Sharp IS501 OPIC

Tony Duell ard at p850ug1.demon.co.uk
Thu Sep 30 13:13:17 CDT 2010


> 
> At 01:16 PM 9/29/2010, Tony Duell wrote:
> >I havea shaft encoder here in a classic (well, it's over 10 years old 
> >:-)) printer. 
> 
> What make and model of printer?

The printer is an Olivetti JP10 'Sparkjet'.

The encoder unit has the followind moulded int othe plastic cover : 

'Encoder
GP-1R12
Olivetti
Made in Japan'

The encoder is fitted to the front of the print mechanism chassis and has 
as 4 wire cable that plugs into the logic board. To remove the encoder, 
you unclip a cover over the boss of the encocer wheel and remove the 
setscrew that hols this to the carriage cable drum spidle. Then undo the 
2 larger screws on the front of the encoder and slide it off the spidle. 
If the cable drumn comes out of the rear bearing there's a real danger 
the carriage drive cable withl come off and you'll have the 'fun' job of 
sorting it all out.

After rremoving the encoder, it can be dismantled by first peeling off 
the foam insulator on the rear surface. Then desolder the LED wires (The 
LED is pushed into a hole in the front cover) from the PCB. Take out the 
3 screes, nuts and washers. It then separates into 4 parts -- the front 
cover (and the LED, whcih can be pushed out), the encoder disk, the rear 
cover/bearing. and the PCB.

I have done this to mine and refitted the rear cover/bearing to the 
printer chassis just so the carriage cable drum stays in place.

The 4 wires to the logic PCB are +5V, ground and 2 output signals which I 
will bet are the normal quadrature outputs.

The encoder disk is bout 30mm in diameter and has 60 slots in it. 

-tony



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