there was some help for them, be sad for them to go to waste. Caps are the most common component to die, I have replaced a few but not very experienced with them. So you could try to pick mdanh's brain about what he did with his caps. I'd be willing to take a shot at it but I have a couple similar laptops to work on for now.
 
Capt. 2110 said:
http://www.minuszerodegrees.net/manuals/Toshiba/Other/Toshiba T1000LE - Maintenance Manual.pdf

Try this, starting from page 10. It doesn't have your exact issue, but it gives you things to check.
Click to expand...

Thanks.

I already downloaded the manual earlier and read it carefully but sadly it only has high-level troubleshooting instructions. No schematics or expected voltage at various test points, for example.

I used an ESR meter and measured the ESR of all through-hole electrolytics capacitors on the mainboard and the power supply board (near the LCD). 1 of them had obviously leaked (ESR reads at least 100 Ohm with signs on the board) while two others have not yet leaked but read high ESR (1-2 Ohm). I replaced them with new capacitors having the same specs. For the rest of the capacitors, no leaking signs are found and their ESR are well within specs (0.3 - 0.5 Ohm) so I will leave them as is first.

My thoughts as to why the computer turns itself off after showing the error message (the manual says I can press any key to reset the configuration or F1 to enter BIOS, but I can't because it turns off immediately):

1. A short somewhere on the mainboard making the power supply shut down due to a short circuit. When manually supplying 7.2V through the battery contacts, my bench power supply registers as high as 1.89A when the computer is powered on before it is automatically shutdown, but this does not seem to be too large a current.

2. Something (e.g. faulty components) causes the power supply to think that the battery is dead (low voltage) and shutdown to prevent damage. After replacing the capacitors, I also tested the diodes but they seemed to be fine though. Other SMD components and several ICs are too difficult to test without a schematics.

3. It may be a software issue - the motherboard powers off since it can't read the configuration. For this I made a mistake of removing the rechargeable RTC battery to make it easier for disassembling, which was not necessary and might have caused the configuration to be lost. However, this seems unlikely to be an issue as the manual says the configuration can easily be reset.

My prognosis is that since the error message showed up upon booting on the screen with a beep in the PC speaker and the floppy drive seek sound, most of the board components are more than likely to be fine.

Any further thoughts? I will try to take some photos tonight.
 
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In response to your ideas:
1. A short is quite possible, since the laptops original PSU could only supply 1.7A. Check for shorts near the leaked capacitors, because the electrolyte likes making shorts. Also check your soldering, just in case.
2. Do you have a good battery, and if so, does it have a little thumbnail size piece of plastic by the contacts? I believe there might be a switch on the power board or LED board, and it could be the reason it won't boot. Just a theory, though.
3. I too doubt it's the software, although, the RTC battery is Ni-CD, so it could be dead, and it might cause an issue by being dead. Not sure on this one.
 
Capt. 2110 said:
In response to your ideas:
1. A short is quite possible, since the laptops original PSU could only supply 1.7A. Check for shorts near the leaked capacitors, because the electrolyte likes making shorts. Also check your soldering, just in case.
2. Do you have a good battery, and if so, does it have a little thumbnail size piece of plastic by the contacts? I believe there might be a switch on the power board or LED board, and it could be the reason it won't boot. Just a theory, though.
3. I too doubt it's the software, although, the RTC battery is Ni-CD, so it could be dead, and it might cause an issue by being dead. Not sure on this one.
Click to expand...

I checked carefully again today and there are no obvious shorts as far as I can see. For (2) the notebook comes with a battery which is long dead (voltage does not seem to increase after I leave it to connected to the powered lapted overnight). There are no switches on the battery, just 2 contacts, clearly marked as - and +, for power. What is the purpose of such a switch?
 
I also tried supplying 7.2V directly to the battery contacts to simulate the battery. Still same issues. Maybe the monitoring circuit expects typical behaviour for a battery output voltage (e.g. slight drop of voltage upon power on), which cannot be simulated by the regulated power supply, and thinks that the battery has issues and auto powers off.
 
The switch isn't on the battery, it's on the power board. I believe the battery has a piece of plastic on it that, once in the laptop, presses the switch. I'm not sure what the switch is for, if anything, but it was something I noticed during my repair attempts.
 
Capt. 2110 said:
The switch isn't on the battery, it's on the power board. I believe the battery has a piece of plastic on it that, once in the laptop, presses the switch. I'm not sure what the switch is for, if anything, but it was something I noticed during my repair attempts.
Click to expand...

I checked carefully and there was no piece of plastic on my battery or switch on the power board that activates when the battery is inserted. The battery clearly only has 2 metal contacts that come in touch with those on the board upon being inserted. Maybe perhaps slightly different board revision. Anyway I have given up, not worth the time and efforts to investigate further. I am going to sell the machine for parts on eBay.

