THORN 9000 CHASSIS

< Back

The trouble with this set is that R725 and R735 have
overheated to such an extent that the values cannot be read,
while fuse F4 has blown.
It’s difficult to relate these faults, unless the thick film unit
has failed with the result that the trip circuit is not
operating. R725 (1801(52) simply forward biases the beam
limiter diode W722. F4 protects the 24V supply to the field
timebase and, via R735 (3.9Q), the signals panel. Either of
the two decoupling electrolytics C171 and C196 on the
signals panel could be leaking. If C196 is a tantalum type it
should be changed to an aluminium type. The voltage at F4
can rise excessively if there’s a fault in the field timebase: in
this event, connect a 12052 5W resistor from F4 to chassis
and check the field timebase circuit.

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.