From Dennis Tillman W7PF
"Then it occurred to me that a 7603 with the right amplifiers might work
just
as well as a 600 monitor. "
Wouldn't any dual channel plugin, like a 7A26 in both vertical and
horizontal slots also work. On the 7A26 and most other vertical plugins you
can set the two channels to "Add" and "Invert" channel 2. I haven't tried
it to display a 576 or 577 display, but I have used vertical plugins like
this for close to 50 years now.
Tom Bowers
On Sat, Jun 27, 2020 at 12:43 PM Dennis Tillman W7pF <dennis@...>
wrote:
Hi Thomas,
I added XY outputs to my 577 one day out of necessity when the HV
transformer failed so the CRT was dark. Walther Shawlee was the one who
suggested this as a temporary way I could continue using it until I found a
replacement HV transformer for it.
This post, #139493, explains what I did to work around the bad HV
transformer. It might give you some alternative ideas on how you can do
what you want.
Dennis Tillman W7pF
------------------------------------------------------------------------------
From: 'Dennis Tillman' dennis@... [TekScopes]
Sent: Thursday, September 07, 2017 9:32 PM
To: TekScopes@...
Subject: [TekScopes] How I made my 577 work without a HV transformer
Necessity is the mother of invention. I needed to measure some transistors
but the HV transformer on my 577 was dead so there was no CRT beam and
thus,
no display.
Walter Shawlee suggested I try connecting the horiz and vert output signals
from the 577 temporarily to one of the 600 monitors so I could start
testing
until the replacement HV transformer arrives. The 577 horizontal and
vertical signals are differential so I needed to have differential inputs
for each axis. I have a few of these 600 series monitors but none have
differential inputs (that was an extra cost option and, apparently, not
very
common).
Then it occurred to me that a 7603 with the right amplifiers might work
just
as well as a 600 monitor. I needed to provide the capability for
differential inputs for each axis on the 7603 (or any 7000 scope mainframe)
for this to work. A pair of 7A13 differential comparator plugins (designed
by Bill DeVey who also did the 1A5, 7B52 and 7b92 timebases, and the 81
Plug-In Adaptor) would have the required differential inputs I needed and,
fortunately for me, I had two working ones. So I stuck one in the vertical
slot and one in the horizontal slot of a 7603. Then I made a nice cable
(from standard four wire telephone cable), to connect the two instruments
together.
It worked perfectly. Now the 7603 displays the transistor curves as if it
was the top half of my 577. Every control (except for brightness and focus)
on the 577 still works exactly as it used to. The only tiny discrepancy is
there is no blanking to dim the trace when it is just a dot in the corner,
also, the 577 has blanking at the end of each current step that is missing.
I suppose if I really wanted to I could have added a fifth wire to the
cable
for the blanking signal but it really was not an issue.
Dennis Tillman W7PF
--
Dennis Tillman W7pF
TekScopes Moderator
