ThinkPad T40 Fan No Voltage (F4 chip works)

[luca9903]

Hi,

I recently bought a T40. The PC Power On but the Fan doesn't start. I read it could be the F4 chip but testing it with a tester gives me 5 volt. I tried to test the fan connector and it seems the problem, no voltage.

What can I do to fix it?

Thanks in advance, waiting your answers.

[RealBlackStuff]

The F4 fuse should not measure anything!
You probably left the charger and/or the battery in.
Set your multitester to Continuity, it should beep when you put the two probes together.
Without AC/battery connected, touch both sides of F4, it should beep if OK.

[luca9903]

The F4 fuse should not measure anything!
You probably left the charger and/or the battery in.
Set your multitester to Continuity, it should beep when you put the two probes together.
Without AC/battery connected, touch both sides of F4, it should beep if OK.

So I have to test it with no AC plugged in? I havent got the sound tester i have the one with LCD.

[RealBlackStuff]

Correct.
http://www.wikihow.com/Test-a-Fuse-With-a-Multimeter

[luca9903]

Correct.
http://www.wikihow.com/Test-a-Fuse-With-a-Multimeter

I tried as you told... No it doesn't seems to work. what can I Do?

[RealBlackStuff]

What doesn't work?

[luca9903]

What doesn't work?

It doesn't show nothing, I tried it on another t40 and it shows values about 1.4. It shows Nothing (0)

[RealBlackStuff]

I'd say you have a blown fuse.

Last try (without AC or battery):
one end of fuse --> wire --> ground from --> C/D/AA/AAA battery --> from plus --> wire --> lightbulb --> wire --> other end of fuse.
If the bulb burns, then the fuse is OK.

[luca9903]

I'd say you have a blown fuse.

Last try (without AC or battery):
one end of fuse --> wire --> ground from --> C/D/AA/AAA battery --> from plus --> wire --> lightbulb --> wire --> other end of fuse.
If the bulb burns, then the fuse is OK.

I'm not an expert, I didn't understand this procedure... I will try if someone at home will help me. However, If it wouldn't work, what can I do? And If it works?

Thanks in advance.

[RealBlackStuff]

Sorry, can't help you any further.

[luca9903]

Sorry, can't help you any further.

I understand. But can you tell me what to do if the fuse burns or not?

[RealBlackStuff]

If you don't even understand how to make a simple fuse-tester, I'm not going to tell you anything else.

Someone else please chime in, I'm done here.

[rkawakami]

@luca9903:

It's possible that there is a language barrier here so I will try to keep this as basic as possible. A fuse is tested with an instrument called an ohmmeter. A "multimeter" usually has a setting (switch position) for OHMS or marked with a Ω symbol, along with settings for VOLTS or AMPS. Generally the two wire leads for the meter are RED and BLACK. If the leads are removable, you should plug in the red lead into the jack marked with a V or Ω. The black wire goes to COM (common). Put the meter in the ohms or Ω position. The meter's display should show OL (overload) or INF (infinity). Touch the two leads of the meter together. You should see in the meter's display "0". This means that the resistance is 0. If this does not happen, then you have not set the meter up correctly and it will be useless to continue.

In order to properly test a fuse on the motherboard, you need to keep the power to the laptop off. Remove the main battery and the AC adapter. Then put the two leads of the meter on either end of the fuse. If the meter reads 0, the fuse is GOOD. If the meter displays anything GREATER in value than 0, or very, very close to 0 (example: 0.01), then the fuse is BAD. If the fuse is bad, then you have two options: A) remove the bad fuse and solder on a new one, or B) solder the new fuse directly on top of the bad one. If you do not have the ability or equipment to solder tiny parts such as the F4 fuse, then I would have somebody you trust to do it for you.

