These instructions regard the Texas Instruments vintage learning aids: Speak & Math, Speak & Spell and Speak & Read.
Modifications & Additions
Replacement: speaker grill foam
Battery compartment: Access Key
Battery removal: Pull-tabs
project box addition
Tools & Materials
Small screwdriver, small scissors, cheap scissors, plastic card, thick plastic tape or ribbon and glue, paper clip, wire clippers.
Step 1: Buying a Used Speak & Spell
Ebay is the main source for finding a speak & spell, other than chance encounters at yard sales and thrift stores. Take precaution in buying one from a new ebayer or anyone with a low rating. The questions to ask are: does it work, have you tested it, is there battery terminal corrosion, is the display clear and what is the cosmetic condition from 1-10. Most auctions will post if it works or not, so ask questions accordingly.
When the package arrives put in some batteries and turn it on. Play all the games and turn it on and off a few times. Make sure to inspect the keypad where children have doodled and scratched, to see if any traces are damaged. If its an original speak and spell, check that no buttons are loose. Leave the batteries inside the unit with the it off for awhile, later on try turning using on, look and listen for anything peculiar. Test out the 1/8 output, if its mono plug it in to a battery powered amp, if its stereo plug in some headphones. Last test is to power the unit with the AC/DC adapter.
After deciding to keep the learning aid, open it up. The screws should be really tight because it hasn't been opened since it was manufactured. Inspect the PCB, use q-tips and rubbing alcohol to clean any build up.
Next use rubbing alcohol to clean the exterior.