Dead Toshiba T4500C

[VintageVic]

So,
I picked up another dead Toshiba from local auction site (for eur 19,- shipping included).
It's a T4500C with a dead battery and it won't start with the power charger either with battery unplugged.
Instead, the display shows a P30 error. Quick googling reveals, it is a "overvoltage" error. But the charger
seems to be ok, giving 15,16V with on load on it.

Cause might be dead caps at the power supply board. I listed all electrolytic caps there is (I already took the unit apart):
6,5V/1500uF (x2 units)
6,3V/1000uF (x1)
25V/470uF (x2)
16V/56uF (x2)
25V/33uF (x1)

I'm hunting cheap caps from ebay, since it'll take most likely 6 weeks to get all,
in the mean time I'm thinking if I could try to get some life by giving power to the board
from battery leads.




The battery is 9,6V, but there are 4 leads ? Does someone know the pinout for these ?
I'm not sure I have 9,6V psu, but maybe 9V / 10V I could find.

I tried the motherboard leads with multimeter after plugging the power supply on.
Let's read the contacts as A, B, C and D on the motherboard (A being negative, D being + on the motherboard).

When the power connector is plugged in, I'm getting zero voltage between A and D.
Since the battery is 9,6V, shouldn't this be also be 9,6V or slightly higher as the battery should be charged
from these pins ?

I'm getting 1,26V between A and B. And 4,86V between A and C contacts on the motherboard.
But, since I have no pinout, I can't imagine, what voltage these pins, B and C should have.

 

[ziloo]

.....the display shows a P30 error. ....

I have a dead Toshiba too that probably has the same issue. Would you please
explain what the display is .....and how you notice a P30 error? My laptop is
dead as a door nail and I get nothing on the screen...


ziloo :mrgreen:

 

[VintageVic]

Sure thing, Ziloo. The picture above is self explanatory, I hope ?
Older Toshiba models, like the T1900C (that I also have in pieces...) do not have that
little display there. Instead, it only has LED indicators for battery and so on.

The T4500C has that little display. It has charging icon there, when the power supply is plugged in.
When start button is pushed, the P30 error appears and nothing else happens.

At least, this one is not dead as a nail, eh ? =).

 

[Svenska]

I have a T4600C which had the same problem. Replacing the single 6.3V/1000uF capacitor fixed the P30 problem, but it still had problems. Being stupid, I replaced most capacitors with ones which were as close as I could find in my box of caps, and I did not record the original values.

Now, the system spuriously turns on when connected to power (even if connected to the DeskStation). Very creepy when it starts booting in the middle of the night...

Anyway, I assume that the whole T4500/T4600 series share the power circuitry. Could you please take a picture of the power supply of your device and label the capacitors? It seems that I should replace all caps with new and correct ones now...

Regarding the battery, I just replaced the NiMH cells in the past. That made the system work, but the shown percentage was completely off and the device would simply turn off after a few hours with 80% on the display. At that point, I stopped using the battery and a year later, stashed the system away completely.

 

[VintageVic]

Thanks for your input, Svenska!

I will be changing the 6.3V/1000uF cap first. I have already ordered the caps (from China), but it will take weeks before
they arrive to me. On the positive side, they cost next to nothing.

I have already ordered ESR meter a month ago. I'm hoping for it to arrive as well soon, it would help me document
capacitor esr values after removing them.

Just to be exact, did you have exactly the P30 error - and not P31 or anything else ? If it was P30 and you got it fixed,
this gives me hope that this unit might be salvageable as well.

I believe, that the 1000uF cap was at the very corner of the pcb. I will take a picture of the layout and check the locations
of each cap and their values for you. Might help someone else too later. However, currently I'm not with the parts, since I'm still
between two jobs (and two locations) for another couple of weeks.

Did you notice, that there was a small block between the capacitor pins? I believe that they are surface mount resistors.
Just wondering, if you accidentally removed them at the same time you removed the old caps ? They are very small in
size and even difficult to see, at least for me. If some got missing, perhaps that might cause some of the symptoms you mention on your device.


Edit:
Oh, by the way, I found PSU, that gave 9,23V (at 1 amp). I tried to connect it to bettery connectors (+ and -) leaving the two center
connectors empty. I could see some symbols on the little display. Trying to power on the laptop however did not have any effect.
No P30 error, nothing. Absolutely no change. Either that little PSU is not sufficient for the task or, maybe something is required
to be connected to the two center contacts as well. I'm not going to risk attempting to try that any further, just waiting to get the spare caps.

