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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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Compaq TFT450 No Power
Hi,
I have a compaq TFT450 lcd monitor which won't power up. The input fuses on the 5v and 12v inputs are fine. After the each fuse there is a 470 micro farad capacitor. I have a multi-meter but I am not too sure on how to test the capacitors ? If anyone has any pointers, hints or tips on what to look for please let me know. Regards Dave K. |
#2
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Compaq TFT450 No Power
I have a compaq TFT450 lcd monitor which won't power up. The input
fuses on the 5v and 12v inputs are fine. After the each fuse there is a 470 micro farad capacitor. I have a multi-meter but I am not too sure on how to test the capacitors ? To test the capacitors you will need an ESR meter. It is very well possible that one or more electrolytic capacitors are bad. Coincedently I repaired a Compaq TFT screen yesterday (randomly flashing lines); while tracking down the cause of the problem I did notice that many of the SMD caps did have a poor ESR. In this case the problem was caused by a bad electrolytic cap near the power input. -- Peter van Merkerk peter.van.merkerk(at)dse.nl |
#3
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Compaq TFT450 No Power
Peter van Merkerk wrote:
I have a compaq TFT450 lcd monitor which won't power up. The input fuses on the 5v and 12v inputs are fine. After the each fuse there is a 470 micro farad capacitor. I have a multi-meter but I am not too sure on how to test the capacitors ? To test the capacitors you will need an ESR meter. An alternative for using an ESR meter is to use a oscilloscope to watch the signal over the capacitor when the device is powered on. If the capacitor is good you should see no or only a very small signal. -- Peter van Merkerk peter.van.merkerk(at)dse.nl |
#4
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Compaq TFT450 No Power
Hi Peter,
I think that its the two surface mount capacitors near the fuse terminals. Is it simply the case of removing them by de-soldering the two contact points on either side of the caps ? Regards Dave K. "Peter van Merkerk" wrote in message ... Peter van Merkerk wrote: I have a compaq TFT450 lcd monitor which won't power up. The input fuses on the 5v and 12v inputs are fine. After the each fuse there is a 470 micro farad capacitor. I have a multi-meter but I am not too sure on how to test the capacitors ? To test the capacitors you will need an ESR meter. An alternative for using an ESR meter is to use a oscilloscope to watch the signal over the capacitor when the device is powered on. If the capacitor is good you should see no or only a very small signal. -- Peter van Merkerk peter.van.merkerk(at)dse.nl |
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