• Please review our updated Terms and Rules here

Toshiba Satellite Pro 430CDT laptop CMOS/RTC battery leaked

Wappynutter said:
Hey,@szelda . I can confirm this is correct as these images show here.
View attachment 1315933
View attachment 1315934
Pin 179 gets the signal through the via under the chip.
A view of the board with the clock generator ic removed.
View attachment 1315935
As far as the CLKB pin, I have probed it and identified it as the 8mhz clock signal but cannot find where it goes.

View attachment 1315936
View attachment 1315937
When I grab some free time I will do some more checks. im guessing we are both missing the 8mhz signal somewhere.
Hope this helps, good luck.
Click to expand...
Thank you so much! This is a huge help, and I really appreciate the thorough measurements.

Based on the information you provided, I’m going to bypass the original trace for the CPUCLK using a bodge wire. I’ll get back to you with the results as soon as I’m done. In the meantime, I’ll take a closer look at the CLKB point as well; if I manage to find where it leads, I’ll be sure to let you know.

Thanks again for your expert support!
 
I’m happy to report that the device is back to life! 🙂 @Wappynutter
After bypassing the CPUCLK, the Toshiba logo appeared on the very first boot. Although it initially hung at a blinking cursor and showed FF codes, the system stabilized after a few reboots. It now boots perfectly, passes memory tests, and remains stable even after being powered off for several hours.
I have one more observation regarding the CMOS: the machine still flags an error, even though the battery I installed has the correct voltage and significantly higher capacity than the original. What do you think could be the issue? It’s not a critical problem and I can live with it, but if there's a potential fix, I'd love to hear it.
I haven't located the CLKB point yet, but I'll try to trace it to see where it might connect.
My next step is a full recap using polymer capacitors, followed by final assembly. I’m also treating the bodge wires and damaged vias with Plastic 70 protective lacquer. If you need any specific measurements from this board for your own records, feel free to ask, I’d be happy to provide them!
Thank you again for your patience and expert guidance, I couldn't have revived this machine without your help!
 

Attachments

  • 1.jpeg
    1.jpeg
    197 KB · Views: 7
  • 2.jpg
    2.jpg
    2 MB · Views: 6
  • 3.jpg
    3.jpg
    1.9 MB · Views: 6
This is excellent news @szelda.
Alas mine still is not. I must have a problem not yet discovered as it seems my motherboard is doing all the right things as proven with resurrecting your battery damaged machine, but still not making a boot screen on mine.
I did find a problem on the cpu on mine.
A spot of blue corrosion on pin 285, a byte enable pin. I show this on page 3 of my post. Maybe I need to recheck this pin and consider delicately checking it is not broken and possibly try and add some solder to strengthen the pin. Also I still need to recheck my 110ct as it has also stopped working. These Toshiba laptops are a constant repair in progress.
Well done again, looking forward to seeing what you do with this now.
 
I'm sorry to hear that yours isn't up and running yet, but thank you for the kind words! @Wappynutter

Pin 285 definitely sounds critical; I hope you can save it with some delicate soldering. You are right, these vintage Toshibas feel like they are in a constant state of repair. I’m rooting for you with the 110CT, the 210CS, and that CPU pin! If you need any measurements or comparisons from this board to help with your troubleshooting, just let me know!

As for my next steps: I'm planning to use an IDE-to-CF adapter to replace the hard drive with a CompactFlash card and install Windows 95. I’m really looking forward to revisiting some of my favorite old games on it!
 
Hi everyone,

@Wappynutter, I would like to ask for your help again. I have replaced the electrolytic capacitors in the laptop and installed Windows 95, but I’m experiencing a strange issue.

The symptoms: At 800x600 resolution with 16 colors, it works flawlessly. However, if I switch to 256 colors, the screen becomes garbled with stripes during Windows boot, and the laptop freezes. Interestingly, if I let it sit in the BIOS for about 8 minutes before booting, the higher color depths work perfectly. It’s not a capacitor issue, as it behaved exactly the same way with the original ones.

I measured the voltage on the KM416C254 VRAM ICs (marked in blue), and I’m seeing a drop that I suspect is causing the instability. Meanwhile, the NDS9936 MOSFET shows a stable 4.95V.

My measurements on the VRAM VCC:

Power on: 4.88 V
BIOS / RAM test: 4.78 - 4.80 V
Windows boot (when it freezes): 4.73 - 4.76 V
Stable operation (after 8 mins wait): 4.76 V

My questions to you:

Could you possibly check the VRAM VCC voltage on your working unit to see if it’s also this low?

Where exactly do the VRAM VCC pins get their power from? It doesn't seem to have a direct connection to the NDS9936.

I know this is time-consuming, but if you have the time and opportunity, it would be a huge help for me to compare these values.

By the way, how is your laptop repair going? Hope you're making good progress with it! 🙂

Thank you, @Wappynutter, for your time and help! And thanks to everyone in advance for any suggestions!
 

