Sunday, July 24, 2011

Viewsonic VG1930WM no power, repaired

I just finished repairing a Viewsonic VG1930WM that had no power, no standby LED, completely dead. I opened up the monitor and checked the output voltages from the power supply and both were present and stable. I verified that the 5V was still present at the main board. Next I checked the output from the 3.3V and 1.8V linear voltage regulator ICs on the main board and the 3.3V regulator's output was considerably low around 2.2V, the output from the 1.8V regulator was also very low but it gets its input from the 3.3V regulator so it makes sense that the 1.8V regulators voltage was low. I replaced the 3.3V regulator after verifying it was faulty and the monitor was still dead when I plugged it in to check voltages again, the 3.3V regulator's output was now within tolerance so I again checked the output from the 1.8V regulator and it was still low about 1.2V, so I then replaced the 1.8V regulator and when I plugged the monitor in to check the output from the 1.8V regulator I saw the standby light turn on, the voltage output from the 1.8V regulator was now within tolerance and the monitor turned on and functioned flawlessly.




Professional Repair: If you are interested in having your power supply board repaired professionally then you may be interested in our mail in repair services. We can do the repair on this particular power supply for $50 plus the cost of return shipping and handling. Click here to see our mail in repair service page. You can also email contactus@preher-tech.com for more information.

Also don't forget to visit http://www.preher-tech.com

Viewsonic VX910 no power, repaired

Recently did a repair on a Viewsonic VX910 that had no power, no standby LED, totally dead. Upon opening the monitor I could see that someone had already replaced all the electrolytic capacitors in the output filter circuitry, but for this type of failure I normally don't suspect the filter capacitors anyways. I plugged the monitor in to check for any output voltages from the PSU and I could here a faint chirping coming from the power supply, this is always a good indication of a shorted output diode or faulty components in the feedback circuitry, the power supply is continually trying to start up and then shutting down,over and over. As I suspected there was no output from the power supply. I pulled the power supply and the first thing I checked was the dual schotttky diode D660 and one of the diodes in the dual package was shorted. The original diode was a MBR10100CT dual schottky diode, I replaced it with a B20100G dual schottky diode. After replacing the dual diode the monitor powered on and worked once again.







Professional Repair: If you are interested in having your power supply board repaired professionally then you may be interested in our mail in repair services. We can do the repair on this particular power supply for $50 plus the cost of return shipping and handling. Click here to see our mail in repair service page. You can also email contactus@preher-tech.com for more information.


Also don't forget to visit http://www.preher-tech.com