Thermalwrong wrote on 2025-01-18, 17:33:

That will blow the fuse and/or the laptop will not start. You need 18v at 1.7a.

19v is also fine but the power supply must be limited to less than 1.8 amps, going over that with the battery fitted risks blowing the fuse because of how charging works on Toshiba laptops through all of the 90s - they whack max current into the battery when you plug in the charger and it uses that to determine if there's a power fault. If the current is too high the laptop will either go into a power fault mode which is where the power microcontroller shuts off power to avoid damage. Or the fuse will blow and you'll have to replace it

Oh! That is very good to know. 18V, hmm, I'll have to see if I have any router bricks or something that fits that requirement.

I'm running into a problem in section 4.9,step 5 of the previously linked PDF.

This is the step where the upper system board is to be removed. I've disconnected the nouse/KB cable as well as the RTC battery cable, and I've gotten both screws listed in step 4 (left side of upper system board and on the upper of the optional memory card connector).

There is still what appears to be a nut and bolt on the lower part of the optional memory card connector, but the service manual doesn't specifically call this out to be removed, so I've left it as is.

However, I can't seem to dislodge the upper system board. I'm not sure if it's only the PCB that js supposed to come out, or if the entire metal tray it's resting on is to be removed as a unit.

I've included some pictures of the laptop in its current state along with some closeups of the left and right sides of the upper system PCB to indicate that the screws called out in the service manual have indeed been removed.

Overview

Left side of upper system board

Right side, showing memory card connector

Darkblade48 wrote on 2025-01-21, 17:24:

I'm running into a problem in section 4.9,step 5 of the previously linked PDF. […]
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I'm running into a problem in section 4.9,step 5 of the previously linked PDF.

This is the step where the upper system board is to be removed. I've disconnected the nouse/KB cable as well as the RTC battery cable, and I've gotten both screws listed in step 4 (left side of upper system board and on the upper of the optional memory card connector).

There is still what appears to be a nut and bolt on the lower part of the optional memory card connector, but the service manual doesn't specifically call this out to be removed, so I've left it as is.

However, I can't seem to dislodge the upper system board. I'm not sure if it's only the PCB that js supposed to come out, or if the entire metal tray it's resting on is to be removed as a unit.

I've included some pictures of the laptop in its current state along with some closeups of the left and right sides of the upper system PCB to indicate that the screws called out in the service manual have indeed been removed.

Overview

The attachment 20250121_003745.jpg is no longer available

Left side of upper system board

The attachment 20250121_003752.jpg is no longer available

Right side, showing memory card connector

The attachment 20250121_003800.jpg is no longer available

Looks like you've got all the screws removed that you're supposed to. Now there are two PCB connectors holding the top board in place, the ones with the grey plastic covers over them.

They require some force to remove so wedging in a plastic tool (or metal tool, rather carefully) at these two points should work for getting the upper board off.

I usually put a hook tool or a plastic spudger into those spots and either lift up or twist the spudger which should apply enough force for the larger board to board connector to start moving. Then you can lift up the area by the smaller connector on the left to get the top PCB off of there.

The screw on the bottom of the laptop holds in the lower PCB & shield and that comes off a couple of steps later.

Thermalwrong wrote on 2025-01-21, 19:51:

Looks like you've got all the screws removed that you're supposed to. Now there are two PCB connectors holding the top board in […]
Show full quote

Looks like you've got all the screws removed that you're supposed to. Now there are two PCB connectors holding the top board in place, the ones with the grey plastic covers over them.

They require some force to remove so wedging in a plastic tool (or metal tool, rather carefully) at these two points should work for getting the upper board off.

The attachment t1960-remove-top-pcb.jpg is no longer available

I usually put a hook tool or a plastic spudger into those spots and either lift up or twist the spudger which should apply enough force for the larger board to board connector to start moving. Then you can lift up the area by the smaller connector on the left to get the top PCB off of there.

The screw on the bottom of the laptop holds in the lower PCB & shield and that comes off a couple of steps later.