Attachments

  • VGA card.jpg
    VGA card.jpg
    207.2 KB · Views: 3
Hey szelda, hope you are well. I'm having a break from my repair at the moment due to a lot of projects I'm working on including consoles, modern type AIO systems, older base units and even a commodore 64 and an old 300watt psu needing a recap.
Saying that, I took 20 minutes out of my hobby time to check on 2 of my 3 Toshiba systems for you.
Firstly I checked the 110ct and found this result.
20260429_104419.jpg20260429_104619.jpg
Not to dissimilar to your readings.
Then I checked the 210cs.
20260429_110156.jpg20260429_105959.jpg20260429_110009.jpg20260429_110017.jpg20260429_110028.jpg20260429_110035.jpg20260429_110049.jpg20260429_110100.jpg
So 4.8volts seems to be the norm.
You asked where this voltage gets generated from and testing in continuity mode vcc pins go here..
20260429_110949.jpg
Pin 3 on the connector on the bottom of the card. This connects on the motherboard here..
20260429_110958.jpg
Pin 3 on the motherboard. I traced this pin to here..
20260429_111018.jpg
A 5volt electrolytic cap next to the power button near the regulators etc..
Hope this helps. Maybe swap out the cap incase it's leaking or failing as it warms up.
Good luck, continued success with your aging Toshiba.
 
@Wappynutter Thank you very much for the help and the measurements. I’m doing well, and I hope everything is fine with you too! Good luck with all those projects! That’s a serious lineup!
Regarding the laptop: I have already replaced all the electrolytic capacitors with polymer types, but I don't think the fault lies there. I also experimented with a custom RC filter and extra buffering on the main input, but the voltage drop on the VRAM VCC rail persists regardless, so input noise is likely not the bottleneck.
My next plan is to trace the power rail back from the 100 µF buffer capacitor located next to the power button. I want to map out exactly where the 5V originates and which active components (PWM controller, MOSFET, inductor) the signal passes through.
I suspect the fault is within this section, as the continuity between the buffer and the VRAM pins is solid and the resistance is negligible, so the PCB trace itself is not broken.
I will get back to you with the results as soon as I make progress with the new measurements!
 
Good luck with your investigating. My first thought would be to check voltage at the connector pin.3 on the motherboard to rule out voltage loss or noise across the motherboard. I will grab another look if I get a chance later and check the power chips on the underside of the displayboard.
From Friday I will be on a cruise ship floating down the Nordic fjords for 7 days.
Keep sharing your findings.
 
So I have been unable to find anything on the main motherboard so far but have amended my displayboard pictures to take into account all the small smd capacitors that have continuity with the vcc pins on both sides of the displayboard. I found no direct connection to any of the ic's while probing.
All red marks show points of continuity on my 210cs.
20260429_171117.jpg20260429_172154.jpg
Hope this helps further. Maybe one of these caps is causing the power discrepancy.
 
Thank you so much for the very precise and detailed measurement, this helps a lot!
Have a lovely boat trip and enjoy the rest, it sounds wonderful! 🙂
I will definitely share my findings!
 
Hi everyone,

@Wappynutter I’d like to share my latest findings regarding the VRAM VCC rail, as I believe I’ve successfully localized the cause of the system freezes.

Testing Environment:

The VRAM VCC rail is supplied with 5.08V, which passes through a 20 mΩ shunt resistor and a 1BL3 (Schottky) diode before reaching the bulk filter capacitors. Measurements were taken with a multimeter (I am aware that high-speed dynamic transients would require an oscilloscope for full accuracy, but the trend is clearly visible even here).

Measurement Data (Voltage Drop Across the Diode):
  • Cold start (after 8 mins of warmup): 0.250V – 0.252V drop.
  • At operating temperature (after 20 mins): The drop decreases to 0.240V (consistent with the negative temperature coefficient of Schottky diodes).
  • At the moment of freezing: The voltage drop spikes to 0.263V – 0.271V.
Based on my calculations, the voltage reaching the VRAM is exactly the source voltage minus the diode's forward voltage (V_f). The diode itself isn't "faulty" in the traditional sense, but its characteristic curve cannot handle the dynamic load. There are no other significant voltage losses on the rail.

Conclusion:

In my opinion, the issue is caused by the transition to polymer capacitors. Although I have already reverted most capacitors on the 5V, 12V, and 15V rails back to standard electrolytic types, the system remains unstable. It is highly likely that the remaining polymers' ultra-low ESR causes sharp current transients that pull down the voltage across the diode whenever the VRAM demands a sudden burst of current. This momentary dip is enough to exceed the VRAM logic's tolerance, leading to a crash.

Next Steps:

I am looking for an Ultra-Low V_f diode, preferably a Trench Schottky (e.g., PMEG or V10P45 series), which can maintain a more stable output voltage under load and during transients.

Has anyone else encountered a similar "diode bottleneck" when using polymer capacitors in a legacy circuit?
 
Good luck with the diode and capacitor swaps. Hopefully this will cure your slight voltage drop underload. I am surprised that such a small amount triggers freezing and graphical errors. Share if you have any pictures so I can compare voltages if required. Keep us informed of your findings and repair log. Continued success repairing the Toshiba.
 
I really hope this is the root cause of the issue. For testing purposes, I'm going to try both a 30SQ045 Schottky diode and an LM74610-based ideal diode module. I will definitely share my findings once the parts arrive in a few weeks. Thanks! 🙂
 
You must log in or register to reply here.
Back
Top