[personal] Shaft encoder in HP2631B printer

[Rik Bos]

> -----Oorspronkelijk bericht-----
> Van: cctalk-bounces at classiccmp.org 
> [mailto:cctalk-bounces at classiccmp.org] Namens Tony Duell
> Verzonden: maandag 25 januari 2010 20:27
> Aan: cctalk at classiccmp.org
> Onderwerp: Re: [personal] Shaft encoder in HP2631B printer
> 
> > Sounds like it may be a HEDS or HEDL encoder as it's HP, 
> any chance of 
> > a photo or a p#.
> 
> 
> 
> It has a number QEDS8997 on the end cover (the part that 
> carries the LEDs). There  may be a number on the other end of 
> the housing, but I can't remove it to check, the screws 
> holding it to the bearing plate are covered by the encoder 
> disk that's emoxied to the eladscrew and which needs the 
> special tools (according to HP) to remove/replace.
> 
> I cna't easily provide a photo (no digital camera). If you've 
> ever worked on HP9000/200 machines, it's similar to the 
> encoder used on the twiddleknob on the keyboards of said 
> machiens, but without he spindle/mounting bush. 
> 
> > > Anyway. Iv'e read the HP service manual (on 
> http://www.hpmuseum.net) 
> > > and
> > 
> > Link to the manual ?
> 
> The easiest way to get to it is to go to said site, then 
> naviage through 'printers' 'impact' 'hp2531' 'product 
> documentation'. You'll then see a serevice manaul (and a CE 
> manual) for the 2630B series listed. I think the encoder i 
> nthe 2531A is similar, the one in the 2631G is very different 
> (and, alas, looks a lot more repairable from the manual).
> 
> 
> > We use HEDS an HEDL's all the time, no special tools.
> 
> According to the manual, this encoder was supplied as 3 
> separate parts. 
> The housing, constianing the sensorts and with the cable 
> fixed to it ; the encoder disk; and the end conver containing 
> the LEDs.
> 
> THey are fitted in that order, and removed in the reverse order.
> 
> The hub of the encoder disk doesn't have a setscrew or 
> similar. It is glued to the hend of the leadscrew with epoxy. 
> One tool is used to remove the disk (it hocks round the hub, 
> and a screw then applies pressure to the ned of the shaft to 
> pull the disk off, breaking the epoxy bond. The other tool is 
> used to bet the disk back on the spindile, it, again, fits 
> round the hub and rests against the end of the housing, this 
> getting the disk the right distance inside.
> 
> What is not clear ffom the manual is wheter this procedure 
> damages the disk, or whether you can refit the old one if you want to.
> 
> My guessis that he other reply is correct, and that the LEDs 
> are out. If that's the case, I may not need to remocve the 
> encoder assembly. The end cover carrying the LEDs comes off 
> anyway. The whould thing can be removed from the printer 
> complete with leadscrew, bearing, and bearing cover plate. 
> And after doing that it's possible to unclip the cover over 
> the cable and get to the edge of the snensoor PCB. Maybe that 
> will be enough.
> 
> -tony

The HP 9000/200 series knob encoder uses a small bulb, witch I replaced for
a white LED (3mm type).
I had to remodel the LED a bit to make it fit.

-Rik