 

[Svenska]

I will be changing the 6.3V/1000uF cap first. I have already ordered the caps (from China), but it will take weeks before
they arrive to me. On the positive side, they cost next to nothing.

Well, this is why I replaced them with "mostly-fitting" parts. I guess my current problem is caused by some voltage leaking across the power switch - when the system has been turned on spuriously, I cannot turn it off by using the power switch. Therefore I'd like to replace all caps with their correct ones.

But I have time. The original replacement was done before I converted my second desk into a home office... so a few months more or less don't hurt. It's just very exhausting taking the unit apart.

Just to be exact, did you have exactly the P30 error - and not P31 or anything else ? If it was P30 and you got it fixed,
this gives me hope that this unit might be salvageable as well.

Yes, it was the P30 error specifically.

Did you notice, that there was a small block between the capacitor pins?

No, I didn't notice anything special when I had the unit open. I'm reasonably sure I wouldn't have removed resistors... but one never knows about one's past stupidities...

Oh, by the way, I found PSU, that gave 9,23V (at 1 amp). I tried to connect it to bettery connectors (+ and -) leaving the two center connectors empty. I could see some symbols on the little display. Trying to power on the laptop however did not have any effect.

I never attempted this. My battery has seen far better days, partially due to me messing around it incompetently years ago, and I am contemplating just removing the insides completely to make the unit lighter.

Back in spring, I also learned that the sound card inside the docking station had died (although the Panasonic CR-562 CD-ROM drive connected to it still worked fine). I never succeeded installing an IDE drive inside this unit, which is why I chose this specific drive.

 

[VintageVic]

Alright, I'm back at the drawing board.



I took picture of the power supply and marked the capacitor values. I'm making some progress myself here as well!
I was able to remove the 1000 uF cap (relatively) nicely without dropping the surface mount resistor away.

I noticed while I was in city that there was electric component shop not too far away. I became impatient and didn't want to wait
for 6 weeks any longer, since a few caps does not cost many euros in any way. I got all the needed caps for 6 euros - the ones that
are coming from china I might use on other projects later. Hey - maybe I need to buy dozen of these Toshibas for repair, since there are bunch of caps coming =).

And so, did I get rid of the P30 error by just replacing that one cap? Hell yeah ! But. I soon found out, I'm not out of the woods just yet:





No longer P30 error, but the little display shows "ON" symbol. And some strange 'faucet' symbol, what ever that means ?
I think also, the floppy symbol comes on and goes away, probably it is trying to see if anything is at the floppy drive.

But the screen. There are definitely some gray pixels there. The back light comes on. I noticed that I had left a couple of
ground wires unattached. I closed the power, attached the ground wires and the hard drive and tried again. Now a big blog of gray
instead of horizontal gray lines. On a third attempt, again, horizontal gray lines.

The hard drive is starting to spin. But I do not hear it starting to move the heads, like what I should expect if the unit was booting
from there.

Now I have to think a bit, what to try next. I'm assuming that it is pointless to start changing the rest of the caps, since the computer
is clearly now getting power. This issue most likely is not the power supply any more, but something else.

In any case, I'm grateful that there is at least back light and that the hard drive is spinning. I made a step to the right direction here =).

Thanks Svenska for your insight!!

 

[VintageVic]

I figured out, I might put the keyboard in.

Tried to press enter, but nothing happened. By pressing F1, I seemed to got into bios:


I escaped without saving from there. Of course, the bios battery is dead and the unit has forgotten what hard drive it
is attached into. That is why it will not boot.

It is real pity, that the up part has that gray block in it. after escaping bios, it goes like this:


I see the cursor is there, but not what is above it. Most likely and error like 'non system disk or disk error, insert boot disk'.

I need to look into the manual, but I'm starting to suspect that the unit has got wet, because it shows faucet logo.
damn, so close and so far...

I checked already that the busted T1900C I have has different type of screen connectors so it is at least not directly able to be replaced
here.

 

[VintageVic]

I opened the cover from the screen. There is definitely something going on there in the upper corner:


Perhaps this screen has at some point of it's life been warranty repaired? Looks like it has been tampered with.

Problem area matches to screen issue:


And I got whole new (warning?) icon:


Book? Toaster ? Yeah, maybe it knows it is toast .

