Tektronix Type 547 channel B not triggering

[The Guy]

Hi all...

I decided to continue tackling the repair of my beautiful tek 547 oscilloscope. It is working quite well... but it still has a few problems.

The main issue right now is that channel B trigger circuit seems to be not working at all, no matter what the settings or the circuit pots adjustment are the trace seems unaffected.

I´ve been reading and some fellas that had the same problem ended up discovering that the faulty component was one of those tunnel diodes, but i checked them out and compared the readings with the ones from channel A and they read the same.

 I am a complete noob regarding triggering circuits... so not sure where or how to start. Any suggestions?

Thanks a bunch.

[rajeshvs]

way too late reply still if it helps, check this -

https://lazyelectrons.wordpress.com/2018/07/06/tektronix-547-oscilloscope-restoration/

Could be the tunnel

[KE5FX]

Some very nice work on the 547, definitely.   Have you found that a lot of the carbon-comp resistors have drifted upward in value?  I'm curious as to when that phenomenon started.... it seems that the oldest resistors fare better over time than the newer ones from the 1970s-1980s in many cases.

[rajeshvs]

I did not  find a resistor drifted too much in a Tektronix. All the 3  Teks I have worked never had a  resistor with bad tolerance, or they were not bad enough to catch my attention or create  trouble to me .  But they all were from 60s, before the window you mentioned, So guess your assumption is correct.

I did a 549 Analog Storage - https://lazyelectrons.wordpress.com/2018/01/11/tektronix-549-restoration/

and a RM35A(535A)  too - https://lazyelectrons.wordpress.com/2018/03/14/tektronix-rm35-rescue/