Vectrex Repair (Black Screen / No Vector)

I’ve wanted a Vectrex Console for quite a while, and finally acquired a broken Vectrex for a reasonable price on eBay (where else) with the idea of repairing it…

It didn’t begin well when the courier who delivered the package left it hidden behind a car… overnight… in the rain:

hermes1

It was sitting in a puddle, and got a fairly good soaking. Here’s the Vectrex emerging from the box:

hermes3

Fortunately, after drying it out carefully, it didn’t look like it had sustained any serious damage, so I set about trying to repair the fault.

Exactly as described by the seller, when it was powered on, the game sounds were playing, but the screen was completely black, not even a white dot visible on maximum brightness.

Looking at the troubleshooting guide, the first suggestion for “No Vector” is to “check for +/-5 VDC and -13 VDC at connector J204. Left to Right -5, GND, +5, -13”. When I checked J204 on the Logic Board, the -13V DC rail was missing (just measured about 0.67V which looks like a diode voltage drop). I checked the other end of the -13V wire on P204 on the Power Board, with the same result. This confirmed the wires and connectors were OK, and it was a problem on the Power Board.

From the service manual, here’s a diagram of the -13V power supply circuit on the Power Board:

vectrex-13v-repair1

The two lines at bottom right are the incoming power supply which is about 9~10V AC. The Diodes D106 & D107 and the Capacitors form a voltage doubler, boosting this to 18~20V, which is then regulated by a 13V Zener DZ102.

I switched off power and tested D106 and D107 in circuit with a DMM, and it looked as though D107 was short-circuit. The resistor R106 looked fine. Since there were only a few components, and the 34 year old (!) Electrolytic capacitors were probably not in the best shape, I decided to replace the whole -13V regulator circuit.

The -13V rail is only used by IC301 (the MC-1408P8 DAC) and the circuit diagram even states “TO IC301 PIN3 ONLY” next to the -13V line so, after a quick visual check of the Logic Board and connectors, I couldn’t see any obvious signs of a short on the -13V rail which might cause it to fail again. It’s always worth checking before replacing parts though!

To do this repair, the whole Power Board needs to be removed, which involves removing 5 connectors, removing the HV lead (CAUTION: ensure it is discharged first) and desoldering 2 ground leads, 3 power leads and 4 leads connecting the CRT deflection yoke. The board is secured with two small cross-head self tapping screws.

Here’s a close up of the components to be replaced (C120, C121, C122, D106, D107 and DZ102):

vectrex-13v-repair2

This picture highlights them more clearly:

vectrex-13v-repair3

After removing the components, the most difficult part of the repair was clearing solder from some of the holes connected to the ground plane…

Once the original components were removed, I was able to test them out of circuit and found the following:

  • D106 was OK
  • D107 had failed Short Circuit
  • DZ102 was OK and measured 13.2V
  • C120 measured 44.1uF, 2.1Ω ESR, Vloss 4%
  • C121 measured 49.9uF, 0.65Ω ESR, Vloss 3%
  • C122 measured 234uF, 0.13Ω ESR, Vloss 1.3%

Presumably with D107 short circuit, this may have also damaged C120 by putting AC directly across the polarised electrolytic. In any case, I decided to replace them all with new parts.

For the Zener diode, I used a 1N5243BTR (0.5W, 13V. DO-204AH). The diodes D106 and D107 were replaced with 1N4148 as used originally, and C120, C121, C122 replaced with equivalents.

After refitting all the connectors and soldering all the cables back in place, I left the connector at J204 disconnected from the Logic Board and tried measuring the -13V rail with the DMM probes touching the connector contacts. Initially, it wasn’t looking good as the -5V and +5V rails were present, but -13V wasn’t…. anyway, I decided to plug it into J204 and power on again…. and happily the Vectrex sprung back into life again! Perhaps the DMM probes were just not making a good contact with the connector?

Here’s the first power up after the repair:

For a machine that’s over 30 years old, I was astonished how beautiful and sharp the vectors looked – the display is amazing! (the video above does not do it justice). I’m very excited to finally have a Vectrex to tinker with… now I just need some more games and overlays!

The console has the famous “Vectrex buzz” from the speakers, and I think the next project will be to try and fix that…

23 thoughts on “Vectrex Repair (Black Screen / No Vector)”

  1. Thanks a lot great details
    I too have the exact same problem and have pulled apart the whole console and cleaned and re soldered things and nothing . I found I wasn’t getting 13 v most people are lucky and just clean the pins but nope . So I need to do this repair – when testing all three caps there c102 – the all have 0.62 0.22 readings and when testing others on the board they read 13

  2. Hi Matthew

    No problem, pleased you found it useful. I’ve also heard that many people find it is just dirty contacts, but in my case it was D107 that had gone short-circuit.

    It would be worth measuring the resistance of D106 and D107 to see if they are shorted or open circuit. With power disconnected and a resistance meter across each diode, it should only conduct in one direction. In my case, D107 conducted in both directions, showing it had failed short-circuit.

    I replaced all 6 components (D106, D107, DZ102, C120, C121, C122) although only 2 components were actually damaged (D107, C120) in my Vectrex.

    I hope you are able to get it working again. Let me know if there’s anything I can do to help.

    1. James are you in Southern California by any chance and if so what would you charge to fix my vectrex with the same issue?

      1. Hi Kyle
        I’m in the UK so not really feasible unfortunately – but if there’s anything I can do to help remotely (e.g. with a DIY repair) let me know.
        Best regards
        James

  3. Well actually it’s late at night
    What could I use for equivalent caps ?
    I took out the 120 and it seems I had the exact same one but the others have
    25v 47 uf
    Looking around I find some at 25v and 100uf
    Is that too much ?

