THORN 2000 CHASSIS

< Back

This set has given several years trouble free viewing. It’s
now developed the following fault however. Every few
minutes the colours unlock, forming not so much Hanover
blinds as Venetian blinds. The trouble can be temporarily
cured by pushing lightly on the push-button tuner for the
particular station. The tuner has been repaired, so I assume
it’s a decoder fault.
Decoder problems with the 2000 chassis are quite rare.
From your description, it seems that the reference oscillator
is drifting off lock. Suspect components are the electrolytics
C3 and C7 (both 4,0) in the burst gate/amplifier circuit,
the 0A91 diodes (W1-4) in the burst detector circuit, the
BC107 d.c. amplifier transistor VT3, and the crystal. Since
these components are inexpensive, we’d replace the lot then
adjust R13 (detector balance) and R15 (oscillator
frequency) as described in the manual.

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.