Astrocade

Chip Info

Main PCB

• VR1: +12V Regulator: LM342-P-12 (Listed in manual as +15V LM342-P-15, but there is probably as +12V Regulator installed)
• VR2: +10V Regulator: LM342-P-10
• VR3: +5V Regulator: UA78GU1C and TIP31
• VR4: -5V Regulator: LM320 MP or 7905C

• U1: ROM: 9316B HVSA
• U2: ROM: 9316B HVSB
• U3: ROM: 9316B HVSC
• U4: ROM: 9316B HVSD
• U5: 74LS367
• U6: 74LS04
• U7: CPU: Z80
• U8: 74LS257
• U9: 74LS257
• U10: DP8304
• U11: 74LS02
• U12: 74LS00
• U13: 74LS10
• U14: 74LS10
• U15: 74LS02
• U16: 74LS74
• U17: Address IC: 0066-115XX-XXYX
• U18: Data IC: 0066-116XX-XXYX
• U19: IO IC: 0066-117XX-XXYX
• U20: 74LS174
• U21: 74LS74
• U22: 74LS74
• U23: DM81LS95
• U24 - U31: RAM 4096 or 4027
• U32: 75361AP

Other Logic:

• 7416

RF Modulator

Astec UM-1291-1

Quick Voltage Reference

The Astrocade uses 4 different voltages with no clear test points for taking measurements. The pictures below show a few places to take measurements and the locations of the regulators.

• 

  AC input voltage, test points at rectifier diodes.

• 

  +5, +10 points on U17 and U19

• 

  -5, +5, +12 points on RAMs U24-U31

Schematics

• 

  Full sheet schematic

• 

  UM1291-1 Modulator

Service Manual

• 

  Bally Arcade Service Manual

Overheating Chips

Heat is a notorious killer of Astrocade consoles due to air circulation problems.

An Astrocade should never be left on a carpeted surface, or in any location where heat cannot convect through and away from the console.

Inside, a large bank of chips is covered by RF shielding. Many Astrocade owners opt to improve airflow by removing this shielding. In a peculiar design choice, attached to that shielding is a "heat sink" for one of the 40-pin DIP chips. I put heat sink in quotes because it's really just a bar of metal with no cooling fins. (We have upgraded heat sinks that are more effective)

If the shielding is removed, a proper heatsink and thermal compound should be used on that chip. Even if you don't remove that shielding, a proper heatsink wouldn't hurt.

Capacitor List

Purchase these parts as a kit (see revision below)

A080-90701-B620

A080-90701-B620
	
C1	1500uF	25V
C6	10000uF	10V
C7	15uF	25v
C8	15uF	25v
C10	100uF	16V
C13	1uf	50v
C62	15uF	25v
C63	15uF	25v
C64	15uF	25v

NOTE: For our cap kits we substitute 22uF in place of the 15uF.

Failed Astrocade tantalum cap (Photo courtesy Scott at Stardust Arcade)

Note that the 15uF parts may be black tantalum capacitors. Later revisions of the Astrocade feature electrolytic capacitors. You might consider replacing the tantalum caps with electrolytic as tantalum caps are also prone to failure.