    1. These capacitors are there to smooth the supply, so I think you should be able to safely use a larger value capacitor (but not a smaller value). As far as I can see, substituting the existing 25V 47uF capacitors with 25V 100uF should be OK. Similarly, a capacitor with higher voltage rating should be OK. The most important things are that the voltage should be 25V or above and it is critical to get the polarity right.

  4. It’s the diodes they read .64 .2 off that 13v so I’ll look into changing those I changed the 122 the last one I think and the other two I found larger ones
    Still powers up and the same thing but yeah for me I think it’s the diodes
    What should they read ? I saw d102 you had 12v

    1. When you say .64 and .2, do you mean the voltage measured across the diodes? If so, then 0.64 sounds reasonable but 0.2 sounds like the diode may have failed.

      Another way to check is to disconnect the power completely, then put the meter on the resistance range, and test D106 and D107 by trying the meter probes in both directions. You should find that the diode gives good continuity (low resistance) in one direction through the diode (with black meter lead at the cathode – i.e. the end of the diode with a stripe) and is open circuit (high resistance, infinite) with the red meter lead at the cathode. However, if it shows no (0) resistance in either direction, then the diode has failed short-circuit. Similarly, if it shows high resistance in both directions, then the diode has failed open-circuit (much less likely).

  5. $8 in parts I jut brought all new ones
    Thanks for you guide I was asking the guys which ones I need and s rolled up to your perfect diagram with the ratings on there thanks it saves a lot of head bending inside to look lol

    Up date tonight in repair and if I have to send you beer lol

  6. I also may have made a mess
    I had to put the diodes sitting up high not poking through I was heating up too long I was worried and one point under neath lifted off
    Also put two caps on the back too as they also wouldn’t poke through
    They all sit in and all read the same no 13v anywhere

  7. Hi

    I have 2 Vectrex machines that were perfectly working until they were mistakenly stored for 2 years in the garden shed.

    Now, there is no, or a badly distorted image, but the sound and built in game seems to work fine.

    Would you be able to fix these for me for a service / repair fee?

    Please let me know.

    1. Hi there, excuse the delay in reply I’m just back from the USA. Well, I’m massively busy with work, but if you’re not in any rush and can wait a while, the idea of trying to bring some dead Vectrii back to life does appeal to me! So yes, I would definitely consider it if you cover cost of parts etc. and accept it would be on best endeavours (i.e. no guarantee I can fix it, but willing to give it a shot).

      1. Hi there, strangely similar question here…

        This is going to sound like a weird wait-for-ages-then-4-come-along-at-once sort of situation but I also have two broken vectrexes that have also suffered from an unscheduled stint in a garden shed! A lot longer than 2 years for mine though, it could have been several more before I realised my dear old mum’s terrible error and rescued them.

        I don’t recall either one being broken when they were stored but neither box did anything at power up when I last tried. Whacking brightness to max showed the white dot tho so the tubes are getting power and might be ok.

        I don’t suppose you fancy a go at mine too? One of them is terribly dear to me (an early GCE model imported by my dad in the early 80s so probably one of the first in the country) but the other was just a standard UK MB one I bought from a tv rental shop for the games when nobody wanted to rent it anymore. I’d be more than happy to part with the latter as a thankyou for getting the former working if that helps motivate ☺

        Anyway, let me know if you’re interested in helping to save a wee bit of console history!

        Steve

        1. Oh wow, this is escalating ha ha!
          I’m insanely busy with work & family commitments, so really I should say no rather than getting into the Vectrex repair business, but I guess nobody repairs these things nowadays and would like to help if I can. I’ll drop you an e-mail in a few days to discuss.

          1. That’s OK, I understand ☺

            I do actually have some limited electronics experience but am wary of the CRT voltages. Maybe some initial guidance from yourself might give me the confidence to attempt some basic troubleshooting myself? Look forward to your mail in any case ☺

            Ta!

        2. Steve, if you’re still looking for help perhaps I could be of assistance. Is there a way to get in contact with you via email, google hangouts, FB?

          1. Hi Sam
            Steve and I continued this conversation offline by e-mail, and he actually managed to get his Vectrex working again by replacing some of the 6522s which he salvaged from an old VIC20 🙂
            We forgot to update the blog here for the benefit of our other dear readers!
            Kind regards
            James

  8. Can anyone in the UK help me my beloved vectrex was working fine halfway through minefield the screen went blank sound and power seem OK but no picture. No dot. I’ve cleaned connection but no joy. Screen does flicker when you turn it off and flashed white when powerd down could this be a capasitor if so what one?

    1. Hi Mike
      There are a number of possible causes for “no vector”, but it sounds like a similar fault. The “Vectrex Troubleshooting Guide” Page 12 suggests checking for presence of the +5V, -5V and -13V supply voltages at J204 (Left to Right: -5, GND, +5, -13).
      Have you got any electronics experience & what’s your comfort level for attempting a DIY repair?
      Regards
      James

  9. Thanks a lot for this post James
    I had audio but just black screen on my Vectrex when I tried to start it after a few years of no playing. I found your post with Google, confirmed the issue with -13v missing, changed the six components and my Vectrex was almost like new again. Success!

    1. Hi Roland
      That’s great news! Glad you got it working again! I’m also planning to spend some time playing my Vectrex over the Christmas holidays!
      James

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