KB SV048

< Back

The first fault was no picture or sound. The PCF802 line
oscillator valve together with its cathode resistor RI49 and
the tuning capacitor in the cathode circuit CI27 (R149 had
gone low resistance and was burnt) were replaced, restoring
the picture and sound, and the oscillator coil was then
adjusted for a steady picture. The trouble now is line jitter.
The other tuning capacitor C126, the coupling capacitor to
the output stage (C129) and the sync separator transistor
have been replaced without success.
First look for a dry -joint on the printed board, then try
replacing the oscillator feedback capacitor C 125 and if
necessary the flywheel line sync discriminator diodes
D7/D8. If this does not clear the fault it is likely that one of
the polystyrene capacitors C115 -C119 inclusive in the
flywheel line sync discriminator circuit is defective. We
usually replace the lot in such cases. (ITT VC200 chassis.)

Previous KB LFT50
Next KB VC1 CHASSIS
Table of Contents
0 0 vote
Article Rating
Subscribe
Notify of
guest

This site uses Akismet to reduce spam. Learn how your comment data is processed.

0 Comments
Inline Feedbacks
View all comments
0
Would love your thoughts, please comment.x
()
x