PRONET 8 PORT Network Switch Repaired
On call of one of my customers I have visited his place on complaint that they are not able to open shared files in any of the computers. They are using 5 nos. of desktop computers in their office. I looked to the switch there was no power LED Indication that means no power. Hence I have checked the power adapter and it had 9V DC output which means good. Now this also means the problem is with the 8 port switch itself. Once the switch was opened I did not see any physical damage or burnt marks on PCB.
Then I have started some troubleshooting with the help of my multimeter. Since there was 9 Vdc so I checked on the surrounding components with diode check range to find out if there is any Open or Short Circuit Components and all components seem to be good.
Next I have to find out if any component gets over heated after applying a voltage. Hence I have connected power adapter and by touching with finger randomly on PCB I found 8 PIN IC 34063A is getting hot.
Now I have unplugged the power adapter and tested the IC with multimeter for short circuit but there is no positive sign of short circuit. Hence I have decided to replace the IC and check. I have arranged the IC from the component shop and replaced in place of suspected IC.
This IC is used for DC-to-DC Converter Control.
Little bit complicated to remove this type of IC on suspect for testing from Multilayer PCB as you see in the photo above I have damaged some pins of the old IC while removing .
Note: Please use Good quality of flux while removing old solder. First apply the flux on solder joint then re solder the joint and then proceed for Desoldering.
After the replacement of IC I have re-plugged the power adapter and Power On, and the LED indicator was glowing. That means the unit is ready for use now.
I have forgotten to take voltages of old IC but I have marked the voltages on above Block diagram with New IC.
This article was prepared for you by Yogesh Panchal who works as a Computer Hardware Engineer in Mumbai India.
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