dell,monitor,repair

[gerry myles]

I have a Dell E173FPb monitor with standbye light flashing on/off.No service manual available .Pulled it apart and found a shorted 2sc5707 Q739 could find no other faults it fired up for 2 minutes there are 2 pairs of these transistors so i replaced the four of them and it fired up for 20 minutes and one pair has gone again.Can anyone help.Gerry