help - 11/34 console problem -- first LA output

[Gooijen, Henk]

Tony wrote: 

> > 
> > Making your own pod...! Again, points earned Tony!  Chapeau! :-)
> 
> Well, back when I got that instrument, _any_ LA was 
> expensive. The only way I could afford one was to get one 
> missing the pods. And I'd done a fair amount of ECL work for 
> my Ph.D, so when I found the inputs were actually 
> differential ECL signals, it didn;t worry me too much. 
> 
> -tony

Ah. Ok then. I never worked with ECL, so that is totally
unknown territory for me.  You had a jump start then :-)

I continued working on the 11/34 console board. Made a few new
measurements (display and keypad). I am still figuring out what
I have seen. I am a bit reluctant to remove an IC from the board,
put in a socket and a new IC, just to find out that I overlooked
something and the replaced IC was not bad.

I have the impression that the strobe pulse to latch the 74175
that outputs the 3-bit code to the 7447 display driver is issued
at a way to low rate. I seldom see this pulse, but expect it to
see quite often as it must for multiplexing the display ...
To support this repair I will write up a webpage with the LA
pictures. I will mention the URL here. Very soon ...

  thanks for all input so far,
- Henk, PA8PDP.

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