The 475 trigger pickoff circuit is significantly different than the
468 circuit. From your description, something is wrong with or around
U370 on schematic 3. Take a close look at R403 which if open would
affect triggering of both channels.
X-Y mode and the channel 2 vertical signal out on the rear of the
oscilloscope also depend on biasing from R403 so checking those
functions may provide more information.
On Fri, 25 Jan 2013 20:46:14 -0000, "stan_katz" <stan_katz@...>
I have an ancient 475 scope which works fine with an external trigger, but will not trigger on any of the internal sources. Should I start by reviewing the recent 468 triggering issue thread to get me going? If not, can anyone recommend a thread I should start with? Of course, I'd be delighted to receive help on this thread.