HP 1703A with No trigger ( HELP )
 

Hello All,
I just bought an HP 1703A Dual trace scope off E-Bay and sure
enough..it has problems.
Seems the only time the trace sweeps across the screeen is when I change
modes from Internal to External
Trigger. At first I thought it may be a dirty switch but cleaning didn't
help.

From what I understand...the trace is swept left to right by a "Sawtooth
Oscillator" that is synchronized to
peaks in the input waveform trying to be displayed (Channel A or B). Seems
this "Oscillator" is not resetting.
Instead it sweeps once then locks up till I "jog" it by changing modes. Then
it sweeps across ONCE and
then locks up AGAIN until I "jog" it. I've checked all the circuit board
edge connects, cleaned the rotary
switch that selects Normal/Delayed/External Trigger, tapped and wiggled
inside for lose connections
and yet no luck. Any chance someone has some hints or better yet a schematic
they could send my way?

Any and ALL help would be GREATLY appreciated.

Thanks....and a very best to all for the Holiday Season.

Cheers....Dean.