HP Integral / display schematic ?

Rik Bos hp-fix at xs4all.nl
Wed Dec 30 08:16:04 CST 2009


> -----Oorspronkelijk bericht-----
> Van: cctalk-bounces at classiccmp.org 
> [mailto:cctalk-bounces at classiccmp.org] Namens Jos Dreesen
> Verzonden: woensdag 30 december 2009 14:18
> Aan: General Discussion: On-Topic and Off-Topic Posts
> Onderwerp: Re: HP Integral / display schematic ?
> > I assume you mean that the power rails were fine, and there were 
> > sensible waveforms on the other pins.
> >   
> Indeed, voltages ok and syncsignals as described in the HP 
> Journal article.
> >   
> >> The small PCB mounted on the back generates a blanking signal that 
> >> was also correct.
> >>     
> >
> > Right. It's neen a long time since I've looked at one of these 
> > displays. Is this a little PCB on top of the display PCB itself?
> >   
> No, it is a small PCB mounted on the plastic frame,  and it 
> contains 5 TTL to calculate the framing signal from H and V 
> sync. Should have been done in the displaycontroller imho.
> >> This was indeed the culprit : it is a 5V to 5V isolation 
> converter, 
> >> used to power some logic that is required on the far end of high 
> >> voltage
> >>     
> >
> > Where does it get the HV from? It must be generated on the 
> display board itself.
> >   
> The very small pcb mounted on top of the displaycontroller 
> board is the 5V convertor.
> The high volatge is probably generated with the small 
> transformer on the big board.
> >> I would still be interested in any schematic of the driver 
> >> electronics of any Epson electroluminiscent display
> Of course is is actually a Sharp display...
> Still would like to know why it needs a CPU & Eprom, since it 
> has already all required signals.
>           Jos

Mine is working fine until now..
When I got mine it wasn't used for several years, and I got the Idea it
wasn't used much in the years before. And I did checked the screen signals
and had the idea it was the HV-supply not having a high enough voltage to
ignite the screen cells.
Or one of the little japanese who live in old electronics wasn't awake yet
Never the less after letting it (by accident) on for a few hours the screen
switched on. And it stays working..
Did you read the HP journal article about the Integral ?
It describes the engineering background of the Integral.


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