Electronics > Beginners
Pulsing Vacuum Fluorescent Display
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Electro_Jr:
Hey Guys,
Hope someone can help me out I have a Sony DXA-H2750 stereo that I am working on.  The display has a pulse to it in the lower left corner of the display and appears dim overall. 

Checking it with a scope pin1 has 6V @60hz  and pin 39 has 6V 0HZ.  This has me stumped because pin 1 and pin 39 (Fla1, Fla2) are wired together in the transformer (PG 28 of the service manual)

Having never worked with a Vacuum Display before I'm a little lost.   
I have attached pages from the service manual 3 pages of information for the VFD and Transformer. (Couldn't upload the full 40 pages service manual it was too large)

Does pins 1,39 (FLA1 FLA2) provide the positive voltage, and the controller provide the negative, which causes the electrons to be drawn across the phosphor and fluoresce?

Should pin 1 and 39 have matching voltages/frequencies?  What voltages should I see at pin 1 and 39? 

Am I looking at the wrong spot for this pulsing?   

Thanks for any help provided. 


Electro_Jr:
Uhg....that pdf turned out horrible.   Let me see if I can't get you guys some better files. 
Ok. JPG it will be today.
stj:
i really hate japanese engineers,
they treat schematics like some kind of copy-protection device!
what a disgusting rats nest.  :wtf:

from what i can see your display heater is driven by some type of booster circuit - over complex as usual.
that's another thing i hate about japanese designers - they would rather use 100 discrete parts than a simple dedicated i.c. for anything!  |O
james_s:
I fixed an old Russian VFD clock that had a severe flicker. The problem turned out to be a bad electrolytic capacitor filtering the ~30V supply to the panel.
sarahMCML:
Hi,

It looks to me that the VFD filament lines FLA1 and FLA2 are driven by the second from the bottom winding on the transformer board, therefore A.C., biased to a DC potential of around +6V DC by Zener D944 connected to FLA2.

Regards,
Sarah.
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