T21 won't power on

[kishy]

Hey folks.
From Googling, and some previous knowledge of the T2x series, I understand that these machines seem to be prone to a sudden death condition where they either will not power on, or may suddenly die during use.

In my case, my T21 was previously working 100% fine and did not suffer any sudden death issues. It has a newer third-party replacement battery (purchased 2017 and used for many charge cycles successfully).

Yesterday, after a few months of disuse, I tried to turn it on and found it would not turn on at all. No LEDs, no charging indicator, no noises (no whining, clicks, buzzing, beeps), nothing at all. There is a faint smell of "magic smoke" (e.g. burnt electronics) in the vicinity of the hard drive slot. I have tried two different AC adapters, verified the AC adapters are functioning with my 600, tried with battery inserted or removed, and tried with hard drive inserted or removed. There are no signs of life whatsoever.

Before I tear this apart to inspect the motherboard, has anyone dealt with this and identified exactly which component(s) fail? I have doubts that it's the same as the "blink of death" where the ADP3421 must be replaced, as my computer is not doing anything at all. Although it may be a ridiculous investment of effort into a Pentium III computer, I'm willing to repair it if it is just a simple component on the board which may need to be replaced.

Regards

[ajkula66]

What you're describing doesn't seem like a BOD to me, and I've seen my share of those.

Try re-seating the RAM to see whether that does anything. Once you tear the system down, try swapping the CPU as well if you have a spare one on hand.

That's all I've got.

Good luck.

[BillP]

I've read that the ADP3421 current sense circuitry drifts and ultimately prevents the computer from powering up. When you are at the end of the road and nothing has revived the computer, try shorting pin 27 to pin 28 of the ADP3421. That should disable the current sense circuitry in the chip.

The datasheet for the ADP3421 is here: https://media.digikey.com/pdf/Data%20Sh ... DP3421.pdf

[kishy]

Well, I can report (neither happily nor sadly, just "matter-of-factly") that the T21 is now doing more than it was.

After sitting on the shelf in a fairly cold room for a few days, I pulled it out again to just see if it would do anything. The charging LED lit up when I connected the charger, and began the blink pattern as if the battery was almost full but still charging.

I powered it on and it booted successfully into the WinXP setup that was halfway done last time I used it. Come to think of it, I do not know why I didn't finish the WinXP setup. Perhaps it did suddenly power off and I did not know why at the time.

Anyway, I went to do other things while WinXP setup was completing, and when I returned to the T21, it had powered off. When I tried to turn it on again, it was exhibiting the BOD (quick blink of the HDD LED). Approximately 1 in every 30 attempts to power it on now will successfully power on, POST, and then begin loading the OS, except it will lock up or BSOD during the process with a different error each time, and the HDD LED will get stuck blinking in a very specific pattern.

There is definitely a power issue making things act stupid. I'll put it back on the shelf and investigate the ADP3421 when I'm bored in the future. Coincidentally, these chips are listed on Yahoo Auctions Japan where I've been shopping for other computer models recently. However I suspect they can be had much cheaper elsewhere.

[kfzhu1229]

Approximately 1 in every 30 attempts to power it on now will successfully power on, POST, and then begin loading the OS, except it will lock up or BSOD during the process with a different error each time, and the HDD LED will get stuck blinking in a very specific pattern.

Does pressing power button as many times as possible in a span of one second help the chance of powering the motherboard on? I think this is a different issue but I have a lot of A31p motherboards that takes multiple clicks of power button to power on, and sometimes I need to replug the battery and power supply. Now I have this occasionally with A30p where it takes 2 power button presses to turn on (with a highly charged CMOS battery).

[kishy]

Approximately 1 in every 30 attempts to power it on now will successfully power on, POST, and then begin loading the OS, except it will lock up or BSOD during the process with a different error each time, and the HDD LED will get stuck blinking in a very specific pattern.

Does pressing power button as many times as possible in a span of one second help the chance of powering the motherboard on? I think this is a different issue but I have a lot of A31p motherboards that takes multiple clicks of power button to power on, and sometimes I need to replug the battery and power supply. Now I have this occasionally with A30p where it takes 2 power button presses to turn on (with a highly charged CMOS battery).

If anything it seems to be the opposite...the longer it sits in between attempts, the more likely it is to power on.

It would be nice if there was a "pinpoint test" documented for these, e.g. measure voltage at a handful of specified component legs and verify all are in-spec. But since that's way lower-level than the average IT gets into, IBM never would have published those specs outside of factory QA materials.

[kfzhu1229]

If anything it seems to be the opposite...the longer it sits in between attempts, the more likely it is to power on.

I meant pressing the power button like 5 times in 1 second works better here. Pressing the button once and the backlight immediately comes on (IPS stays black, TFT turns white), status LED's come on and off as if it's usual, and no motorised components powered on, and stays there like that.