1736 - Sharp ELSI-804 calculator

Documents: Schematic / BOM

     This kit includes the PWB and all the parts in the BOM not pulled from a working ELSI-804 calculator as well as a cable and connector to connect to the original power transformer.

     This PWB takes the parts directly from an original Sharp ELSI-804 (EL-804) 9 digit calculator (8 Digits plus sign/error) from the '70s and adds an integrated keyboard for a pleasant open-face design.  The result is a 5.5 x 4.0" retro VFD calculator that can be easily probed and studied.

     All the semiconductors are used as well as the four 10-pin resistor networks and, of course, the 9 fluorescent display tubes (With the original foot prints).  The discrete R's and C's are replaced with 1206 chip parts, except for the two 18 ohm filament resistors that are 2W 2512 chips and the electrolytic capacitors which are modern versions of the originals.  A 1206 SMT poly-fuse replaces the 250mA glass fuse that was mounted to the original PWB.

     The TO-220 power transistor was originally mounted to a heat sink but is now mounted to the PWB on a large copper radiator which keeps the temperature rise to a minimal 6C.

     The transformer that used to be mounted to the original single sided phenolic PWB is now connected via a 6 pin cable (Included with this kit).