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Chips and ICs

CPU Board

Power Board

  • 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 Vector / 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.

Yoke Magnets

The adjustment magnets aren't very obvious if you don't know exactly what you're looking for.


Stitched together from the service manual:

Capacitor Lists

Electrolytic Capacitors

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.

Purchase these parts as a kit

Power PCB Cap Map
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

Polystyrene Capacitors

Provided due to sometimes inaccurate listing in the service manual, and as reference for the Integrator Cap Kit. These caps are non-polarized.

Revision 2GE

2GE Label
C304 	.0047uF	50v
C305 	.01uF	50v
C306	.01uF	50v
C312	.01uF	50v
C313	.01uF	50v

Revision 3GE

3GE Label
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 Plated Through Hole Warning

It's very easy to pull the plated through holes (PTH) 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 PTH. 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 PTHs, 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

Original locations for C409 and C410
Relocated C409 and C410

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:

Waveform showing reduction in amount of audio buzzing after performing the pre-amp modification, recorded with a digital camera microphone at 4" from speaker. Leftmost waveform is an unmodified Vectrex. The middle waveform represents Method #2, and the rightmost waveform is after performing Methods #2 and #3

Listen to sample audio of before & after modifications

The average peak values are approximately -15 stock, -22 method #1, -30 method #2, for a noise reduction of 7db and 8db respectively.

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.

HOWTO Guide: Vectrex Shielded Wire Buzz Reduction

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.

HOWTO Guide: Vectrex PreAmp Buzz Reduction