Electronics > Beginners
Pulsing Vacuum Fluorescent Display
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james_s:
A bad filter capacitor for example would stop doing its job, so instead of smooth DC you would see ripple which would be indicated as an AC voltage on a meter. If you're supposed to have say 24VDC and the meter shows a few Volts of AC then you know you have a lot of ripple.
sarahMCML:
Hi,

What ripple voltage do you see across points FLA2, and also FL30V, with respect to 0V, using your scope when set to A.C. mode? Hopefully just relatively small values. Also, does FL30V measure about 36V, as it says on the schematic?

Regards,

Sarah.
Electro_Jr:
FLV30 is showing about 37 Volts.   With no ripple. 

FLA2 is showing no ripple either. 

I did realize that I am reading the scope wrong FLA1 has 9.86V  Vmax 5.23 Vmin -4.65V.     

sarahMCML:
Hi again,


--- Quote from: Electro_Jr on November 26, 2018, 10:44:58 pm ---FLV30 is showing about 37 Volts.   With no ripple. 

FLA2 is showing no ripple either. 

I did realize that I am reading the scope wrong FLA1 has 9.86V  Vmax 5.23 Vmin -4.65V.   

--- End quote ---

Is the reading of FLA1 of 9.86V a DC or an AC voltage, and to what is it referenced, 0V or FLA2?
And what are the meanings of the other two values: surely Vmin isn't really going negative of 0V?

Regards,

Sarah.
Electro_Jr:
Its this crazy scope or the crazy operator.  With it setting on AC mode it is showing those +/- voltages.  With it on Dc mode its shows +~10V to 0V.   
This was reading FLA1 referenced to ground.   

The FLV30 is showing nothing on AC mode but 37V on Dc mode referenced to ground.
FLA2 is showing nothing on Ac mode but 6V on Dc mode referenced to ground.


I did make an observation when measuring FLA1 setting the trigger voltage to 0 Volts setting the scope to read Ac with a ground reference.  Every time scope triggers it flashes an led.  The pulsing of the led matches that of the display. 
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