T20 - Board component burned - can it be replaced ?

[dinos_2006]

Hi all and many thanks for any help,

Following many topics on the forum I have identified the burned component on my Thinkpad T20 2647-92U .
I have two questions -problems though :
1. I dont know what electronic component this is (i have tried two hours with google by searching the letters - numbers on - but no lack).
2. I dont know if it can be replaced.

The burned component is the first of the series of five from right to left:
http://i111.photobucket.com/albums/n124 ... CN3574.jpg
and
the board photo for reference is
http://i111.photobucket.com/albums/n124 ... CN3575.jpg

Thanks

[rkawakami]

1. I dont know what electronic component this is (i have tried two hours with google by searching the letters - numbers on - but no lack).
2. I dont know if it can be replaced.

1) Component appears to be an electrolytic capacitor (i.e. polarized). This is noted by the painted stripe on one 'end' of the part and the associated '+' sign on the printed circuit board. The '220' code on the top is a reference to the value of the capacitor. I initially thought that it meant 22pF (picofarad) but this didn't make too much sense to me as I'm not aware of any polarized capacitor with this small of a capacitance value. After searching for surface mount polarized capacitor codes, I found that the numbers are in 'uF' (microfarad). The first two numbers are the value (in 'uF' in this case) and the third digit is a multipler (power of 10). So for '220' that means 22uF X 10^0 or 22uF x 1. The 'e' after the '220' should be a voltage code. That appears to mean '16V'. That makes much more sense for a polarized cap. So in short what you are looking for is a surface mounted, electrolytic capacitor with a value of 22uF and a voltage rating of 16V.

2) It can be replaced using a standard soldering iron but you have to be very careful not to overheat the board. A 25 watt (or temperature controlled) soldering iron should be enough. Removing the old part can be easier sometimes if it is simply cut away. Using a pair of diagonal cutters you can cut through the middle of the part and then use a fine-tipped soldering iron to heat either end and remove the remains. Use many small, nibbling cuts to divide the old part and not one complete cut. Since this appears to be a capacitor which is intended to filter out power supply noise, you may be able to safely remove it and not install a replacement. I base this upon the fact that there are four more capacitors nearby and that they are located next to the CPU. There may be enough filtering provided by the remaining capacitors. However, it is possible that during heavy CPU usage that an error could develop. That may led to a system hang.

All of the capacitor information was gathered from this site:

http://library.solarbotics.net/pieces/p ... p_code.htm

Near the bottom of that page is where they describe surface mount (SMD) electrolytic capacitors.

I do have some questions... Can you describe what the problem is with your laptop? Does it not power on? If so, are there any indications of it trying to turn on, like flashing LEDs or spinning fan? If it does seem to power up normally, but fails later on, can you describe what/when that happens?

Good luck!

[dinos_2006]

Hi ,

Many Many thanks to you RAY for such a detailed answer.
With respect to more details (i will take advantage of your knowledge)
the notebook while running normal office application was shut off.
No led after that time was working. I initially removed battery
and checked if I had power in the power cord - supply. The power arriving from the supply to the notebook was 17.00 V inline with the specifications.
Since no led was active I followed all the details in the IBM handbook
and removed memory and stuff. Then I meaured the voltage arriving at the motherboard in order to be sure (or so I think!) that I didnt had a broken I/O
port like that
link
but the voltage was good 17.00.
The manual suggested that only system board could be the case
of failure since I had good power but no led working. In my last effort to check for the problem I connected again the board with the power supply . Then the smoke came from the first of the five capacitors as I have now learned. By testing the board with the multimeter i identify the following situation. All of the capacitors seem to be in a short circuit state since by touching with one probe
the left side of the first one and the right side of the fourth one
there is a short circuit sound.
Is this normal?
If you have any idea if there may be more problems apart from that please let me know.

[rkawakami]

Most likely the cause of failure was an internal short inside the capacitor. There may also be a fuse that has blown. I had a newly-obtained T22 opened up a couple of days ago but don't remember if the fuses on that motherboard are the same ones as on a T23 that I recently replaced. From your second picture (DSCN3575.jpg), look at the Ultrabay battery connector near the bottom right corner (the black plastic connector with five metal 'fingers'. Just above that connector is a small, white, block with metal caps at both ends. That's a fuse which protects that battery connection. There should be another one like it near the main battery connector. There is a different looking fuse protecting the DC input (the yellow jack on the back panel of the laptop with a small plug at the end), which is inserted into the motherboard. Looking again at the same picture, I think that fuse is located just to the right of the mounting hole near the bottom right corner of the CPU socket. It looks slightly greenish in the picture. If it is the same as on the T23 motherboard, it's a 7A fuse. You can check it for continuity using the ohms position of a multimeter (should be 0 ohms).

[dinos_2006]

Many thanks Ray again ,

I removed the capacitor and checked the fuse .
Here are the results:
Putting the multimeter in the beep mode to test for short circuit
all the capacitors regardless of the probes position apper to be in short circuit. I suspect this is not normal. In addition I am completely lost in how to check if the board is working by putting only the mains power and the board supply only. That is , is there a way to check with the multimeter if the board is working by putting only the processor. The liittle green leds are not working again. The fuse is giving a reading of 0.02 Ohms. Any ideas about the capacitors or and what to expect as a sign of operation from my open thinkpad
Another photo with the capacitor removed
http://i111.photobucket.com/albums/n124 ... CN3578.jpg
and the power cord connected to the board.

Many thanks again for the time and effort.

[rkawakami]

Measuring capacitors with a multimeter not designed to measure capacitance is tricky. Polarized capacitors will act (measure) differently depending on how the meter leads are connected (red/positive and black/negative) to the part, what the resistance range is being used and how the capacitors are being used on the motherboard. If you are using the 'beep' mode that usually means the meter is in a diode measuring range and probably cannot be used to measure capacitors. Try the next-to-lowest resistance range on the meter (say 2K or 5K ohms). Put the red lead of the meter onto the + side of the capacitor and the black lead on the opposite side. You may get a brief flash on the multimeter display but it should eventually settle at "open" or "infinity". Reverse the meter leads (black on +, red on opposite side) and you should see a changing display. You may have to experiment with a higher resistance range to see this changing display. What is happening is that the capacitor is being charged by the voltage from the multimeter and thus affecting the 'resistance' being measured. If the measurements you make are opposite to what I just said, it only means the the multimeter is not following the same polarity standard that my meter is doing. What is important is that you see a changing resistance reading which starts out low and then increases in 'resistance' to some point which then remains stable. In any event, if you measure 0 ohms across capacitors (in any range and with either way of connecting the red/black leads), that means you have a short somewhere on the motherboard. In that case, you may have another capacitor that has shorted out or some other damage on the motherboard causing a short across the power lines.

(edit: Just re-read your previous post and missed answering this point...

...what to expect as a sign of operation from my open thinkpad

The only way I know of turning on the T2x series laptop with the keyboard removed is to use a port replicator (docking station) which has its own power button. If you don't have a port replicator then, as far as I know, you will have to install the keyboard onto the motherboard connector to be able to power on. However, before you do that, you may want to check the resistance between the center post of the DC jack and ground to see if there is a short. With my T22 I am reading around 570K ohms (one lead on the center pin and the other on any of the screws on the back port, serial, parallel or video). If you read anything significantly different then I would not plug in the AC adapter until you isolate the cause. This means checking the DC power jack, the I/O board and/or the motherboard for shorts if the resistance is much lower than 570K ohms, or opens (an blown fuse or broken wire) if the resistance is more than 570K ohms.)