How is startup drive derived?
Various models of TVs and monitors use different techniques: multivibrator, deflection chip powered from standby supply, high value resistor supplies current to horizontal driver or HOT directly, etc. For this TV, a single chip is used for sync and deflection, a TDA8305 – TV Signal Processor. However, after examining every pin on this chip, it is apparent that there is no DC power available until after the set starts up and the flyback supply is running. The supply voltages for the chip are all 13 V – rectified, filtered, and regulated off of a winding on the flyback. This leaves only one possibility – there is a high value resistor between the 130 V B+ and the base of the horizontal driver transistor. The collector of the horizontal driver transistor has the expected +130 V B+ so the transistor is not turning on or is open (not likely). First, I unsolder the base of the horizontal driver transistor so I can check the junctions with an ohmmeter – it appears good. Better make sure to re