I've indicated the screw/bolt in question at the bottom of the memory card connector. I'm not sure if this is the same screw we're talking about (you indicated it will be removed a couple of steps later)?

I'll give the plastic spudger a try tonight. I'm assuming it's just the PCB that comes out, and not the metal tray that it seems to be resting on?

Darkblade48 wrote on 2025-01-21, 20:33:

Thermalwrong wrote on 2025-01-21, 19:51:

Looks like you've got all the screws removed that you're supposed to. Now there are two PCB connectors holding the top board in […]
Show full quote

Looks like you've got all the screws removed that you're supposed to. Now there are two PCB connectors holding the top board in place, the ones with the grey plastic covers over them.

They require some force to remove so wedging in a plastic tool (or metal tool, rather carefully) at these two points should work for getting the upper board off.

The attachment t1960-remove-top-pcb.jpg is no longer available

I usually put a hook tool or a plastic spudger into those spots and either lift up or twist the spudger which should apply enough force for the larger board to board connector to start moving. Then you can lift up the area by the smaller connector on the left to get the top PCB off of there.

The screw on the bottom of the laptop holds in the lower PCB & shield and that comes off a couple of steps later.

I've indicated the screw/bolt in question at the bottom of the memory card connector. I'm not sure if this is the same screw we're talking about (you indicated it will be removed a couple of steps later)?

I'll give the plastic spudger a try tonight. I'm assuming it's just the PCB that comes out, and not the metal tray that it seems to be resting on?

That nut in the memory card slot is screwed in from the other side, can't be removed yet. Also shouldn't be removed 😀

It's just the top PCB that comes out, that gives you access to some more screws so that you can then remove the lower PCB and metal cover from the laptop's lower plastic base.

Thermalwrong wrote on 2025-01-21, 19:51:

I usually put a hook tool or a plastic spudger into those spots and either lift up or twist the spudger which should apply enough force for the larger board to board connector to start moving. Then you can lift up the area by the smaller connector on the left to get the top PCB off of there.

Excellent. I managed to get the upper PCB free with the technique exactly as you described

From what I can gather, my upper board appears to be different from the one you documented (different layouts for T1900 vs T1960, perhaps?)

I can only find one of those potentially bad electrolytic caps (C49, 33 uF, 6.3V), on the bottom side of the PCB. Can't tell if it's indeed bad yet, but at least I can have the footprint now and can measure to get an accurate sizing for a replacement MLCC of the same value.

Upper PCB - topside

Upper PCB - bottom (connector) side

Close up of the connector side. Note C49, 33 uF, 6.3V

Darkblade48 wrote on 2025-01-22, 17:05:

Thermalwrong wrote on 2025-01-21, 19:51:

I usually put a hook tool or a plastic spudger into those spots and either lift up or twist the spudger which should apply enough force for the larger board to board connector to start moving. Then you can lift up the area by the smaller connector on the left to get the top PCB off of there.

Excellent. I managed to get the upper PCB free with the technique exactly as you described

From what I can gather, my upper board appears to be different from the one you documented (different layouts for T1900 vs T1960, perhaps?)

Yep, the T1900 system board is different from the T1960 - they made quite a few revisions not just to the PCBs but also to cables in the laptop. My T1900's floppy drive is not great at reading all disks because the flex cable design is bad with traces that are too thin for the 5v power. But the T1910 and later revised the flex cable.

I can only find one of those potentially bad electrolytic caps (C49, 33 uF, 6.3V), on the bottom side of the PCB. Can't tell if […]
Show full quote

I can only find one of those potentially bad electrolytic caps (C49, 33 uF, 6.3V), on the bottom side of the PCB. Can't tell if it's indeed bad yet, but at least I can have the footprint now and can measure to get an accurate sizing for a replacement MLCC of the same value.

Upper PCB - topside

20250121_231922.jpg

Upper PCB - bottom (connector) side

20250121_231939.jpg

Close up of the connector side. Note C49, 33 uF, 6.3V

20250121_232010.jpg

That looks good, the little SMD electrolytic cap on your upper board should be fine as-is for a while, the legs are still shiny on it.

