An important note on the X20 PSU

[donluca]

Hi everyone,

just registered here because I managed to snag a Thinkpad X20 in good condition, albeit without a power supply.
When looking at the compatible IBM PSUs I saw that a 56W and a 72W PSU are available and wasn't sure which one to get.
Ideally I wanted the smaller and lighter 56W one.

So I looked at thinkwiki which is my reference and found out through
https://www.thinkwiki.org/wiki/Power_Co ... r_diameter
That all the X series used the 56W one so I went and bought one but then, while I was browsing a couple of IBM documents for information on the hardware of the X20, I discovered that the information on thinkwiki is wrong!

On
https://psref.lenovo.com/syspool/Sys/PD ... awbook.pdf
you can clearly see at pages 56 and 57 that both X20 and X21 need the 72W PSU!!

This is further confirmed here
https://m.mannil.ee/images/Lisad/IBM%20 ... ual%20.pdf
at page 48 it is stated that for the X20 and X21 you need the 72W PSU (while the X22, X23 and X24 use the 56W).

If someone has access to thinkwiki it would be great if this information could be updated ASAP to avoid making people waste money and potentially damaging the 56W PSU by using it with a X20 or X21.

Hope this helps!

[RealBlackStuff]

Corrected it on Thinkwiki.

[donluca]

Thanks!

Meanwhile I've managed to stop the seller in time and luckily he had the 72W PSU as well, so he sent the correct one.

When I have the X20 here I'll probably open a thread to narrate my adventures with the X20 which I picked up to use as a sort of Windows98 retrogaming machine for 1995-1999 era games that I played back in the day on my Pentium 166 MMX with a Matrox Millennium 3D GPU.

I know that there will be some hurdles but I've already done lots of research and hopefully I'll be able to push through and document all my findings.

I also want to see if the VRAM is upgradeable from 4MB to 8MB, hopefully it's on a separate chip and not integrated within the GPU, maybe I'll be able to desolder it and replace it with an 8MB chip.

[kfzhu1229]

There is also a similar problem with using the power supply of say a ThinkPad 770 or 600 on a power hungry beast like the A31p or T43p. All of these have the same connectors. And unlike newer Lenovo ones, or Dell chargers, there is no sense pin telling the computer what wattage is available for use. As a result, the computer will just draw whatever it needs.
More modern laptops with this kind of solution have protection on both the motherboard side - to power throttle your components if it feels that voltage drops too much (sign of reaching limits of the charger), and that the charger itself is rated to sustain under continuous full load for certain number of years. Either way it is still bad for the charger, the charger wire and body will both heat up more than it should, and the wire will start to age quicker, while the brick itself is more likely to fail.
Older chargers without this kind of behaviour however, could be damaging. like the case with the infamous ThinkPad 240 chargers.
So, before you plug the charger into your computer, inspect that the current rating on your charger is equal to or greater than the current rating written on your computer (say, 4.5A in the case of a T4x, 3.6A for an older ThinkPad). The voltage should exactly match too in most cases, but HP is infamous on indecisive on 18.5V or 19V or 19.1V on the charger voltage and always use them interchangeably.

[donluca]

Thanks for chiming in.

I don't know how well regulated those bricks are, but getting the voltage bang on is generally hard due to lots of variables in play (main AC voltage often fluctuates, temperature room, ventilation, components' age, etc.), so a 10% tolerance is often kept in mind when designing those circuits.

It is disturbing though that late 90s IBM machines (and power bricks) do not have any kind of protection

I'd expect it from older ones, but not for notebooks made further down the line.

Besides, today I should be getting my X20 and since my IBM PSU I've ordered won't be here before Monday, I'll probably hook up the X20 to my bench power supply, so I can also see, in the worst case scenario, how much the X20 truly draws: who knows, maybe the smaller 56W PSU could be fine as well!

[TPFanatic]

PC sales have generally risen over time


source: https://arstechnica.com/features/2005/12/total-share/

people also appear to be getting less intelligent over time

However, recent research in parts of Europe and the U.S. has started to see a plateau in intelligence scores, and even a reversal of the effect. For example, a recent study in the U.S. found lower vocabulary scores in newer cohorts. Shockingly, U.S. college graduates in the 2010s had lower vocabulary scores than their counterparts in the 1970s. Thus, to comprehensively test for the Flynn effect in recent years, Dworak et al. (2023) conducted a pre-registered study of almost 400,000 American adults between 2006-2018.

source: https://www.psychologytoday.com/us/blog ... ntelligent

the modern world of constant distractions not limited to PCs, whether or not affected by the computer industry's shift from exclusively B2B (big $$$) to including B2C (more $$, but more problems, also more jobs ), whether or not affected by people getting less intelligent, whether or not affected by anything else, all ties up why we need more safeguards to protect ourselves and our property, because fire is bad.

An ounce of prevention is worth a pound of cure.