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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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No horizontal sweep on NEC FE1250
Hi,
I've got a NEC FE1250 (JC22W71) 22" monitor which display a vertical line only. This is due to a blown R556. The point is I can't figure out why this resistor keeps on blowing. There is a service bulletin from NEC that states: The result of cause investigation to which R556 becomes open, it turns out that IC541 which is power regulator for IC501 is operating incorrectly. It is thought that IC541 has received damage, point of bonding wire inside of IC has stress with over heat or abnormal welding conditions. I replaced the parts as described in the bulletin, but the results so far are that the monitor will operate ok for a while, but then R556 blows again. Any suggestions are welcome. Thanks, Reinhard |
#2
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It can be that the IC is being damaged from something, and thus blowing the
resistor. Check to see if the main power supply is in specs. If it is over voltage this can cause the problem you are having. Also, if something is pulling too much current on the load side of the resistor, it will be damaged, including other components in the path of the load. In simple terms, you will have to replace the damaged parts, and also look for the cause of these failures. -- Jerry G. ========================== "Reinhard" wrote in message ... Hi, I've got a NEC FE1250 (JC22W71) 22" monitor which display a vertical line only. This is due to a blown R556. The point is I can't figure out why this resistor keeps on blowing. There is a service bulletin from NEC that states: The result of cause investigation to which R556 becomes open, it turns out that IC541 which is power regulator for IC501 is operating incorrectly. It is thought that IC541 has received damage, point of bonding wire inside of IC has stress with over heat or abnormal welding conditions. I replaced the parts as described in the bulletin, but the results so far are that the monitor will operate ok for a while, but then R556 blows again. Any suggestions are welcome. Thanks, Reinhard |
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