Re: 475 Triggering Issue -- Will recent 468 Triggering Issue Thread Help Me?


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.


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