[luca9903]

@rkawakami:


Thanks for understanding, I'm not English. It is the better forum i Know. So I tried using the tester as RealBlack Stuff and You said, i check the red and black wire connection. I tried on a fan working T41 and the value is over 0 as you can see in photo and on non working t40 it shows nothing (i suppose 0).

https://drive.google.com/file/d/0B0aW-K ... sp=sharing (tester only)

https://drive.google.com/file/d/0B0aW-K ... sp=sharing (wotking t41 fan)

https://drive.google.com/file/d/0B0aW-K ... sp=sharing (non working t40 fan)

What could be the problem if u say that the value has to be 0?

Admin edit: Remove unnecessary quoting.

[rkawakami]

Please confirm:

1) I see in photo IMG_9354 that the meter in LOW OHMS (200Ω range) mode and I assume that the leads are not touching together OR to the fuse. If that is correct, the "1" in the meter means "infinity" which is to be expected.

2) Photo IMG_9355 shows meter reading 1.5Ω. IF the leads were connected to either end of the F4 fuse, then that means the fuse is probably good. For this to be confirmed, I would like to see the meter reading when the leads are touched together. In other words, NOT touching the fuse. If the meter reads the same 1.5Ω then that would confirm that the fuse is GOOD. It is possible that your meter is not exactly calibrated to display 0Ω when the meter leads are touching.

3) Photo IMG_9356 again shows the meter in the infinite ohms reading. If this photo was taken when the leads were across the F4 fuse, then the fuse is BAD.

I'm sorry that it was my mistake in assuming that the meter would display INF or OL when measuring infinity. Some meters actually will show "1" or "3" at the left end of the scale when presented with an "open" circuit. You should note the position of the decimal point in the display (to the right) as an indication of an improper reading (no digits directly before or after the decimal point).

[luca9903]

confirm 1

confirm 2

confirm 3

Thanks, I tried by touching the leads and shows 1 or bit more. I think know, after your explanation, that the fuse is blown. You said i can solder another fuse on it... what about taking the T41 one and put it on t40? which kind of solderer should I use?

Admin edit: Remove unnecessary quoting.

[rkawakami]

First a word of warning: If you are not exactly sure WHY the original fuse blew out, putting another fuse on the motherboard COULD result in another blown fuse. For example, if you were playing around with the fan power socket with the system powered up, then there was a good chance that something bad happened. Or, if you replaced the original fan and suddenly the replacement is not working too, then the replacement fan could have damaged the fuse. Putting another fuse on the board while keeping a "bad" fan installed, could cause the new fuse the blow as well.

With that out of the way, as long as you replace the F4 fuse with another 0.5A fuse, then it should work. I believe that the T41 F4 fuse is the same one. You will need a low-wattage (about 25W) soldering iron with as fine (small diameter) a tip as possible. Good eyes (or magnifying glass), steady hands, tweezers and very small diameter solder (0.5mm or 0.7mm) works well.

To remove the bad fuse could cause damage to the board, making it impossible to install a new fuse. What you are about to do is "piggyback" the new fuse on top of the bad one. I would first start by applying a very small amount of solder onto the replacement fuse BEFORE even trying to mount it on the "bad" fuse. Heat one end of the fuse with the tip of the iron and then feed a very small amount of solder onto it. It should melt and adhere to the end of the fuse. Let it cool and then do the same thing to the other end of the fuse. When both ends are done, test it with the multimeter to make sure it still reads 0 (or ~1.5, in your case) ohms. Place the new fuse on top of the old one. Holding the center of the fuse down with tweezers or small screwdriver, heat one end of the new fuse to melt the solder and bond it to the fuse already on the motherboard. Let it cool and push on the fuse to make sure it's firmly attached. Then, still holding down the fuse, heat the opposite end until it is also bonded to the old fuse. I would again use the multimeter and test to make sure that the fuse is still reading near 0 ohms.

That should complete the fuse operation. Re-assemble the system and test.

[luca9903]

Really Thanks for your Help, I decided to give up because I don't have the correct solderer. Hope the seller will accept my refund request... if not I'll try. Hoping for the first. Thank you so much.


Admin edit: Remove unnecessary quoting.