I have 3 T4400 laptops with power supplies that I'm troubleshooting after replacing all the caps. I get enough life from the power boards to get blink codes (not post codes) via the battery light (hex 0d) . Laptop does not proceed to post, and I have determined that the blink codes originate from the PS itself.
No idea where to go from here. I did some basic continuity testing of the mosfets and transistors and they all seem ok. I've tested some of the voltage pins and get mixed results. I have a pinout via the service manual ( https://www.minuszerodegrees.net/manuals/Tosh … ce%20Manual.pdf )but it is not very descriptive. I also don't understand the blink code table.
Im hoping someone has dealt with these issues before.
bobconanwrote on 2024-03-04, 19:47:I have 3 T4400 laptops with power supplies that I'm troubleshooting after replacing all the caps. I get enough life from the pow […] Show full quote
I have 3 T4400 laptops with power supplies that I'm troubleshooting after replacing all the caps. I get enough life from the power boards to get blink codes (not post codes) via the battery light (hex 0d) . Laptop does not proceed to post, and I have determined that the blink codes originate from the PS itself.
No idea where to go from here. I did some basic continuity testing of the mosfets and transistors and they all seem ok. I've tested some of the voltage pins and get mixed results. I have a pinout via the service manual ( https://www.minuszerodegrees.net/manuals/Tosh … ce%20Manual.pdf )but it is not very descriptive. I also don't understand the blink code table.
Im hoping someone has dealt with these issues before.
Thanks
I've just found out that the graphical scanned version of the maintenance manual is missing information compared to the purely textual form. This is from the ATLAS 95 cd where the password to install is now known to be CHEESE 😁
To get to the text outside of a Windows 98 VM, I looked inside \DATA\TEXT\MMS.RAW with notepad++ at line 308055, there are complete power board diagnostic codes listed for the T4400!:
1<page:2-8> 2 3 <fig id=MMS\4400SXC\44SX2_9.tif>Page 2-9</fig> 4 5 6 The following timing chart shows the example, that 7 the status is 5h (0101). Read the timing chart from 8 right to left. 9 10 Bit O Bit 1 Bit 2 Bit 3 11 1 0 1 0 12 ON ---+ +------+ +---+ +------+ +---+ 13 | | | | | | | | | 14Battery | | | | | | | | | 15 | | | | | | | | | 16 +------------+ +---+ +----+ +---+ +---- 17 OFF 18 +------------+------+---+---+----+------+---+---´ 19 2s 1s 0.5s 0.5s 0.5s 1s 0.5s 0.5s 20 21 -------------------> Time 22<-------------------- Reading 23 24 25 The status and its meaning are described in the 26 following table. 27 28 Table 2-a Power supply error status 29 30 Status Meaning 31 1h Overvoltage of AC adapter output voltage (more than +18 V ñ5%) 32 Dh Battery terminal is shorted 33 4h Overcurrent of charging current 34 5h Abnormal charging voltage 35 6h Abnormal battery voltage 36 7h Abnormal VCC (+5 V) voltage 37 8h Abnormal RAMV (+5 V for DRAM) voltage 38 9h VEE (-9 V) is shorted. 39 Ah VDD (+12 V) is shorted. 40 Bh VDSP (+12 V to +18 V for EL) is shorted. 41 Ch Desk station IV was turned off before the computer was turned off. 42 2h Abnormal temperature in the system (less than - 20ø C or more than 70ø C) 43 3h Abnormal charging (The system cannot stop charging.) 44 Eh Undervoltage of AC adapter output (less than +18 V ñ5%) 45 Fh Undercurrent of charging current 46 47 48 NOTE: The test checks the statuses in the order of the 49 indicators in the above chart. If an error is found, 50 the program stops at the indicated status. For 51 example, if it stops at 8h, the RAMV voltage is 52 abnormal. Statuses proceeding an error are normal. 53 54 55 If the battery indicator blinks at random, the AC 56 adapter or charging circuit may be damaged.
It's possible that the blink code table you're seeing that doesn't correlate is the printer port one, but that's an 8-bit value rather than 4 bit and displays all at once with a parallel port POST code reader. The power board is it's own microcontroller so completely separate from the main system board.