There are other vintage 'toys' in my collection to be played with, next one being a Powerbook 165 that powers on and boots to System 7.1.1, just that the SCSI hard drive is dying and needs to be replaced. Sadly it's almost impossible to find 2.5" SCSI drive that is compatible with the Powerbook nowadays.
 
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Has anyone ever figured out what’s up with these? I just got one of these, recapped it, and it’s still just giving me the blinking “DC-in” light. This is the THIRD vintage Toshiba laptop I have bought that hasn’t worked. Why is the power supply circuitry in these so bad? Does anyone know of a fix? I’m really beginning to loathe the Toshibas.

Their gas plasma portables (like the T3100e) are much better than their battery-powered laptops, it seems.

It’s really sad, because this is one of the coolest XT-class laptops I have seen. Has a removable hard drive, high-res CGA display, a great keyboard, really everything you could ask for.
 
Well, I found where someone fixed theirs with similar symptoms to mine by replacing a particular mosfet, so I have ordered a replacement and we’ll see what happens...
 
Well, that didn’t fix it, and I tried some other things that didn’t help either. No more early Toshiba Laptops for me until someone figures out what’s up with them. I’ll stick with the gas plasma portables for Toshibas, which are much more reliable.
 
I have 2 T1000LE's and a T1200XE that all had these symptoms.
The T1200XE was fixed relatively simply by replacing all electrolytics and works perfectly fine to this day. The T1000LE's are a bit of a headscratcher.

I replaced all capacitors in the first one I got but it still didn't work. After replacing the Q502 MOSFET, which was clearly gone, the machine worked fine for a while.
After some time it stopped working in fast mode (9.54MHz), crashing as soon as it got through the BIOS POST, but worked fine in slow mode (4.77MHz).
After again some time it stopped working all together with the same "blinking DC IN LED" problem, I have not gotten back to this machine.

The second one worked like a charm after replacing all capacitors but soon after stopped working. Again, same symptoms.
I opened it up again yesterday to find Q502 burnt on this one too.

I think I have one of the required 2SJ182 MOSFETS in stock but I'll order a few of them so I can test.
At this time I have not found exactly what that MOSFET is for but it seems to be an inegral part of the power supply as the computer does not work without it.
It does some high-frequency switching of pretty high (for a 12V system) voltages, more on that in a later post.
It also seems that these MOSFETS tend to blow up when a capacitor is shorted or leaking. Though I replaced all of the through-hole ones the quality of some could be questionable.

I'm determined to find out what is up with these machines and their power supplies, I really like them.
I had one years back that had the exact same symptoms that I eventually threw out so it seems it is not uncommon for them to fail in this way.
 
If you find it out, please post here. I would love to fix one of these. Then I would actually have something good to say about them for a change.
 
I acquired a third machine last week and replaced all the electrolytics on it with high-end Panasonic and Würth capacitors. I also cleaned the board with soapy water and IPA and reflowed some components.
This machine now works flawlessly which allowed me to take some measurements, see attached images.
Could you try to see if your machine matches these?
I also started reverse-engineering the PCB as schematics are more descriptive but that will take time on this (at least) 4-layer PCB.

I also posted about this on my blog where you can see the high-res pictures and the oscilloscope traces (TP1-6): https://thomwijtenburg.nl/2020/05/27/debugging-the-t1000le-psu/

Caps-and-FETs-Annotated-768x1024.jpg
Jumpers-annotated-768x1024.jpg
 
I've managed to fix mine and I think it's permanent this time. It has been running fine for a couple of days now.

It turns out there were some traces running to and under IC501 that got severly damaged which prevented the PSU from stabilizing.
I also suspect that some of the caps I used in that machine were the root cause for it not running in fast mode and failing to boot altogether after a while.
Also I imaginge that this caused Q502 to blow as there was a lot of ripple and ringing on that transistor caused by out of spec caps.

On this particular machine (I call it machine #1) the voltages on the pins in my previous post were way below what they should be.
Around 4V on the 5V power rail and only 10V and -12V on the 12V and -22V lines respectively.

After replacing all the cheap Chinese caps with Würth and Panasonic-brand low-ESR ones and fixing the broken traces the machine runs perfectly fine, even in fast mode. No overheating components either.

My advice would be to check that your board has no damanged traces and replace the caps with quality brand (Panasonic, Würth, Nichicon and the likes) low-ESR 110°C ones.
Also check that no electrolyte has gotten underneath SMD components and has eaten away at traces of vias.

If you want to I can cross-check any voltages or signals on one of my machines but I think the root of the problem is cheap caps that can't handle the load of being in a switch-mode powersupply causing brownouts and noise in the PSU.

More detailed pictures can be found on my blog
 
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