Fixing the Toshiba T4700CT P30 Error

As I mentioned in my previous post after finding my Toshiba T4700CT, when I plugged in the AC adaptor it would not turn on and I was seeing a P30 error on this display.

Fortunately, there are many results on Google when you search for “Toshiba  T4xxxCT/CS P30 error”a, its fairly common the this series of laptop.

Although my write up is for a T4700CT with a P30 error, this issue may also display as a P31 error and affects Toshiba laptops with the 486 CPU  from the T4xxx and T19xx models.

The capacitor causing the error is a 1000uF 6.3VDC. You need to be mindful of the height, many replacements are much taller which can cause the power board not to fit back in the laptops plastic casing.

T4700CT Tear-down:

To access the power board you will need to dissemble the laptop by removing:

1. Hard drive
2. Any PCMCIA/Memory Cards & Battery.
3. Upper plastic top cover.
4. keyboard.
5. Status Indicator Panel
6. Cmos Battery & Microphone.
7. Screen.
8. Upper System Board.

The complete tear down instructions and diagrams can be found in Toshiba’s Maintenance manual for the T4700Cs, T4700CT & T4800CT, PDF Download button below:

The tear down instructions begin at page 125.

Removing T4700CT Bottom Screws (You only need to remove the 4 middle screws, the two floppy drive ones can be left in.

Keyboard & Top Cover Removed – You really want to try use a plastic prying tool, the plastic is old and screwdrivers might damage it.

T4700CT Screen Removed Showing the upper system board.

Power Board & System Board Toshiba T4700CT

The power-board is mounted on the back of the system board.

Cleaning the board and ordering replacement capacitors.

Cleaning the T4700CT Power Board

I couldn’t see any leaked electrolytic fluid on the PCB and cleaning it was probably overkill, but it was a Sunday and my 3 year old loves to learn new things.

Usually if there is a lot of electrolytic fluid stains or gunk I mix up a thick paste of water and bicarb soda, however this was just a light clean followed by spraying the board with contact cleaner.

For the replacement capacitors I ordered:

• 1000uf 6.3v capacitor – Panasonic EEUFS1A102.
• 3300uf 6.3v capacitor – Rubycon 6.3YXG3300MEFC12.5X20 (Note these need to be installed on a bit of an angle in order to clear, the factory capacitors are 17-18mm tall, the replacement is 20mm. )
• 1000uf 25v capacitor (The shortest capacitor I could find was 22mm so I decided not to replace this one).

It’s only the 6.3v 1000uf capacitor that needs replacing. The other capacitors may vary depending on your model.

T4700CT Power board and replacement caps

I didn’t take a photo of the replacement capacitors installed, I will try to take more photos on my next posts.

Once I replaced all the capacitors the laptop turned on with no issues and I successfully booted into Windows 95.

Look at that cool side-mount trackball mouse!

Look out my next post on Converting the Hard Drive to a Compact Flash hard drive and upgrading the CPU