Diagnosis: Voltages to rank board are fine, checked bulbs.
Fix:
12/2/09 – Swapped bulbs, sockets to test in other rank lights that were working (i.e. Space Captain). Replaced all bad bulbs that were found, verified all sockets were working. Light still not working. Tested caps and transistors, found a bad ceramic cap and one bad transistor. Replaced bad ceramic cap. No change.
12/3/09 – Replaced TIP-110 transistor, Space Cadet light now works.
Symptom: 2 coins always starts 2-player game. Checked diagnostic screen and it showed P2 button always closed.
Diagnosis: Continuity between common ground (orange/red) and P2 button (red/yellow) lines all the way back to the board. Problem on mainboard.
Fix:
10/15/09 – P2 button: Pin 19 on J1 connector. Runs thru R16, R32 which tested good. Traced P2 line back to U3 (a MC14539B multiplexer IC) pin 10, which was stuck high.
10/19/09 – With the help of a friend, realizing pin 10 on U3 is an input, something upstream must be causing the high signal. Tested U3 for shorts (conductivity tests between inputs/Vcc), everything tested fine. A series of pullup resistors and a cap is upstream of that pin…. Pulled resistors, which tested good. Pulled C16 (104Z ceramic axial cap) which tested bad. Waiting for parts.
Diagnosis: Nothing on sound Line 3 (diagnostic screens)
Fix:
9/23/09 – Tons of cold solder joints, pins barely holding in. Resoldered all connector headers on all boards. No change.
9/28/09 – Jiggled 2J3, 10J3 connectors (ROM board to sound board), no change.
10/21/09 – Probed sound board, pin 12 on PIA stuck high. Traced back to the J4 connectors (from ROM to sound bd), all the way back to PIA on ROM board, which supplies the signal. Pin 12 stuck high & never pulsed low when I put sound test into Line 3. 4.7K pullup resistor DIP package tested good. PIA on order from Bob Roberts.
10/24/09 – Replaced PIA on ROM board. Sound lines all present in diagnostic screen & game sounds play fine.
9/21/09 – Replaced 2A fuse, no change. Pulled sound amp board and found tantalum cap at C1 shorted & 2 fried resistors with flame/smoke marks above them. Although the resistors tested in spec, I replaced anyway.
9/26/09 – Replaced C1, sound is back, but garbled and staticky.
10/11/09 – Swapped in a buddy’s working amp board, sounds awesome, so it is the amp board for sure. Replaced TIP31 power transistors on mine, no change.
10/12/09 – Tested voltages, got 16v at all critical locations on board, according to schematic. Replaced CR1/CR2 with a 1N4007, no change. 104Z axial ceramic caps on order.
10/24/09 – Replaced axial ceramic caps on CR1/CR2, and volume pots, no change. Checked R1/R4 again, and realized I replaced with 330 Kohm resistors instead of 330 ohm. Replaced with appropriate value resistors & sound is back. Leaving parts on however, because board sounds better than it did before repair.
Diagnosis: Interconnect cables bad (were previously removed & reseated to test another board)
Fix:
9/23/09 – Replaced 3 connectors with SCSI cables. No change. Found DIP switch thrown which was causing it to stay in test mode. Flipped SW1 open and game booted.