Hopefully you have more luck that I did, I got careless and tried to run this fairly immaculate T4400C before recapping the power board, worked for a bit but then smoke came out. The HDD EEPROM got fried and now I've recapped & repaired the power board, it appears the mainboard is also toast, giving no output codes on the parallel port. My theory is that electrolyte under the 35v caps got into one of the traces under the cap and put some high voltage into some low voltage circuitry.
Have you tried without the battery fitted? If you have, well, did you check for any bad traces under those removed caps? I found one of my T4400 power boards had two traces broken where the capacitor electrolyte had damaged them.
I've just found out that the graphical scanned version of the maintenance manual is missing information compared to the purely textual form. This is from the ATLAS 95 cd where the password to install is now known to be CHEESE 😁
This is Excellent.
I have tried it without the battery as well as powering them directly from the battery terminals. The motherboard on one of them is definitely toast. What happened was the janky floppy power cable mod was reversed and cooked the PS. I have an actual ac adapter now. But, ATM I have 3 dead PS , one working , and one yet to be recapped. I have hopes that I might be able to get 1 of the 3 bads to work. I'm building a a new workbench room and will have a scope set up. Maybe then.
I just acquired a plasma screen model with a damaged screen. I'm hoping that was the only problem and Im going to swap it with the good plasma screen I have. Gonne try putting the good ps and screen in it next week.
I've just found out that the graphical scanned version of the maintenance manual is missing information compared to the purely textual form. This is from the ATLAS 95 cd where the password to install is now known to be CHEESE 😁
This is Excellent.
I have tried it without the battery as well as powering them directly from the battery terminals. The motherboard on one of them is definitely toast. What happened was the janky floppy power cable mod was reversed and cooked the PS. I have an actual ac adapter now. But, ATM I have 3 dead PS , one working , and one yet to be recapped. I have hopes that I might be able to get 1 of the 3 bads to work. I'm building a a new workbench room and will have a scope set up. Maybe then.
I just acquired a plasma screen model with a damaged screen. I'm hoping that was the only problem and Im going to swap it with the good plasma screen I have. Gonne try putting the good ps and screen in it next week.
Ah, my main power connector for all the T4400's I've got right now is one of the floppy power cable > dc barrel jack that I use with my bench power supply. So far it's been safe since I left the tabs on and it can't be plugged in upside-down but it could be better - might use some low-temperature-melting plastic to make it more secure. It's a real shame that yours died from a reversed connector, I wouldn't really know where to start with that.
Even with that, I think possibly one board either killed the CPU or has developed some other power fault where it'll give a 5v power issue when started with the CPU connected. If the T4400 power supply is killing CPUs even after recapping I'm not sure how to tackle that apart from improve capacitance on the mainboard. So far I've replaced the 16v 47uF electrolytic SMD caps because when testing them off board they have 0% capacitance left and were leaking, putting tantalums in their place seems to work well, actually there are already some tantalum caps on the back of the mainboard. But I figure adding tantalums closer to the CPU can't hurt... much?
I've since got a proper PA2408U PSU but haven't properly tested that yet and it'll probably need some caps replaced if it's had lots of hours use. That's how it's been for my T19xx laptops with the 18v 1.7a psu, where the capacitors had leaked and corroded nearby traces in the PSU itself.
Hope you get at least one good DC PSU board soon 😀 Might be worth giving them a bath in an ultrasonic cleaner if you have access to one, the two trust-worthy DC PSU boards that were recapped and had traces repaired also got cleaned in the ultrasonic before recapping and I think that's made a difference. The last two I recapped haven't gone in the ultrasonic yet and one of them developed this new fault with the 5v power issue.
Also, I've had another experience with ultrasonic cleaning making a difference with recapping - my Toshiba XM3301 caddy CD-ROM drive needed every capacitor replaced on its main PCB, I did that and it still didn't work. But then I put the board in the ultrasonic cleaner and it worked properly after that. I suspect leaked capacitor electrolyte is hard to clean up completely with just manual cleaning.
If you do get a working PSU, don't get too disheartened if it doesn't start working after that. The PSU faults can easily kill CPUs and I've found on *two* mainboards that were dead that the 25mhz clock generator was damaged by the dying and unstable power supply board: Re: Bought these (retro) hardware today
Have a parallel port POST code reader handy to read whether the mainboard is functional or not, my ones with no working clock were completely dead until the SPXO was replaced and now the mainboards are functional again.
