That's cool -- we'll 'resurrect' the thread when you returnThanks for yr interventions... i'll post asap, but itcan be quite a while.
. Is the calibration signal 0,5 V; 0.5V/div;20mS/div; I have no sinus generator....Can you input a sine wave and post a photo of what the oscilloscope screen looks like?
Looks like a resistor gone high in the amplifier for the X plates, either that or in the shift control.
That usually means said components are located 'off board' (e.g. panel/chasis mounted controls and components mounted to same, etc...)R66 and a few others etc aremarked with an asterix on the diagram which means they are not present on the PCB....!? I dont get that
While that probably 'exonerates' the tube (i.e. rules out loose electrodes) it, nonetheless, should be possible to illuminate the extreme right side given sufficient x-axis input amplitude...On EXT X mode (pulling knob at center of time/div) the signal occupies up to 4/5ths of the display. Without EXT X it is only 1/3th; the same for CHAN 2;
I'm not sure how it works on a scope, but basically it imposes a small bias on one deflection plate and subtracts the same amount from the other plate.@ian field: Can you explain "shift control" ?
To clarify: In general, when such an instrument is set for 'External X-axis input' (AKA "X-Y" or "X,Y" mode) one channel will process the vertical (Y-axis) input signal whereas the other will process the Horizontal (X-axis) input signal...Hello thanks fr yr answ. What do you mean by max gain: I have from 5V/ div to 10mV/div; do you mean in this case 10mV/div; I only have a trafo generating 25V at hand (measured with voltmeter). I have tried with 25V AC and 10mV/div; horizontally nothing changes;
I also tried to augment the 'trace length' with another potmeter (R77)(on sweep generator). It helped a bit (20%) but not more at the end of the potmeter turns. In the last case the display is used for 50%. (not EXTENDED X)
Correct -- Max gain=most sensitive range...I have from 5V/ div to 10mV/div; do you mean in this case 10mV/div
At a setting of 10mV Per division, 25V RMS (i.e. > 70v P-P) should produce more than 700 times the deflection required to 'reach' both 'sides'...I only have a trafo generating 25V at hand (measured with voltmeter). I have tried with 25V AC and 10mV/div; horizontally nothing changes;
The gorilla is a bit excessive - an angle grinder maybe?To clarify: In general, when such an instrument is set for 'External X-axis input' (AKA "X-Y" or "X,Y" mode) one channel will process the vertical (Y-axis) input signal whereas the other will process the Horizontal (X-axis) input signal...
Correct -- Max gain=most sensitive range...
At a setting of 10mV Per division, 25V RMS (i.e. > 70v P-P) should produce more than 700 times the deflection required to 'reach' both 'sides'...
OK... This is going to sound a bit 'goofy' -- But I hope you'll give it a try all the same
1) Set the scope for display of the calibrate signal in such manner that it would, were the instrument properly functioning, give a full-width display...
2) Carefully - Physically invert the instrument while gently shaking same -- note any changes in the display...
Rationale: Inasmuch as we have investigated the 'usual electrical suspects' I am attempting to eliminate loose or 'open' electrodes (Spec. deflection plates and connections thereto) as possible 'culprits'...
Note -- There remains much more to be investigated on the electrical/electronics 'front'! -- I am merely attempting to 'rule out' "800 lbs gorillas" - as it were!
Best regards
HP
That's what I get for mixing metaphors -- 'elephants in the room' might have been more apropos even if less 'dramatic'/'comic'The gorilla is a bit excessive - an angle grinder maybe?
Ok -- based upon that and other observations I feel we may safely assume the tube is in good conditionNo change on shaking gently. I can also turn the tube on its long axis. No deformation of the signal either.
by Jake Hertz
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by Jake Hertz
by Jake Hertz