 

[T-Squared]

That's a bookmark in a book. If I had to guess, that's for when the computer puts your info on the hard disk, goes to sleep, and turns off. (i.e. marking your place in your work to come back to it.)

I don't think it's impossible to fix a display like that. It looks like some of the screen cable's pads were not attached properly. It just needs to be pressed down while melting the solder. I've practiced on a similar screen.

Also, I think the faucet is meant for power-saving indication. Laptop computers at this time would change how much power went into the computer, like a faucet, to save power in the battery.

 

[VintageVic]

Thanks for your input T-Squared!

The bookmark icon vanished. I noticed that ribbon cable for floppy drive was loose. some pins maybe contacted wrong places there. I corrected
it and no more bookmark icon. I have to find out a way to attach that ribbon cable well. Originally it is pressed down and hold in place by tiny
plastic clip. I knew when I tried to open it, that this will break very easily. tried very carefully pry it open knowing that and it broke anyway.
Perhaps, if the plastic was new it was possible to open without breaking, but the old plastic is extremely brittle and for me not possible to open without breaking it.

About the cable pads... in my previous post I attached 6.jpg. In that upper corner there is definitely some sort of corrosion going on.
It looks like maybe someone did try to fix that earlier. Is this part the 'pad' you are referring to ?

 

[VintageVic]

Yay !

This makes me happy


I did give some heat with my soldering iron to the upper left corner contacts. At first nothing, but then
I heated one pin more and then I seem to have result there!

I left the big battery charging over night and indicator shows 100% now.


who knows, maybe it hold the laptop on for 50 seconds or so? But no matter, I was curious if it has any change
by trying to charge it.

But the next issue to tackle, why it wont boot ? Not from a hard drive, nor from boot floppy. It does not seem
to make big effort, just gives error about missing basic.

 

[T-Squared]

Yes, the short brown cables with the multiple silver pads. That does not look like corrosion to me. I think it is flux. (Used to make solder clean and shiny.) Flux is ok, and helps with connections, but you have to clean it off after use. (The other person who used it did not.)

I can offer some advice to fix that cable. But DO THIS AT YOUR OWN RISK. (Don't get angry at me if it doesn't work.) If you can't do this, try to ask someone who does know how to do it.

It might be hard, but if you can, put your screen on a surface where it will not be scratched, heat up your soldering iron if you have one... (And make sure the tip is clean, no black burned stuff on it, and use more flux if you can!)

1. Take a small wooden stick (About 1.5 mm in thickness. Maybe a tongue depressor will work), and, with the edge of the stick, press down a bit on the cable close to the solder pads, between the rectangle in the cable and the solder pads on the green board. (NOT ON THE SIDE WITH THE SCREEN GLASS)
2. If you touch each of the solder pads on that cable with the iron for one second or two, just enough to melt and turn shiny, you might be able to solder those cable wires back into place, but don't move the soldering iron side-to-side! (You might misalign the wires if you do.) Just press down lightly with the iron. Also, don't be scared about the soldering iron touching the brown cable. That is very heat-resistant.



OH! YOU DID IT! :D

Yes, that was not corrosion. If the corrosion melted into a brown liquid, then that's flux. That's for making solder clean and shiny.

 

[VintageVic]

Ah, you had discussed this at another topic already =).

The bios of this laptop is very lacking. No boot order, nothing about the floppy.
Hard drive options are: 510Mb drive or no drive at all. I cannot even specify cylinders, heads or sectors. it's just hard drive of that
type or none at all.

It spins the hard drive and spins the floppy on the floppy drive. But I can't hear head seeking the floppy at any point. I might need
to try to open the floppy drive and see if the head is very stuck.

 

[VintageVic]

I opened the floppy drive and confirmed that floppy stepper motor is not moving.
I can freely spin the stepper axel so it is not stuck. Drive does spin the disc.

I think this unit only requires +5V (based on the manual). So again, I don't think it is another power supply ussue.
Hmm. I wonder what to try next.

Edit:

Well, I got the head moving during start up by pressing the cable firmly at its connector.
I cleaned the heads and gave a drop of oil to the stepper axel and the rail.

During boot, it will spin the disc and sometimes (not always) tries to move the head.
Sometimes head may go from one extreme end to the other.

And finally, we are always back to "please use toshiba basic".