Not all SMD electrolytic caps are bad in my view, it seems to be this type of capacitor in the first few years of use - 1990 up to 1994 ish they were particularly bad and leaked, but I haven't seen this type of capacitor go bad on later stuff from the 90s... yet. Perhaps they'll all go bad in time but I suspect that it's down to certain chemistry changes over the years, where SMD and smaller capacitors are particularly affected. This thread talks about quaternary ammonium salt capacitors and I've seen some japanese youtube videos mention it
That T1960 might be from mid 94 or maybe 95 so mainly it should be just C511 that needs replacing to make the laptop power on again, I've fixed several T1910s with just that one cap.
Toshiba used high quality capacitors so were less affected by the later capacitor plague, for instance later laptops like the Satellite Pro 400 series use purple polymer capacitors instead of electrolytics so they don't leak / wear out in the same way (I have seen one or two fail, but it's rare)

But, before they did start using polymer caps they made extensive use of Elna brand capacitors which are known to leak pretty often especially the ones from 1992-3 ish time. For instance my T4400C from 1992 is kinda dead now because the elna caps all leaked and messed up the PSU board.
If you see any Elna branded caps in the power area then be suspicious of them - I've mostly seen them leak in areas that get highly stressed from being part of a switching DC-DC power supply which is I think what the C511 cap is on the T19xx series.

I ran into a small issue removing the floppy drive FPC last night (before you remove the metal tray that holds the lower PCB) - one of the latches on the housing connector snapped (yikes). I guess that happens with older plastics. Not sure if the FPC will be able to be held in place with sufficient pressure with just one intact clip, but I guess we'll see. On top of that, I'm willing to bet that the belt driving the floppy drive is also toast (I'll get around to opening it up as well, probably this weekend).

I'll update again once I have the lower PCB out, but from an initial glance, I didn't see any telltale signs that C511 had leaked (at least the pressure release slits at the top don't look bulged out).

I just want to say thank you for all your help so far! Hopefully I can restore this oldie.

Darkblade48 wrote on 2025-01-23, 20:48:

I ran into a small issue removing the floppy drive FPC last night (before you remove the metal tray that holds the lower PCB) - one of the latches on the housing connector snapped (yikes). I guess that happens with older plastics. Not sure if the FPC will be able to be held in place with sufficient pressure with just one intact clip, but I guess we'll see. On top of that, I'm willing to bet that the belt driving the floppy drive is also toast (I'll get around to opening it up as well, probably this weekend).

I'll update again once I have the lower PCB out, but from an initial glance, I didn't see any telltale signs that C511 had leaked (at least the pressure release slits at the top don't look bulged out).

I just want to say thank you for all your help so far! Hopefully I can restore this oldie.

Yeah the liquid crystal plastic stuff they used on the clips for FPC cables is pretty fragile - not from age, it's just fairly delicate compared to regular plastics. Don't worry if you break one of the clips that holds the pressure bar in place, even if both of them broke you could still manually push the pressure bar into place against the FPC connector and it would do its job allowing the FPC to connect to the mainboard. I've broken clips of similar connectors before now and it just makes it a bit more difficult to reinstall the FPC cable but still works afterwards.
The thing you should worry about is breaking that FPC cable, getting it out to get the motherboard out requires some finesse to avoid breaking it. Not too difficult but something to be aware of, FPC cables with 90 degree turns are weak at the bend points.

The belts are all toast now, which drive do you have? Personally I 3d print TPU replacement belts, they're all working pretty well.

For the C511 cap, what do you have for testing caps? Anything to test ESR would be ideal. Once you remove the cap you can see if it's leaked, or any yellow / brown stains on the nearby soldermask would be a good indication of leakage.

