Category Archives: Gottlieb

Arcade Tech and Repair, Gottlieb, Repair Logs, Uncategorized

Odd Display Issue in Gottlieb Haunted House pin

So I was helping a friend with his Haunted House (HH) pin. The bottom playfield stopped kicking the ball back onto the main playfield, and the two right score displays and the center credit/ball display would distort on a cyclic basis – they would show all segments in a flash-flash-pause, flash-flash-pause pattern, and this happened when the game was in attract mode, test mode, or being played. 

The playfield problem was from the three connectors for the bottom playfield not being routed correctly and he accidentally unplugged them when lifting the main playfield – two of the three of them were disconnected. We routed them through the little slot at the back of the bottom playfield, connected everything up and it all started working again. Continue reading Odd Display Issue in Gottlieb Haunted House pin →

Arcade Tech and Repair, Gottlieb

Theory of Operation of the Shaq 27722-1 (A23) LED Display Board

Theory of Operation of the Shaq 27722-1 (A23) LED Display Board (4-player score board).Theory of  Operation of the Shaq 27722-1 (A23) LED Display Board (4-player score board).

Theory of Operation

This is a brief technical introduction to the operation of the 27722-1 (A23) board.  It will cover inputs and behavior of the board.

Inputs

This board accepts the following three control inputs:

  1. Master Reset (/MR)
  2. 8-Bit Data (DX0–DX7 – pulled up to +5v/VCC)
  3. Enable/Strobe for the latches (AX4)

It also accepts +5, common GND, +12 and the +12V GND (both GNDs are connected together). 

The incoming 8-bit data is split into two 4-bit words with the low word (DX0–DX3) used for specifying the value to display on a particular LED digit via the ‘4511 (BCD to 7-segment latch/decoder/driver), with DX0, DX1, DX2 and DX3 connected to inputs A, B, C and D (or D1, D2, D3, and D4), respectively.  The high word (DX4–DX7) is used for digit selection via the ‘4514 (4 to 16-Line Latch/Decoder/Demultiplexer), with DX4, DX5, DX6 and DX7 connected to inputs A, B, C and D, respectively.  

Latches for the corresponding chips are controlled via the AX4 signal, which is directly connected to the 4511’s /LE input and also goes through an inverter whose output is connected to the 4514’s LE.  

The /MR signal is connected to the 4511’s /BI signal, which is used to blank the displays whenever the game is in reset.

Continue reading Theory of Operation of the Shaq 27722-1 (A23) LED Display Board →