I've got a bunch of floppy drives, but of course none of them fits to this laptop. Of course,
the issue might be elsewhere than the floppy drive itself.

 

[VintageVic]

I tried the floppy. tried and tried, but no luck with it even after cleaning. No difference
with using DD floppies either. just no luck with it.

Then it occured to me that what if I put the hard drive to a desktop computer and see if
it would work there. Since I can think of only two ways to get this thing booting (floppy or hard drive)
it's only fair to entertain both options. But is it even IDE drive ? Quick googling revealed to me that it is.

You'll need adapter to connect the drive to an IDE cable though. I thought I might just have one such thing
and how fortunate, I was able to find it! Then to test with the desktop PC.

First things first, the BIOS. It did recognize the drive automatically immediately. However, the PC would not boot from it.
So I booted the desktop from a floppy. Went to C: drive and checked what DIR says. Empty! formatted, but completely
empty. No wonder the Toshiba would not boot from it.

Just in case, I removed any partitions, made new one and formatted the C: drive with dos 6.21 boot disk. Then
I copied the autoexec.bat and config.sys there and the rest under c:\dos.

Desktop would boot from the hard drive now. Aaaand.... SO WOULD THE TOSHIBA =D.



Muy bueno, muy bueno indeed .

I tried to read floppy after that, but still no luck with it. Heh, maybe it is broken after all.
A bit harder to transfer media to the Toshiba, but now I'm confident that it will be a working laptop soon!

 

[VintageVic]

Okay, one last visit to this thread.

The floppy drive seems to be defective but other than that, Toshiba is fine now!
I have put some media to it's hard drive and assembled the laptop. Tried out that
external mouse and keyboard work too. Did not try the trackball mouse, but I will.

I'm very happy about bringing back the dead laptop, eventhough I'm missing floppy.
Made a 'how to fix P30 error' video to youtube, starting from the point when I got the Toshiba:

https://youtu.be/OlGaYucskGQ

Very first tutorial video of mine, I have lessons to learn from speaking english to how to hold
the camera and about lighting... but if it helps someone with similar problem, I'm glad.
If it gets views, maybe I will try to make similar (but improved) how to -videos about fixing
or building other vintage stuff as well, since I'm often tinkering with something.

 

[Svenska]

No longer P30 error, but the little display shows "ON" symbol. And some strange 'faucet' symbol, what ever that means ?
I think also, the floppy symbol comes on and goes away, probably it is trying to see if anything is at the floppy drive.

The faucet symbol is the power consumption level, as configured in the BIOS (full speed, balanced, low speed, user-defined). It can be changed by a keyboard combination at runtime.

Of course, the bios battery is dead and the unit has forgotten what hard drive it is attached into. That is why it will not boot.

If I remember correctly, these devices do not actually have a BIOS battery.

I see the cursor is there, but not what is above it. Most likely and error like 'non system disk or disk error, insert boot disk'.

More likely, the message is about a missing ROM BIOS. That message appears when booting fails (e.g. when the hard drive does not have a partition marked as bootable - very confusing).

The bookmark icon vanished.

The bookmark icon denotes that the system will actually not power off when the power button is pressed, but it will go into suspend mode instead. This can also be toggled using a keyboard combination.

The bios of this laptop is very lacking. No boot order, nothing about the floppy.

Unfortunately, the boot order is fixed at "floppy, then hard disk". The BIOS appears to auto-detect the hard disk to some extent, but definitely does not like anything above 500 MB.

Just in case, I removed any partitions, made new one and formatted the C: drive with dos 6.21 boot disk. Then
I copied the autoexec.bat and config.sys there and the rest under c:\dos.

For the future, you might want to track down Toshiba DOS for these machines. It is needed to use the HardRAM feature and provides support for the power management if I remember correctly.

Okay, one last visit to this thread.

Hopefully, you will still read this message. I haven't checked this thread in a while...

Also, *thank you very very much for the PSU photo!*

 

[DeltaDon]

If pressing on the ribbon cable causes the floppy to work then the broken connector is your problem. The latching bar is necessary to press the ribbon against the connector contacts. Either repair the broken bar or replace the connector completely. MEK, methyl ethyl ketone, will "weld" many plastics and also completely dissolve it if too much is used. Nasty chemical, but useful for repairing some types of plastics. Do not repair in place of you will dissolve the ribbon and the main part of the connector!!!!!