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I just want to share what happened to me with you guys.

My main computer is a Lenovo brand laptop which is going to turn 4 years old in a few months. What happened to me is that the other day, the power supply suddenly stopped working, the computer still worked, but I only had one single battery charge left (which is about 1h-1h30).
I can't know how exactly it broke down, but some measurement made me see that it only provided 14V instead of 20V.

The power supply is a brick which is absolutely unoppenable (without using an axe, which in this case it would be only openable once), so I have no chance to ever open it and fix something that is wrong in it (despite being probably able to). Of course it was made in China, like all things that break down suddenly like this.

As if this was not enough this happened 1 day after my start on a new job (where I have to use my own PC for the job 'cause they don't have enough of them).

Thankfully some colleague at my new job had a similar power supply (but a less powerful one, for a smaller computer), and measurement on this supply confirmed that it was effectively supposed to give 20V, not 14 (this was expected, but a confirmation is nice).

Another colleague of my dad had a power supply of a Dell PC which he didn't need any longer (the PC was too old I belive) for free, and gave it to my dad, and I was able to cut the cords and connect them together to get it working with my PC just fine ! Not only that, but now I have a much longer cord on the power supply (since the length of both cords adds up ).

There is nothing much impressive in this story but I learned something very important :

1) Hardware can fail anytime even when not expected (especially if it was made in China)

2) It is amazing how much helpful it is to have a job related to electricity, can save you loads of bucks and trouble. Someone who knowns nothing about electricity would probably have to buy a new power supply, or maybe even a new PC if they don't make the same models of supplies anymore or if they are not skilled enough to tell that the problem is the supply.

3) The life time of some device which owns a rechargeable battery is limited to the life time of it's power supply !
If the power supply fails, one last battery charge and your device is bricked, even if it is electronically fully functional.

This applies to PC, but also GBA, DS, cellphones, tablets, electric vehicles, etc, etc.... With the ever increasing amount of electronic things which relies on batteries, this is going to be a real problem. I never realized it until now.

Well, thankfully the power supply problem is a fairly generic one, with very few variables to work out (i.e. voltage, polarity, current rating). Except for the actual plug that connects to the device, it takes only a little bit of skill/knowledge with electronics to find and adapt a different supply.

You might also use external chargers, if they are a battery that can do this.

GBA SP, DS, and DS Lite charge fine from a USB charger. I used to charge my DS Lite from my Wii's USB port. Chinese power supplies are easy to replace with another Chinese power supply anyway.

I have three older laptops that I don't have power cables for. I'd love to put one of them in my Mame setup, and have been toying with the idea of taking another charger I have with similar DC output and hard-wiring it in. How can I figure out the polarity of the laptop's port when I don't have the original cable?

qbradq wrote:How can I figure out the polarity of [a used] laptop's port when I don't have the original cable?

Post the make and model here and someone might be kind enough to look it up for you.

If you're lucky, there will be a label somewhere to indicate the polarity. This one means the tip is positive and the ring is negative.

I had a laptop that needed a funky-shaped three-pin plug, and I didn't have the charger. I guessed that the two largest holes must have been positive and negative, and used a multimeter to read back the small residual charge from the battery to see which was which. I then chopped the end off of another charger and stuffed the bare wires into the holes. It looked ugly but worked great.

qbradq wrote:I have three older laptops that I don't have power cables for. I'd love to put one of them in my Mame setup, and have been toying with the idea of taking another charger I have with similar DC output and hard-wiring it in. How can I figure out the polarity of the laptop's port when I don't have the original cable?

One trick would be to use a multimeter and check for continuity between each terminal and a 'known' ground. Something like a USB port outer socket or a video output connector outer shell. Those should be ground and if you find one of the terminals is ground as well, BINGO, you've got your negative terminal of the connector. You can fairly safely assume the other is positive. Of course if either one isn't grounded then I guess this trick might not work and you wouldn't find continuity on either. I'd be surprised though, but I've never tried anything like this.

I'm pretty sure most modern notebook computers have voltage regulators inside, which means any PSU around 20VDC should work fine.
I've tested this on my older Dell which needed 20VDC. I used 2 12V lead acid batteries in series and it worked fine.

drk421 wrote:I'm pretty sure most modern notebook computers have voltage regulators inside, which means any PSU around 20VDC should work fine.
I've tested this on my older Dell which needed 20VDC. I used 2 12V lead acid batteries in series and it worked fine.

I have found that laptops pretty much don't care a whole lot what you give them, so long as the polarity is correct.*

*some laptops have silly communications in the charger to be sure it is a genuine charger

I used to get a lot of older HP laptops with GPUs damaged from overvoltage. HP used to use exactly 18.5 volts and trying to run one from a 19 volt universal adapter would kill it after a while.

Great input! I'll not try that with the HP then

Grapeshot wrote:I used to get a lot of older HP laptops with GPUs damaged from overvoltage. HP used to use exactly 18.5 volts and trying to run one from a 19 volt universal adapter would kill it after a while.

How in the world did this happen? The GPUs don't run off the DC adapter directly, and given the sensitive nature of precision electronics like a GPU I can not imagine it is not running off of regulated power. Are you sure they did not die from the infamous RoHS-compliant solder BGA issues of the mid-2000s?

The laptops I had this happen with were HP Pavilion ZT3000 with Mobility Radeon 9200 graphics from about 2004 (before RoHS). They had a host of issues, including that the power regulation and cooling for the GPU was inadequate, but they started failing en masse after about two weeks after we issued universal car/air AC adapters for them. HP denied warranty claims, citing overvoltage as the issue.

Grapeshot wrote:The laptops I had this happen with were HP Pavilion ZT3000 with Mobility Radeon 9200 graphics from about 2004 (before RoHS). They had a host of issues, including that the power regulation and cooling for the GPU was inadequate, but they started failing en masse after about two weeks after we issued universal car/air AC adapters for them. HP denied warranty claims, citing overvoltage as the issue.

How bizarre. Leave it to HP to make mistakes like these!