Dirty Power

[ryan42]

I have a theory about the pulsing fan problem. The T43 has dirty power. If you listen to the audio line off battery there's a electrical humming/clicking/popping sound that's really annoying which I sometimes observe at the same time the fan jumps. Any comments/ideas?

[jdhurst]

I don't think that is likely as a general statement. It doesn't cost any more (in practical terms) to create properly regulated power than modestly improperly regulated power, so why would responsible engineers create bad power?

Just to get an idea, I hooked up an incandesant load to a 72 watt power supply and took a look. The power supply produces well regulated power with a small ripple of about 25 millivolts about 2 microseconds wide about every 10 microseconds. Not my idea of dirty power.

There will be feedback currents within the system board, and perhaps the design is different than earlier models, but my guess is that the basic designs (in terms of paths, noise suppression and so on) are probably similar and well-established. Outside of customer expectations, they have to meet FCC requirements.

... JD Hurst

[christopher_wolf]

I have a theory about the pulsing fan problem. The T43 has dirty power. If you listen to the audio line off battery there's a electrical humming/clicking/popping sound that's really annoying which I sometimes observe at the same time the fan jumps. Any comments/ideas?

This isn't the problem with the pulsating fan on the T43; many Thinkpads have, thus far, had various issues with the fan and the fan speed. More likely, it really seems to have to do with the EC and its control system for the fan.

Also, I don't hear any noise on the audio jack line either; I used to with a ze5170 HP laptop I had...but that was the least of that HPs worries.

[ryan42]

I should have been more clear. the audio problems only come from wihtin the thinkpad when it is running on battery. It acts fine for about 10 seconds then there's noise and clicks. If someone wants to hear it i'll make a high gain or volume recording of it with another PC.

[christopher_wolf]

This isn't the buzzing that is associated with certain power schemes, is it? "Buzzing," "Crackling," "Ants," etc.

[ryan42]

No, that's the sound that comes from the LCD Inverter (or that's my personal guess) but this sound comes form the Audio Out and speakers.