Pilot tv brightness issue

[jr_tech]

Did you disconnect at least one end of the diode, or is it still “in circuit” ?

What are you reading each direction?

jr

[timmy]

Originally Posted by jr_tech

Did you disconnect at least one end of the diode, or is it still “in circuit” ?

What are you reading each direction?

jr

Out of circuit, Meg ohms one way and k ohms the other. I remember I had got 2 different kinds of 1n34 diodes when I restored this set,one had a red cathode end and the other a black cathode end so I just changed that diode to the black since I had the red one in there and the pic is better . But I do remember that someone had started the restoration and they used ceramics for hv filters and horizontal couplings and since finishing the set the picture flickers in different ways on scene changes so I'm thinking those caps have to go. The verticle couplings are correct. I believe the horiz ceramics used in here are doubled up for the capacitance changes when warmed up but they still may be creating problems.

[jr_tech]

On all digital meters that I have seen, the diode test mode measures the voltage drop across the diode in forward and reverse direction (when the leads are reversed). The foreword drop through a germanium diode is usually around 0.3 volts and “OL” in the reverse direction.

Your readings, IMHO, are inconclusive but I would expect more resistance than megohms (usually OL) in the reverse direction. Do you have a new 1N34 to test?

All of the HV caps in my set are ceramic, but higher than spec value...no problem. I suspect that your poor sync (flipping) is likely caused by the weak video signal... when you get decent contrast, sync should improve.

jr