Thinkpads Forum

Hello all,

My thinkpad 600E stopped working when restarting from BIOS after doing a system self test.
Was running a system self test after getting the 08611 track point error on startup, the errors came up when the motherboard test was in progress, then once that was finished, I pressed restart in the setup and just as the machine went to restart, it shut off and won't turn back on again, seem to make the AC adapter cut out too as the low battery light stops blinking too and i can hear a faint squealing from near the PSU input jack.

Power sequencing thing from powering the laptop with the battery instead of the AC charger when being powered on? (dont know how to explain my mental picture of the probable power up sequence when the laptop is powered up on the AC adapter)

It does stay powered when the battery is plugged in, but it cant start cause its bad. when the battery is removed from the machine it just cuts out and doesnt do anything (battery status LED doesnt blink anymore until AC adapter is unplugged and plugged back in.

Was also running for a hour or two prior.

The PSU used was a Genuine IBM power supply IBM FRU 02K6555

thanks

You'll probably need high-level electronics and troubleshooting skills to fix this one. It's similar to the restoration work fellow forum members panips and solidpro perform on ancient Thinkpads.

I'm afraid your 600E has a dead short on the main power rail per the squealing and PSU cutout...

I had a similar syndrome with a 600X I picked up from eBay. The repair process involved voltage injection and a thermal camera. If you're up for the challenge, here is the workflow I'd recommend:

1) Strip it down: Remove everything, CPU, RAM, CMOS battery, etc., until you have just the bare motherboard.

2) Visual Inspection: Check for any obviously charred or cracked tantalum capacitors or MOSFETs. Desolder any suspicious components and check the rail's resistance again.

3) Voltage Injection: Use a bench power supply to inject 1V to 2V (with a 1A current limit) through the DC jack. Use a thermal camera (or the rosin flux method) to locate any hot spots. In my case, the P-channel MOSFET Q56 heated up almost instantly. I then measured its resistance to ground on both the input and output pins.


4) Isolate the Short:
If the input pin shows near 0 ohms to ground: Desolder and replace the MOSFET, then retest.
If the output pin is shorted: Inject voltage directly into the output pad to find the next "downstream" component that's heating up.

For my board, the culprit was a purple 10uF conductive polymer aluminum solid capacitor. After removing it, the resistance returned to a healthy 60 ohms.


5) Rinse and Repeat: Continue this injection and testing cycle until the short is cleared.

My case was a bit unusual, I've rarely seen those polymer aluminum capacitors fail short; it’s almost always the tantalum caps that blow and cause a dead short in these vintage ThinkPads.

Good luck with the rescue!