25
Subject to change without notice
3 Error Diagnostics!
The following examples will help you to determine the board to be replaced or repaired. Due to each board’s comprehensive functions it is
not always possible to determine one board precisely. Thus it might be necessary to change more than one board.
As explained before under item 2, the power supply check has the highest priority.
STOP
Attention! It is recommended to reinstall the old board if a new board did not solve the problem.
Item
Behavior of the Instrument
Possible Reason / What to do
Remark
3-1.1
POWER LED not lit and no trace
visible on the screen.
Pull out fuse holder and check the (external accessible)
fuse. If the fuse is blown, replace it and switch the instru-
ment on again.
If the error is still present, and the (external accessible) fuse
is blown again, continue with item 3-1.3.
If the (external accessible) fuse is not blown, continue with
item 3-1.2.
T he ins tr ument mus t
be disconnected from
mains/line before che-
cking the fuse.
3-1.2
Remove the power supply shielding as described under
item B1.6 and check the (internal accessible) fuse on the
PS board. If the fuse is blown, replace it and switch the
instrument on again.
If the error is still present, and the (internal accessible) fuse
is blown again, continue with item 3-1.3.
T he ins tr ument mus t
be disconnected from
mains/line before che-
cking the fuse.
3-1.3
Replace the power supply as described under item 2.6 and
adjust the new power supply (see item 2.7 in chapt. Trou-
bleshooting).
3-1.4
Security check!
Check that after PS board replacement the protective earth
connection is re established.
Item
Behavior of the Instrument
Possible Reason / What to do
Remark
3-2.1
No trace visible on the screen.
POWER LED lit.
Release all pushbuttons (out) except the POWER pushbutton.
Set all knobs with an arrow marking to their calibrated de-
tent. Set HOLD OFF knob to x1 position. Set the other knobs
to midrange position.
If the trace is still not visible continue with item 3-2.2.
3-2.2
Press the CHI/II pushbutton to switch over for channel II
operation.
If the trace is not yet visible continue with item 3-2.6.
If the trace is visible, locate and identify the Y-POS. I poten-
tiometer centre connector on the soldering side of the FC
board. Measure 0 to +12 Volts dependent on the setting and
set it to +6 Volt.
If this can be achieved, continue with item 3-2.3
If the voltage cannot be set to values between approx. +3.5
and approx. +8.1 Volt (where the trace would be within the
graticule) continue with item 3-2.4.
3-2.3
As the Y position control voltage for channel I is present, the
absence of the trace in channel I mode must be caused by an
error in the channel I pre-amplifi er stage, channel mode con-
trol or channel switch. As all circuits are on YP board, replace
this board as described in Board Replacement section.
3-2.4
Replace the FC board as described in the Board Replace-
ment section.
H M 3 0 3 - 6 T r o u b l e s h o o t i n g
