LED display available

[PANAMATIK]

(06-25-2015 11:08 AM)Didier Lachieze Wrote:  

(06-25-2015 09:33 AM)BartDB Wrote:  Some Commodore calculators have the same displays as your picture of "old display". They are not sealed so the electrolyte of leaking batteries corrodes the bonding wires, and as you say there is no hope .

I have a Commodore SR-4190R with this issue and I'm wondering what it would take to replace the bad display with a new one using the Sparcfun LED modules:

There must be met some requirements for replacing a display.

It must be a common cathode LED display, because the QDSP6064 has connected the cathodes of all segment diodes of each digit to one pin. It must be a multiple of four digits, because the QDSP6064 is a 4-digit module. Your SR-4190R display has 14 digits, which does not meet this requirement. Perhaps you can use 16 digits and don't use one on either side if there is enough space. In any case you must produce a wiring layout identical to your display pins. And the new height of the display must find space in the calculator. Sometimes there is no single mm left. In the HP-25 it fits perfectly, but the new digits are closer to the screen than the original. The voltages should be no problem, because all red LED modules uses the same forward currents at that time.

The HP-2x etc. LED displays are not sealed either. I have a totally corroded HP-19C module looking like yours. But I think I can replace that. Unfortunately all the other components are corroded the same and I still haven't started any repair.

Bernhard