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.
http://www.hpmuseum.net/exhibit.php?hwdoc=122


-Rik




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