Thermalwrong wrote on 2025-01-24, 04:35:

Yeah the liquid crystal plastic stuff they used on the clips for FPC cables is pretty fragile - not from age, it's just fairly delicate compared to regular plastics. Don't worry if you break one of the clips that holds the pressure bar in place, even if both of them broke you could still manually push the pressure bar into place against the FPC connector and it would do its job allowing the FPC to connect to the mainboard. I've broken clips of similar connectors before now and it just makes it a bit more difficult to reinstall the FPC cable but still works afterwards.
The thing you should worry about is breaking that FPC cable, getting it out to get the motherboard out requires some finesse to avoid breaking it. Not too difficult but something to be aware of, FPC cables with 90 degree turns are weak at the bend points.

Thanks for the reassurance. I was very careful while maneuvering the FPC through the hole. I've read horror stories of FPCs tearing and then trying to rework them is just a complete nightmare.

Thermalwrong wrote on 2025-01-24, 04:35:

The belts are all toast now, which drive do you have? Personally I 3d print TPU replacement belts, they're all working pretty well.

I'm not quite sure which drive it is. I'll have to take it out and take a look. I have a 3D printer as well, but have never tried TPU, might give that a try. I also have a grab bag of belts (mainly for dealing with cassette tape decks and Walkmans), so maybe one will fit. You don't happen to have the measurements, do you?

Thermalwrong wrote on 2025-01-24, 04:35:

For the C511 cap, what do you have for testing caps? Anything to test ESR would be ideal. Once you remove the cap you can see if it's leaked, or any yellow / brown stains on the nearby soldermask would be a good indication of leakage.

I have a basic ESR meter (BSide ESR02 Pro), but it seems questionable when testing caps in circuit. I also have a digital multimeter with the standard basic functionality. Unfortunately, no LCR.

C511 is giving me some strange readings with the ESR meter, so I tried to remove it, to no avail. I've tried adding fresh (leaded) solder, adding some flux, removing it with a pump, and also with wick. I've had the most luck with wick, but the last remaining bits of solder seem to be stuck between the lead and the (very small) hole.

I've tried heating up the lead and pushing with the chisel (D24 sized) tip of the iron, to no avail. I've also tried heating up the solder for about 5-10 seconds, and then trying to blow it out with some canned compressed air

Got any tips for removing it?

C526, C527 and C528 look OK on initial visual inspection, but I'll have to do some more probing to see.

Aha, I managed to get the capacitor loose with the age-old technique of "heat up a solder joint, wiggle that lead, and alternate until the capacitor comes out" 😀

Getting the holes clean was a nightmare in itself though, but at least that's all cleaned up now.

Ironically though, the 2200 uF cap is perfectly fine.

Guess I'll have to go capacitor hunting!

Well, that was a good wild goose chase. Just took another look at your schematic, and realized I pulled out C509 and not C511! D'oh!

Checked C511 (1000 uf, 6.3V) and it does indeed seem bad!

For the square electrolytics (C526, C527, C528), I kept on getting weird "open circuit" readings on my ESR meter. Might have to pull one off board to actually check....

Thermalwrong wrote on 2024-02-16, 21:05:

So I did indeed get the T1900C laptop and I'm happy to report it had the same fault you're seeing! It would give the DC fault where the DC light would extinguish and begin to flash as soon as the power button was pushed.
After initial capacitor replacement of the big electrolytics, the fault persisted and the laptop would only power after heating with a hair dryer for a few seconds.

Just wanted to post here to give an updated version of this component map. I've now included an some more measurements for caps that were initially missing their diameter/height measurements, and have also included lead spacing (either 2.5 or 5 mm) for ease of ordering from your favourite component store.

I'll be taking apart my floppy drive soon to replace the belt, but still have to look into finding what the original belt diameter/width are. I suspect mine will have turned to goo, which is all too common with rubber belts from the 90s.

Hi, maybe this topic could interest you : Old Toshiba T series PSU issue, PA2478U

vbug wrote on 2025-02-02, 08:22:

Hi, maybe this topic could interest you : Old Toshiba T series PSU issue, PA2478U

Sadly, I don't have the original PSU for my T1960CS. I've still got it in pieces, and trying to figure out how to get the floppy drive apart to expose the belt so that I can get some rough measurements.

