T43 sizzling and whistling noises on left side

[lophiomys]

Hi,

I just bought three T43 15inch with SXGA+ IPS.
All of them emit sizzling or whisteling high piched noise on left side.
The noise appears intermittend and it its there on AC and on battery,
I dont think it is connected to the fan.
I guess it could have to do something with the USB system as it is especially audible,
when an an external USB HDD is connected, which has its own power connection, and
if the T43 is connected to the mains AC.

What could be the cause of this?
Can we fix it, or is it the indication of some persistent damage?


This puzzels me, because none my my T42p do emit this kind of noise. (Only one has a noisy inverter whit white screens)


1x T43 2668-F7G (heavily used)
2x T43 2669-CTO (next to new, grade A)

(Besides they all have the whining fan problem, but this I know how to solve)

[RealBlackStuff]

Try in one machine to reseat the CPU, with fresh AS5, and if you can, using the long fan from your T42p.
Still sounding like an egg in a frying pan?
Check the DC connector, might be loose.

[lophiomys]

Hi RBS,
Thanks for your prompt suggestions.
The DC Connector on all T43's sits tight.
Long Fan M10, yes I am about to order some of those anyway.

I have just noticed that FW v1.27 was installed, and I updated to most recent v1.29 (Embedded 1.06).
The RelNotes of v1.28 mentions that it fixes something with a high piched noise...

<1.28 (1YET64WW)>
- (Fix) A high pitch audio noise may be produced by the battery mode
power management while a USB 1.1 device is connected.(BIOS)

But in my case it was "sizzeling" the loudest when connected to AC, and the connected USB Device was 2.0.
Strange.

[poshgeordie]

I'm linking my reply with the other similar topic thinkpads.com/forum/=102022, Weird noise on T41 Screen.

I think these two topics have similar issues.

Two possible reasons for this:

1. Smoothing capacitor beginning to leak or not filtering a supply line properly.

2. "Singing" smoothing inductor. Inductors are those square black components and consist of a coil of wire around a carbon-like former, and works to reduce any supply line interference.

As the supply voltage currents change, if either of these components are tending towards working less than perfectly, then their "effectiveness" will change as the currents, and amount of interferrence on those lines, change (sorry terrible sentence but hope you get the idea).

In this case it's possible one of the inductors is at fault since the problem becomes worse as the supply current through it increases. You may be able to find it by very careful listening and seeing if you can identify the problem inductor.

[Orclas]

PoshG: Wouldn't those components "be quiet" under battery power, assuming that battery power is even and smooth?

[poshgeordie]

You do have a point - hadn't thought of that!

However there are a lot of oscillators / mini switch mode voltage converters internally which could cause interference on the supply lines.
Also I'm not sure how the various supply voltage conversions (to produce the different supply voltages) are carried out but might be mini switch mode chips, though I have to admit are more likely to be using transistor DC voltage stabalisers. If they are SM these produce horrendeous amounts of supply line interference.

[Orclas]

Well, based on very limited knowledge, I do think that capacitors are used for general motherboard powersupply, regardless of AC mode. I also know that the CPU has its own power supply circuits, since it's an important component to keep cool on modern motherboards and graphics cards (I believe they're called PWM circuits). As if a T4x has such, I am clueless...

[poshgeordie]

Just to confirm that a MAX1901 Switch Mode chip is used with provides 12V, 5.5V, 3V outputs around the Thinkpad, and could be the problem component (it's also likely to be something else).

One of our test bench supplies uses SM technology and whistles away to itself during use, depending on the voltage output and output load - not sure which component(s) are creating the noise though.