26
Subject to change without notice
3-2.6
Check the power supply output voltage as described from
item B1.1 to item B1.5 and continue with the following ins-
tructions in that section if an error is present.
If the power supply output voltages are OK, continue with
item 3-2.7.
3-2.7
Switch the oscilloscope off before continuing with item
3-2.8.
3-2.8
Remove the CR board plastic protection cover and make a
short between pin 2 (cathode) and pin 3 (grid 1).
See photo 3-2.8.
3-2.9
Switch the oscilloscope on and watch if the trace becomes
visible with very high intensity.
If the trace is not visible, switch the oscilloscope off, do not
remove the short and continue with item 3-2.10.
If the trace is visible, continue with item 3-2.16.
No potential difference
between cathode and grid
causes maximum beam
current in the cr t and
should be limited to a few
seconds.
3-2.10
Make additionally a short between crt pins 11 and 13 (both X
defl ection plates) and switch the oscilloscope on.
As no signal is applied at the INPUT CH I, a bright spot should
become visible in the screen centre.
If the spot is not visible switch the oscilloscope off, do not
remove both shorts and continue with item 3-2.11.
If the trace is visible, continue with item 3-2.19.
See photo 3-2.10.
No potential difference
between the X defl ection
plates means that the
beam is undeflected in
the horizontal centre, but
can still be off screen in
vertical (Y) direction.
3-2.11
Make an additional short on X Y board (soldering side)
between both wires from the Y fi nal amplifi er connected to
the crt Y defl ection plates and switch the oscilloscope on.
If even under these conditions no spot is visible although
the crt heater (fi lament) glows, cathode and grid 1, the X
defl ection and the Y defl ection plates are shorted, the crt
must be defective. Continue with item 3-2.23.
If the spot is visible switch the oscilloscope off, remove the
both shorts on CR board and the short on XY board. Continue
with item 3-2.12.
See photo 3-2.11.
H M 3 0 3 - 6 T r o u b l e s h o o t i n g
Item
Behavior of the Instrument
Possible Reason / What to do
Remark
photo 3-2.8
photo 3-2.10
photo 3-2.11
