HP1740A Option 101

[Andrew Holme]

I wish to reverse option 101 on my HP1740A 'scope to restore the standard
A-vs-B functionality. Refer to section 4-107 in the service manual for
details.

I think I've identified the components involved, but I'm slightly worried
about a discrepancy between my 'scope and the manual:

C77, CR28, Q21, R139 and R140 on board A3 shouldn't be there, but they are!
The manual says they're omitted for option 101. Maybe HP decided it was
simpler just to fit them to every board; or, maybe I've got the wrong
version of the service manual?

Can anyone throw any light on this before I start cutting wires?

 

[Andrew Holme]

Andrew Holme wrote:

I wish to reverse option 101 on my HP1740A 'scope to restore the
standard A-vs-B functionality. Refer to section 4-107 in the service
manual for details.

I think I've identified the components involved, but I'm slightly
worried about a discrepancy between my 'scope and the manual:

C77, CR28, Q21, R139 and R140 on board A3 shouldn't be there, but
they are! The manual says they're omitted for option 101. Maybe HP
decided it was simpler just to fit them to every board; or, maybe
I've got the wrong version of the service manual?

Can anyone throw any light on this before I start cutting wires?

It worked: I have X-Y mode. They must fit those parts to every board.

Now to try that Lorenz attractor circuit ...