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Toshiba T1900C

Thought I would comment on this thread.
I too am fighting to revive a T1900C.

Issues that I have found so far:
1) several large electrolytics on the FATSL1 (PSU) board were really bad/ leaky. Replaced.
2) one trace was damaged from the leaked acid
3) several (most) of the small surface mount electrolytics were also bad/leaky. 10uF/6.3V and 33uF/6.3V. Replaced.

I now have a PUS board that puts out +5V, +3.3V on all the right places, and the system seems to try to start. The rails come up, the drive spins up, the CAPS and NUMLOCK LEDs flash, ... then nothing.
The LCD never comes on, and I think that the machine is not surviving POST. So, I never get anything on the screen, no beeps nothing.

I've been doing all sorts of little debugs here and there but without a schematic, it's hard. Also, I know nothing of the history of this computer... maybe it died for deeper reasons than the PSU.

It's always a challenge taking a machine that is known dead for unknown reasons.
I think I probably have a good drive out of it however.

If anyone has any comments on what to check if all the power rails are up, but the machine never "boots", please chime in! I know there could be a million reasons though.

to the OP - what happened with your boards?
 
Hi,

I see that I accidentally replied to the old forum. (It seems the old forum is not read only).
Copy-paste from my answer here:

>Hi there, and happy new year!
>
>I had to give this one up. I ended up buying an ESR meter, but could not find the culprit from the psu.
>I also found 19V power source, but it too failed to bring life to this unit. I still have the laptop - board and
>everything in pieces in a box. It's been almost a year since I fiddled with this, I probably could not remember
>how to put the puzzle back together.

Twospruces response went to the old forum as well:

>I might be interested in the parts; I got to a dead end and eventually damaged the board a bit. Set it aside. Without a schematic it is a real
>struggle to repair!

I could donate the parts for your cause. But there's a catch, a big one: the Finnish post office.
They are a dealbreaker in most cases. I checked S size packet, 11 x 36 x 60cm in size will cost 45,90 € to ship to Canada.
Assuming that is your location...

I'd need to try to assemble it to a decree for all to fit to 11cm height packet or just ship the most essential parts, like
the motherboard and psu. I am going to keep the hard drive as I believe I may have use for it. The rest can go.

PM me, if you're still interested in these. I must warn you that these parts are tampered with by me and may very
well prove useless. You might be better off waiting to find another unit, even defective, that has not been opened yet.
 

Inspired by the video above, I figured what if my toshiba has similar simple mosfet issue.
So I pulled it out of the closet and started measuring voltages.

Soon I realized that the + rail on electrolytic caps are showing less than 1 volt on the psu.
The unit was there on the table for say 10-15 minutes while I was measuring voltage on different
parts of the pcb.

Then, disaster. Not exactly sure where i touched with my multimeter but nightmare - a big spark hit
near the power on switch. Soon after that one tiny component in the psu and the big component
(Toshiba T9901C) gave the magic smoke out :/. T9901C even visibly bulged and audibly cracked.

Aaah. This is unfortunately really, really toast now.

I wonder could I still learn something from this. Perhaps I will try to remove that T9901C from the pcb
and see if +rail voltage gets any better after that. It's a long shot after the spark and smoke show, but
what if that chip was shorted in the beginning causing the + rail voltage to drop. . .
 
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