Sharp PC-2500 Users Guide

[rprosperi]

Indeed! Thanks for sharing this robve!

[robve]

(01-29-2021 04:21 PM)rprosperi Wrote:  Indeed! Thanks for sharing this robve!

I decided to take a closer look at the state of the NiCd battery inside the PC-2500 case. What I found was not pretty. The battery had badly corroded at the terminals but also the top of the metal battery holder was badly affected. Fortunately, no contacts or PCB parts were affected by the corrosion or deposits. The deposits were not scattered throughout the case yet, but that could have easily happened when the unit was shipped. Others may not be so lucky.

Before the battery can be reached and removed, a gray ribbon cable should be disconnected by sliding the black tab and pulling the ribbon out. To put this cable fully back in place takes a bit of effort. But that's really all it takes besides removing six screws from the bottom then lifting the housing at the back while loosening two tabs located on each side of the unit (the printer side tab comes easily loose). Make sure to stay grounded to avoid ESD.




The battery holder sits right below two ICs located on the main PCB below the keyboard. There is only some thin plastic tape glued to the metal holder of the battery pack to protect the exposed ICs above it. In my case the the metal battery holder was corroded just underneath its plastic tape as you can see.

I removed the battery and cleaned the case. The JST connector with the red wire (+) and black wire (neutral or -) pictured below gave me a lot of trouble to disconnect. I could have cut the wires but want to reuse the lead with the connector to install a new battery pack.




I verified that the unit works fine without battery when plugged into power.

I ordered new NiCd AA batteries with tabs to solder. I will reuse the old JST connector with lead to install the new battery pack.

PS. The batteries with solder tabs (5-pack Exell NiCd AA on Amazon) work great. Luckily I ordered a type that has no tops so these fit the battery tray on the bottom of the device (requiring the batteries to fit tightly against each other). I managed to clean the leads of the JST connector to solder, which had oxidized. Otherwise order a new JST PH 2 female connector with 20mm lead.

- Rob

[robve]

The PC-2500 works very well, despite its age. Very glad with this acquisition. I have plotter pens and paper. The manual explains the printer commands in BASIC, but leaves some details out that got me into trouble because I am used to the PC-1500 commands.

To keep my sanity I put together a cheat sheet for printing with the PC-2500:
  plotting.txt (Size: 2.72 KB / Downloads: 3)

Three cool BASIC programs:

  flower.txt (Size: 1.12 KB / Downloads: 3) flower drawing demo program originally for the PC-1500, short but sweet!

  globe.txt (Size: 6.8 KB / Downloads: 2) a globe drawing program initially for the PC-1500, very cool!

  alcatraz.txt (Size: 7.06 KB / Downloads: 2) an auto-learning game I wrote, gets smarter the more you play (uses AI, no plotting)

  alcatraz-manual.txt (Size: 1.95 KB / Downloads: 2) instructions to play alcatraz

Load with CLOAD from a PC with bas2img --pc=2500 file.txt and bin2wav --pc=2500 file.img, see Pocket Tools for SHARP Pocket Computers.

- Rob