- 1 Chips and ICs
- 2 Vectrex Service Manuals
- 3 Troubleshooting Chart (Subset from GCE Guide plus additional tips)
- 4 Yoke Magnets
- 5 Schematics
- 6 Capacitor Lists
- 7 Capacitor Replacement - Pulled Via Warning
- 8 Relocating Power Board Capacitors
- 9 De-Buzzing the Audio
Chips and ICs
- IC201: ROM: 2363
- IC202: Line decoder: 74LS00
- IC203: Line decoder: 74LS32
- IC204: RAM: 2114
- IC205: RAM: 2114
- IC206: CPU: 68A09
- IC207: PIA: 6522
- IC208: Sound: AY-3-8912
- IC301: DAC: MC1408P8
- IC302: Multiplexer: 4052B
- IC303: X/Y/Z sample & hold: LF347 / TL084 / MC34004P
- IC304: DAC current to voltage conversion / joystick voltage comparator: LF353 / TL082 / MC34002P
- IC305: Analog switch: 4066B
- IC101: +5V Regulator: LM340
- IC102: -5V Regulator: 7905
- IC103: Audio amp: LM386-3
- IC401: Deflection amp: LM379
- IC501: Flyback driver: LM555
Vectrex Service Manuals
Troubleshooting Chart (Subset from GCE Guide plus additional tips)
- Unit will not power up
- Measure resistance at A/C plug. Should read 10 to 21 ohm +/- 5%
- T101 primary winding open or shorted
- Check fuse F101
- F101 open
- Check SW301 - turn unit on and make a continuity check of the A/C switch
- SW301 open or shorted
- No Vector / Intermittent cector / Intensity bad
- Select Test #3 on diagnostic cartridge
- Check for +/- 5 VDC and -13 VDC at connector J204. Left to right: -5, GND, +5, -13
- D101 - D104
- IC 101, 102
- Measure AC input voltage to power supply PCB
- EP105 (center tap) to EP106 = 8.6 VAC
- EP105 (center tap) to EP104 = 8.6 VAC
- CAUTION: When replacing Power Supply wires, insure you check continuity on both sides of Power PCB
- Check that there are no shorts between the +9 and -9 power supply to GND: T503 (IN) - T401 (IN)
- Remove T401 or T503 and check that there are no shorts to GND.
- Check for short between heat sink (on Power Board) and IC401 heat sink.
The adjustment magnets aren't very obvious if you don't know exactly what you're looking for.
Stitched together from the service manual:
Pay no attention to the parts list in the service manual. It is incorrect in several different places. The schematics are slightly less inaccurate, but still don't represent the final product.
Power Board: C109 4700uF 25v C113 10uF 16v C114 220uF 16v C117 10000uF 25v C118 10000uF 25v C119 4700uF 25v C120 47uF 16v C121 47uF 25v C122 220uF 25v C404 1000uF 25v C409 .47uF 50v (BP) C410 .47uF 50v C411 1000uF 25v C504 47uF 16v C507 47uF 100v C508 47uF 100v C511 22uF 16v C512 22uF 16v C513 1000uF 25v C516 3.3uF 350v C521 47uF 16v C523 470uF 16v CPU Board: C211 220uF 16v C212 100uF 16v C213 100uF 16v C323 4.7uF 16v
Provided due to sometimes inaccurate listing in the service manual, and as reference for the Integrator Cap Kit. These caps are non-polarized.
C304 .0047uF 50v C305 .01uF 50v C306 .01uF 50v C312 .01uF 50v C313 .01uF 50v
C304 .0047uF 50v C305 .0047uF 50v C306 .0047uF 50v C312 .01uF 50v C313 .01uF 50v
Revision 3GE - MB low-buzz model, not styrene caps but provided as reference
C304 .0022uF 100v C305 .0022uF 100v C306 .0022uF 100v C307 .01uF 100v C312 .01uF 100v C313 .01uF 100v
Capacitor Replacement - Pulled Via Warning
It's very easy to pull the vias out of the Vectrex PCBs during service. I've seen examples where several of the large filter caps on the power board have traces on both the top and bottom of the board that connect at a cap but don't have a plated via. For example, power might come in to the cap on the bottom of the board, be soldered to the cap leg, and continue on to the rest of the circuit on the opposite side of the PCB. I've made it a habit to check for missing vias, leave a small gap between large caps and the board, and apply solder to both the top AND bottom of the PCB.
Relocating Power Board Capacitors
There are 2 caps located under the big heat sink on the power board, C409 and C410. When I recap a Vectrex, I relocate them to the back (solder side) of the board. This way they can be serviced without removing the entire heatsink assembly.
De-Buzzing the Audio
If you've never heard a Vectrex, then you may not be aware of how much of the hum from the monitor circuits is picked up by the audio circuit. The volume setting has no control over the amount of buzz, whether it's at no volume or full volume, the amount of buzz remains the same.
Over the years, a few remedies have cropped up:
Method #1: Cover the speaker grille with packing tape
Not very elegant, but actually works fairly well. This provides a mechanical means of reducing the total speaker output, both buzz and game sounds included.
Side note: If you have kids that have really loud and annoying electronic toys, tape over the speaker grille is a great first step in reclaiming your sanity.
Method #2: Grounding modifications and shielded audio cable
This reduces the amount of buzz to a more tolerable level. A free mod, provided that you have some scrap coax cable hanging about.
Method #3: Audio pre-amp circuit
This modification, originally drawn up by Bill Seiler, gives a very noticeable reduction in the amount of hum. The idea is that the audio output from the logic board is increased, and the final amplifier gain is decreased, thereby lowering the noise floor of the system.