Chess Champion from Videomaster
The Chess Champion from Videomaster is a chess computer incorporating a 16-key keypad with information displayed on a four digit LED display. There are six levels, four of which are usable for normal chess.
Technical Details
Mainboard
Component | Location | Datasheet |
---|---|---|
IC 3850PK | U1 | (datasheet) |
IC 3853PC | U2 | |
IC AM9217 | U3 | (datasheet) |
IC AM9111B | U4 | (datasheet) |
IC AM9111B | U5 | |
IC HBF4001AE | U6 | (datasheet) |
IC | U7 | Custom daughter board |
IC SN75492N | U8 | (datasheet) |
Display (ADD 5401) daughter board
- segment F (broken across all digits)
- not connected
- segment D
- segment E
- segment DP
- digit 1
- digit 2
- digit 3
- digit 4
- not connected
- segment A
- segment G
- segment B
- segment C
- not connected
Display Construction
Issues
When powering on random digits or would display random flickering segments or a blank screen, when sliding the S/L switch from S to L the screen sometimes displayed “L” which is the level selection prompt, however this was not always the case, sometimes nothing or garbage.
On opening noticed some rework the traces from corrosion.
First issue broken wires
The main board is connected to the display daughter board by soldered wires, which have broken in a few places, replaced with connectors to allow easy disconnection.
Before | After |
---|---|
Logic Analyzer
Connected Logic analyzer upto the 8 display lines and the input side of the segment driver(SN75492A) to select the 4 segments, by inspecting the output it shows that L is being displayed on the display lines, as digit segments F,D,E are high, when segment 1 is high on the segment driver.