HANG ON.... HOLD THE PHONE
Ch1 Position knob DOES HAVE AN EFFECT
it would appear that if the position knob
As per Photo 27
if it's set all the way to the right THE CIRCLE IS SMALLER
As per Photo 28
if it's set all the way to the right THE CIRCLE IS BIGGER
but if the position knob does not affect the vertical movement in any way
Hmmm. Try changing the positions of the vertical mode switches (ADD/CHOP/ALT and CH1/CH2/BOTH) to see if there is any change. Also, disable the signal to CH1/X temporarily and verify that whatever fragment of circle you have is due to that signal. I think you have a channel switching problem of some sort, although I'm not sure what. Check the XY and (not)XY signal as I said before and then start looking at everything they control. I can't see how the CH1 position control would have that effect (or any) unless CH1 is not getting fully disconnected from the vertical amplifier when commanded. And since any such issues would cause big problems in other modes, this particular issue (but perhaps not all of them) is likely related to the control of U130 by the XY logic line through S550, U540 and related nearby parts.
I CONDUCTED A VERY THOROUGH TEST ON ALL THE BUTTONS AND KNOBS AND SWITCHES
The Results are as follows
For testing purposes i have set both SIG GEN Channels to
Sine Wave
1Hz
2V
===================================================
MAIN CONTROLS
===================================================
INTENSITY - Works as Expected and Adjusted
TRACE ROTATION - Works as Expected and Adjusted
BEAM FIND - Works as Expected
PROBE ADJUST - Works as Expected
FOCUS - Works as Expected and Adjusted
POWER - Works as Expected and Powered ON
===================================================
VERTICAL CONTROLS
===================================================
============================================================================
NOTES :
CH1 Initially set to 1 Volt/Div
CH2 Initially set to 1 Volt/Div
Timebase set to 1ms/Div (Freq 1kHz)
Trace position without any input is set to to the 0V Midline
Changed BOTH Sig Gen Channels to 1kHz for calibration of amplitude.
Calibrated with a Square wave of 2 V Peak to peak
Then Tested basic signal input of the following waves.
- Sine
- Square
- Triangle
- DC
Performed on Both Channels
Both Channels PASSED
============================================================================
-----------------------------
VERTICAL MODE CONTROLS
-----------------------------
Switch (CH1 / BOTH / CH2)
CH1 - Works as Expected
BOTH - Works as Expected
CH2 - Works as Expected
-----------------------------
Button (BW LIMIT 10MHz) - Works as Expected
Button (CH2 Invert) - Works as Expected
-----------------------------
Switch (ADD / ALT / CHOP)
ADD - Works as Expected
ALT - Works as Expected
CHOP - Works as Expected
-----------------------------
-----------------------------
CHANNEL 1 CONTROLS
-----------------------------
CH1 POSITION KNOB - Works as Expected
CH1 VOLTS/DIV DIAL - Works as Expected
Tested with 1V, 2V, 3V, 4V, 5V
Stops at each level at the correct level
CH1 CAL AJDUSTMENT - Works as Expected
SWITCH (AC GND DC)
AC - Works as Expected
GND - Works as Expected
DC - Works as Expected
-----------------------------
-----------------------------
CHANNEL 2 CONTROLS
-----------------------------
CH2 POSITION KNOB - Works as Expected
CH2 VOLTS/DIV DIAL - Works as Expected
Tested with 1V, 2V, 3V, 4V, 5V
CH2 CAL AJDUSTMENT - Works as Expected
SWITCH (AC GND DC)
AC - Works as Expected
GND - Works as Expected
DC - Works as Expected
-----------------------------
===================================================
HORIZONTAL CONTROLS
===================================================
-----------------------------
HORIZONTAL MODE CONTROLS
-----------------------------
Switch (NO DLY / INTENS / DLY'D)
NO DLY - Works as Expected
INTENS - Works as Expected
DLY'D - Works as Expected
-----------------------------
-----------------------------
HORIZONTAL CONTROL
-----------------------------
HORIZONTAL POSITION KNOB - Works as Expected
HORIZONTAL SEC/DIV DIAL - Works as Expected
X10 CAL AJDUSTMENT (PULL AND ADJUST) - Works as Expected
DELAY TIME
SWITCH 0.4ms 20us 1.0us
0.4ms - Works as Expected
20us - Works as Expected
1.0us - Works as Expected
Multiplier Knob
< x1 to >x50
- Works as Expected
-----------------------------
===================================================
TRIGGER CONTROLS
===================================================
VAR HOLDOFF KNOB
Norm (Anti clockwise) to Max (Clockwise) - Works as Expected
BUTTON SGL SWP reset button - Works as Expected
BUTTON P.P AUTO - Works as Expected
BUTTON NORM - Blanks the Screen
BUTTON SLOPE - Works as Expected
LEVEL KNOB - Works as Expected
INT SWITCH
CH1 - Works as Expected
VERT MODE - Works as Expected
CH2 - Works as Expected
SOURCE SWITCH
INT - Works as Expected
LINE - Works as Expected
EXT - Works as Expected
EXT COUPLING SWITCH
AC
DC
DC / 10
DID NOT TEST, NOT RELEVANT
=====================================================
ENTERING XY MODE
SIG GEN 1
Sine Wave
1000Hz
2V
SIG GEN 2
Sine Wave
1001Hz
2V
Changed only Time Base to XY Mode
RESULT
- NO DISPLAY ON SCREEN
(Horizontal Position Adjustment needed)
- Horizontal Position Adjusted to the centre line
- Amplitude is correct
- However there is no immediate circle or Diagonal Line
TESTED ON ANOTHER SCOPE "Entering XY Mode" as above.
My Kikusui scope on the same settings IMMEDIATELY IN XY Mode
had the full circle in the centre without adjustment needed
when changed to YT Mode, Diagonal Line appeared.
that doesn't happen on this scope
From this position
- REMOVED CHANNEL 1 SIGNAL CABLE
no change - 2V Vertical signal remains
REPLACED Ch1 Cable
- REMOVED CHANNEL 2 SIGNAL CABLE
- 2V Vertical signal disappears and becomes a single dot
Those results occur regardless of whether the switch is in
CH1 , Both, Ch2 Mode
FROM HERE
Channel 2 Dial reacts and changes the amplitude accordingly
Channel 1 - I need to change from 1V/Div to at least 100mV/Div
Before i can see only a small semicircle
If i change from 100mV/Div to 50mV/Div the Semi Circle shoots out
disproportionately to the voltage change.
at 100mV the semi circle extends out by 1/2 a Division
at 50mV the semi circle extends out beyond 5 divisions, specifically 9.5 divisions
None of this was required on my working Kikusui scope.
So it would appear
- The Main controls seem to work
- Ch 1 controls seem to work correctly
- Ch 2 controls seem to work correctly
- the scaling seems to work and be on par and correct
- Trigger controls seem to work
- The front end inputs seem to work
- the selector for Ch1 , 2 and Both seem to work perfectly
the problem only seems to occur when entering XY Mode
and when an input is removed, there is no Horizontal line
and there is an obvious offset of 5 divisions to the left