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Toshiba T1200 psu pinout

A

ale_perez

New Member
Joined
Jul 12, 2021
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8
Location
Argentina
Hi everyone, good morning!

I'm Alejandro from Argentina, nice to be here! I have read a lot of messages from here for different reasons and finally, I have decided to be a member of the forum.
I hope to be helpful, I'm an electronic hobbyist with a bit of experience in repairs but this post is to ask for help

I have received a Toshiba T1200 notebook as a gift, but sadly, it doesn't have the PSU inner board. I have tried to google the pinout of the power supply without any success, it seems that Toshiba notebooks from the same era always have PSU problems. I have found a picture of it online https://pbs.twimg.com/media/DMRvEJYWkAIIcU1?format=jpg&name=large

Does anyone know the T1200 PSU pinout? Any schematics or replacement or advice about how to replace it? Any help is really welcome.

Thanks in advance!
 
Hello Alejandro.

The T1200's maintenance manual is at [here].
A description of the power supply is on page 1-11.
The pinout of the power supply is on page 2-8.
 
modem7 said:
Hello Alejandro.

The T1200's maintenance manual is at [here].
A description of the power supply is on page 1-11.
The pinout of the power supply is on page 2-8.
Click to expand...

Thanks for the response! I have checked it, but something that I don't understand is how PJ 16 works. I have found it in the manual as a "Power supply (signal)" connector, but no information related to it. I read the post https://www.vcfed.org/forum/forum/genres/pcs-and-clones/70426-help-to-fix-a-toshiba-t1200 that seems to have a clue about which signals are working there.

I'm planning to replace the PSU board with a set of DC-DC converter modules, but I'm afraid that the right voltages could be not enough to turn on the machine
 
Hello everyone!!

I have started to test the mainboard with mixed results.

* The power led (green) turns on.
* The LCD display shows clear borders, like a character line at the top and the bottom, but completely dark in the middle.
* The button that checks if the display is closed triggers a "beep" when it is pressed.
* No signals in FDD or HDD

I have cleared the board and I have not found any problem. No chips overheating, no magic smoke but it doesn't work, It seems the board is waiting for another signal that I don't know.
 
Hi everyone, good Sunday!

modem7 yes, I have checked the reset signal is working fine. The CPU receives a high (and short) pulse, but nothing works. The clock signals are ok, I have checked the clock signals related to the CPU and EMC chip, I will continue my research around the pins related to the power supply signals.
The reset signal 'clears' the LCD display and it returns to its empty state, so I suppose that video circuit is receiving the reset signal too.
I have found an NMI pin related to the power supply that makes a relationship between the DMA and EMC chips, so I will try to decode their role in the boot process.
My major concern is related to the RPDAT1 pin (of EMC chip). It seems that the chip is waiting for a kind of signal that I couldn't figure out how works, if anyone has a working T1200 I will appreciate any information that could provide me from it.

My next steps will be...
* Check other power supply related pins
* Right now I can't see any signal from SPDAT0 pin, that should send data to the power supply. I will try to figure out why it isn't providing any signal.
* Could be the BIOS eprom wrong? I need to check that.
 
Hi, good night everyone!

I have worked a bit more on the board, and I have got some life signals from it.
  • Now, when the reset signal ends the speaker returns a beeeeep long followed by two shorter beeps. Something curious is the same sequence is repeated if I press Enter.
  • I have been able to repair the inverter for the backlight. The module waits for +5V in the connector that is close to the bigger connector with display signals.
This status was the result of the following repairs:
  1. I have replaced the BIOS with a new one. For some reason, the original BIOS was corrupted.
  2. I have needed to open the output pin 36 of EMC in order to isolate the NMI power supply signal. With this connection, the BIOS can't continue with the boot process.
I feel that I'm close to repair it, but right now I'm getting out of options. Again, any help or comment is very welcome!

​​​​​​​Thanks!
 
Hi everyone, good morning!

I have decided to stop this 'resurrection' attempt now. I'm stuck in the following situation
  • The processor receives the reset signal and takes data from BIOS eprom.
  • The ram memory signals look fine, after replacing a memory that was bad. After replacing the bad ram the beep error code has disappeared.
  • I have been able to repair the inverter circuit, so the display is ok now.
  • I have replaced vram and video chip without any change in the image. The video chip and vrams are the same used by T1000 model,
  • I have tested the printer port, and it shows 55H code, sadly this error code is not documented.
I will keep the computer until getting a new idea or inspiration. I have confirmed the following information after my repairs:

PJ16 connector.

1 - IC6 - EXP/MEM IC - Pin 56 - RPDAT1: Receive PS data. This one is connected directly to EXP/MEM IC, we need to pay attention!
2 - IC6 - EXP/MEM IC - Pin 59 - SPDAT0: Send PS data. This is connected to the chip via a transistor
3 - GND
4 - RESET BTN (???? maybe +5V. when button is pressed a capacitor is charged, making a reset pulse.). No +5V, this is connected with RESET button to GND.
5 - IC11 - bus controller - PIN 49 - PS RESET - IC 17 - PIN2 - (pulse to ground for CPU reset) With a small electrolytic capacitor we can simulate the reset. +V of capacitor to this pin and the negative one to GND.
6 - +5V - VRAM power
7 - GND
8 - +12V - RS232 positive power
9 - -12V - RS232 negative power. Both RS232 voltages are not required.
10 - GND
11 - IC6 - EXP/MEM IC - Pin 54 - LBATO: low battery signal. With this one to GND turns on the battery low led.
12 - -12v - LCD negative power. I don't know which voltage is the original one, with -12V the display works fine

I have needed to open the PSNMI pin connection from EXP/MEM IC in order to continue with the boot process.

I hope to be helpful for anyone that is working in this machine.

Thanks to everyone for the support
 
Are there any electrolytic caps? Might remove and check them for leakage or being bad with a capacitor tester.

Something else to check is the CMOS battery and/or the main system battery. Many laptops old and new act erratically or don't work at all if those are dead/low.
 
Hi,
This post, and another couple on this forum, helped me so much with my own T1200 power supply repair. I just wanted to thank you all for your hard work. I wasn't able to repair the PSU either, but I managed to make a replacement board to just provide the voltage rails and get it to boot, which is enough for me. One day I might try and put LiPo charging and HDD switch on there but we will see.
github.com

GitHub - BasicCode/Toshiba-T1200-PSU: Replacement power supply for the Toshiba T1200 laptop computer.

Replacement power supply for the Toshiba T1200 laptop computer. - BasicCode/Toshiba-T1200-PSU
github.com github.com
 
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