I found a seller in Germany on eBay, but he hasn't responded to my messages, so that might be a dead end.

Darkblade48 wrote on 2025-02-03, 01:52:

vbug wrote on 2025-02-02, 08:22:

Hi, maybe this topic could interest you : Old Toshiba T series PSU issue, PA2478U

Sadly, I don't have the original PSU for my T1960CS. I've still got it in pieces, and trying to figure out how to get the floppy drive apart to expose the belt so that I can get some rough measurements.

I found a seller in Germany on eBay, but he hasn't responded to my messages, so that might be a dead end.

Which drive is it? Could be a Citizen V1DA, or is it a Matsushita drive?
If it's the matsushita drive see these instructions: Re: Panasonic CF-41 drivers needed (solved)
For both types I use 3d printed belts with a 204mm circumference/length and about 0.5mm thickness. For the Citizen drives I find that 1.75 mm height/width is best and for the Matsushita EME278 / EME279 it seems that 1.5mm is best

Thanks for updating the capacitor map, that should be helpful for others fixing the caps on these 😀

Thermalwrong wrote on 2025-02-03, 03:56:

Which drive is it? Could be a Citizen V1DA, or is it a Matsushita drive? If it's the matsushita drive see these instructions: Re […]
Show full quote

Which drive is it? Could be a Citizen V1DA, or is it a Matsushita drive?
If it's the matsushita drive see these instructions: Re: Panasonic CF-41 drivers needed (solved)
For both types I use 3d printed belts with a 204mm circumference/length and about 0.5mm thickness. For the Citizen drives I find that 1.75 mm height/width is best and for the Matsushita EME278 / EME279 it seems that 1.5mm is best

Thanks for updating the capacitor map, that should be helpful for others fixing the caps on these 😀

It's a Citizen ZA0968P05 / V9DA-71B; I found a belt from a German seller on eBay and messaged them to see if they could ship to Canada, but they haven't responded in over a week...

Might try the 3D printed solution, but I have no experience with TPU yet, so we'll have to see.

Am I understanding correctly that for the Citizen drives, it's a 1.75 mm wide, 0.5 mm thick, and about 204 mm circumference?

Darkblade48 wrote on 2025-02-03, 20:28:

It's a Citizen ZA0968P05 / V9DA-71B; I found a belt from a German seller on eBay and messaged them to see if they could ship to […]
Show full quote

Thermalwrong wrote on 2025-02-03, 03:56:

Which drive is it? Could be a Citizen V1DA, or is it a Matsushita drive? If it's the matsushita drive see these instructions: Re […]
Show full quote

Which drive is it? Could be a Citizen V1DA, or is it a Matsushita drive?
If it's the matsushita drive see these instructions: Re: Panasonic CF-41 drivers needed (solved)
For both types I use 3d printed belts with a 204mm circumference/length and about 0.5mm thickness. For the Citizen drives I find that 1.75 mm height/width is best and for the Matsushita EME278 / EME279 it seems that 1.5mm is best

Thanks for updating the capacitor map, that should be helpful for others fixing the caps on these 😀

It's a Citizen ZA0968P05 / V9DA-71B; I found a belt from a German seller on eBay and messaged them to see if they could ship to Canada, but they haven't responded in over a week...

Might try the 3D printed solution, but I have no experience with TPU yet, so we'll have to see.

Am I understanding correctly that for the Citizen drives, it's a 1.75 mm wide, 0.5 mm thick, and about 204 mm circumference?

Yeah, the 1.75mm wide belt is ideal for the Citizen drive. Haven't had the belt slip off at all. Mostly I print them using a .25mm nozzle to get it set up for fine enough detail to make good belts. Check the belt with calipers after printing because the Z-height you use for regular printing might be too low / high for an accurate belt.
204mm circumference I think was 65mm diameter.
I might make some belts available, I printed a load of them last time I made some.

Thanks to @Thermalwrong for all your help!

I'd like to update this thread and say that my T1960CS is alive!