84 Magnavox console TV

[Alex KL-1]

Originally Posted by liammc00

Did some DC mesmurmnts on the video IF IC and I got some concerning results

Here they are
PIN 14 should be between 7.6-11.5 volts I'm reading 6.7volts IF AGC . PIN 14 splits between a 6.8kohm resistor and a .0027 cap which then goes to ground. After the 6.8kohm resistor it goes to a .047 cap and then to ground.
PIN 12 should be 5 volts I'm getting 3.7 with a full image on screen and 3.3 with no image this pin goes out and spilt between the sound IF and then goes to video buffer transistor Q153 on the collector is 6.6v, the base is 3.3v, and the collector is 2.6volts. the voltages should read base 4.8v and emitter 4.3v. after this transistor it goes to a .001 cap then to 1k ohm resistor then to splits between C175 which is a 39pf cap and L154 to ground. After C175 it spitls again between C176 82pf and L177 to ground. Finally it enters pin 13 chroma input of the chroma and luma processer IC. I don't know if this would case a B/W picture but I thought I would check.

Is not very common, but I see one time or another semiconductors damaged by the flyback sparks (especially IC), even at some distance (due to EMP). Last time it occured to me was with a Toshiba TV that made a lot of sparks due to bad HV connector plus a lot of dirt. A IF IC died.