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#216189 - 13/05/2004 20:54 Dead VFD?
maczrool
pooh-bah

Registered: 13/01/2002
Posts: 1649
Loc: Louisiana, USA
We have a dead display here. Does anyone know where the 60 volts is generated on the VFD? Is it internal or some from something on the display board? It is missing from this particular display.

Stu
_________________________
If you want it to break, buy Sony!

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#216190 - 13/05/2004 21:16 Re: Dead VFD? [Re: maczrool]
tman
carpal tunnel

Registered: 24/12/2001
Posts: 5528
From what I remember when I last had my display board out, it is generated by a SMPS on there. It was some Maxim chip was wired to step up 12V to around 60V.

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#216191 - 13/05/2004 21:34 Re: Dead VFD? [Re: tman]
maczrool
pooh-bah

Registered: 13/01/2002
Posts: 1649
Loc: Louisiana, USA
Well, there's a MAX770 on the board, but it seems to max out at 15 volts according to the datasheet.

(Edit, nevermind. Other voltages are possible as well. It's late!)

Stu
_________________________
If you want it to break, buy Sony!

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#216192 - 17/05/2004 20:54 Re: Dead VFD? [Re: maczrool]
maczrool
pooh-bah

Registered: 13/01/2002
Posts: 1649
Loc: Louisiana, USA
What is there between the output of the MAX770 at the resistor divider and the 60 volt pins at the VFD? Anything? I'm getting 3 volts at the pins and 59.8 volts right at the divider R2. I know there is at least a 22 ohm resistor to one of the pins.

Stu
_________________________
If you want it to break, buy Sony!

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#216193 - 18/05/2004 19:30 Re: Dead VFD? [Re: maczrool]
maczrool
pooh-bah

Registered: 13/01/2002
Posts: 1649
Loc: Louisiana, USA
It was an open 22 ohm resistor that killed the display. Something must have shorted to the common leads on the display and fried it.

We put a temporary through hole resistor across the old surface mount one and now it's working again!

Stu
_________________________
If you want it to break, buy Sony!

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#216194 - 19/05/2004 06:59 Re: Dead VFD? [Re: maczrool]
JBjorgen
carpal tunnel

Registered: 19/01/2002
Posts: 3584
Loc: Columbus, OH
Congrats. Now there's just the memory upgrade empeg to fix.
_________________________
~ John

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