Tek 465 Sweep Problem

[nanu]

Hello Group,

I have a Tek 465 s/n B3234XX Opt. XB which works perfectly
except for the following: On the 3 slowest sweep speeds there is no
apparent trace on the screen. However if I push the beam finder button
I can see a clear indication of swept trace at the correct speed.
This is only at the the 3 slowest positions all other sweep speeds
behave normally. It seems that the trace is being blanked at the 3
slowest speeds? Anybody ever see this before? BTW I can't seem to find
my manual, so I may have to buy a new one.

Thanks
Gary

 

[Jim Yanik]

nanu <nanu37@yahoo.com> wrote in news:0FCgPx78XREyqoxYwxdlk2KZZ4WB@4ax.com:

Hello Group,

I have a Tek 465 s/n B3234XX Opt. XB which works perfectly
except for the following: On the 3 slowest sweep speeds there is no
apparent trace on the screen. However if I push the beam finder button
I can see a clear indication of swept trace at the correct speed.
This is only at the the 3 slowest positions all other sweep speeds
behave normally. It seems that the trace is being blanked at the 3
slowest speeds? Anybody ever see this before? BTW I can't seem to find
my manual, so I may have to buy a new one.

Thanks
Gary

Some scopes had circuitry to -reduce- trace intensity at slow sweeps to
prevent burning the CRT phosphor.I can't recall if the 465 had it.(at slow
sweep speeds,all you have is a slow moving bright spot going across the
graticule.)

Can you increase intensity to where you can see the sweep?(without using
beamfind),Or adjust CRT bias to see it?

Other than that,you will need to check the sweep blanking circuit
schematic.

Not too many people even USE the slowest sweeps speeds. ;-)
[5sec/div,2sec,1sec.]

--
Jim Yanik,NRA member
jyanik-at-kua.net