DECCA 70 SERIES CHASSIS

You are here:
< Back

The problem is incorrect field lock at switch on. Repeated
channel changes will produce correct field lock, alterna-
tively retuning a channel will bring the picture to the
correct position. When a channel change is made however
the picture is split. The field timebase and If. i.c.s have
been replaced with no improvement and the voltages in
these areas are roughly correct. The a.g.c. action seems to
be correct.
This sort of problem is generally due to faulty
electrolytics. The suspects in this case are C307 (10µF) in
the field sync pulse integrator stage and the two
electrolytics 1C11 (1µF) and 1C12 (33µF) associated with
the a.g.c. circuitry. An oscilloscope to check the quality of
the field sync pulses at the base of the video emitter –
follower 1Tr1 would be invaluable.

Table of Contents

Leave a comment

I have read the privacy policy and accept
Read our privacy policy

This form collects your name, email and content so that we can keep track of the comments placed on the website. For more info check our privacy policy where you will get more info on where, how and why we store your data.

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