Vectrex repair Project

[r0jaws]

Just in case I get bored I'm starting up yet another project.
This time it is just to repair an ailing Vectrex.
I'm sure you may be familiar with this unusual piece of kit but in case you're not, It's a gaming system first released back in 1982 (Wikipedia). There is still quite a following, but personally I had not bumped into one until Byte Back this year. I was smitten. :inlove:
The novelty of a pure Vector graphics home arcade is just something that can't be emulated satisfactorily as far as I'm concerned.
This one I bought recently is desperately in need of some TLC, and that's what she will get.

Basically she two problems,
1. She has a sound fault, ie No sound/ very intermittent sound.
2. A couple of display faults.
a. There is a bright spot in the centre and all the points for the vector graphics have lines converging on this central point making a sort of spider web.
Now, usually, this is syptomatic of the brightness being too high, but the brightness setting is basically On/ Off at the moment.
b. Any Text displayed appears as Bars.



A bit of research on Black and White Vector monitors leads me to believe that there are a few things that need to be checked and replaced.
I imagine nearly all the capacitors are pretty duff and will need checking and replacing. The soldering looks pretty rough, I think it may need reflowing in some cases.
According to the manuals, some of the display distortions can be caused by a dodgy PSU, so this will have to be checked.
The brightness and contrast Pots may need checking and the capacitors in the spot killer circuit (if it has one) need to be checked.

Anyhoo, Here's some picture of the filthy little minx with her back off.

The offending brightness knob.

Oh Dear Oh Dear, this doesn't look very nice at all.

Finally, a picture of the Logic board I tracked down on t'interweb.

I've also got a PDF of the original service manual complete with full schematics and parts list.
This should be a great deal of fun, just so long as I don't blow myself to pieces discharging the CRT!
I'll keep you all updated anyway.

 

[Merlin]

Re: Vectrex repair Project

Phil,

Have you tried reseating the chips on the lower board?

I noticed that IC208 controls the sound and is a socketed chip. Maybe a lift and reseat of the chip may restore the sound fully, as I imagine that these machines would have run quite hot, so 'creep' of the chips due to heating up and cooling down could be an issue.

 

[r0jaws]

Re: Vectrex repair Project

So far I have just taken the back off and pressed firmly down on all the socketed chips, but I think a re-seat may prove fruitful.
I'm just being cautious and doing a bit of research first, especially around the back of the tube!

 

[Merlin]

Re: Vectrex repair Project

That sounds like a good plan to me; some of those larger capacitors can pack quite a whack if they haven't discharged. Some of the tube voltages can be a bit scary, too..... :shock:

 

[Kin Hell]

Re: Vectrex repair Project

@ r0jaws

Try & get all that dust out b4 you pull any removable boards & avoid getting that dust wet with cleaning solvents or you'll have a 'cement' nightmare ahead of you. :nod:

Hell of a project m8y & I really hope you are successful.

Kin

 

[User1301]

Re: Vectrex repair Project

That's a shame about the sound Phil. Every time I turned it on the sound seemed ok - a bit scratchy with the volume control but that's normal for old analogue kit I think. Happens with radio's a lot. I think the chip reseat might be a good idea as it went a long way in a truck to get to you. Please, please be careful in discharging the CRT - would hate for anything to happen to you because of something I sold you!

The project looks like it will take some time and I'll watch with interest now that I have subscribed to your thread!

Good luck mate

John

 

[r0jaws]

Ok, this has been an ongoing project on my backburner and I thought it was time to have an update.
I managed to get hold of a second ailing Vectrex which had a knackered logic board but working screen.

My logic then follows that I swap boards and, POW! one working Vectrex and one for spares. At least, that was the plan.

Now, I have to admit to a little trepidation in messing around inside what is essentially a CRT but with care it isn't really much of a problem.

Firstly I removed the back of the Donor vectrex and unplugged the 2 power connectors.

After removing the Power knob on the front it was a case of removing 4 retaining screws and unplugging the video and audio cables which connect the Logic Board to the Power board. These are pretty tricky to access, being close to the front, but they do pop off fairly easily once you get hold of them.
The whole logic board and PSU assembly is mounted on a sub frame which once unscrewed easily slides out. The PSU feeds the power board with three red and white wires, which I cut with snips.

This is the unservicable logic board/ PSU assembly fully removed.

This is the donor Vectrex, known good Video unit and Power Board.

It was a simple matter then to repeat the process with my original Vectrex, removing it's working Logic board and inserting it into the donor case.

I am ashamed to say that in my anticipation in getting the job done I let myself down with some rather shoddy soldering.
I was finding the grounds particularly difficult to remove and managed to get a pretty "dirty weld" which I didn't continuity test. My multi-meter was on the fritz at the time, in retrospect I should have just waited but sometimes I just get a bit excited.

Not surprisingly, on completing the reassembly, powering up resulted in nothing, nada, ziltch. Bother. oh:

I decided to take a bit of time out to assess my failure and speak with wiser heads, whilst also having a bit of a read. A couple of days ago I decided to have another crack at it and do it properly this time.

Zetro is an absolute Gem when it comes to advice, and he suggested that I take my time with the hot air on the stubborn welds, starting on about 150 Deg C for five minutes and gradually working up whilst liberally applying the flux. Taking that quite literally on board I started at 150 for 5 mins, increasing to 250, then 300, and finally 350. This was the magic number and I was able to get the solder to flow nicely and do a proper job rather than the embarrassing hack weld I had applied previously.

It is the metal braid Ground that was the victim of my bodge, this is it after the proper repair.

I also decided to properly attach the power cables which I had previously performed a cable to cable weld. Using the same technique as before I removed the old cable and soldered in the new cables from the other side. I also performed complete continuity tests on all connections and got good positive results.

I did use a large amount of flux, and there is some residue and I did have a good clean up job to do afterwards. As you can see there was some scorching to some of the PCB. Hot Air obviously has a knack to it, and I was careful to keep it moving about so as not to damage anything. I wasn't always successful obviously.

I also took some time to check and re-check the seating of all logic board chips and cables and discovered that I had mis-seated the audio cable connector back onto the power board.

This is viewed from the top, but is only really accessible from the other side underneath the Tube. It is really awkward and fiddly to seat them correctly, but with a little perseverance I managed to get the audio connector on properly.

I plugged her in and powered her up. This time the logic board came up no problem, I could clearly hear the startup sequence and game audio but could see no response in the monitor.
Checking round the back visually I could see that the bulb at the back of the tube was only glowing slightly. However, I decided to call it a night.

Next step will be to be check the voltages, but at least, for now, I know the logic board is still viable.

 

[tokyoracer]

Nice one, always interested in one of these. Saw one at my local car boot sale in Kessingland (Suffolk) but the bloke wanted £25 for it. Didn't know the true value of these things until recently.

You could say im kicking myself now lol.

Best of luck anyways, will be watching this thread with keen interest.

 

[Photon]

If you haven't cleaned it yet, I can recommend clipping off half of the strands on a non-static paintbrush. If the dust has stuck a little it's good for a first clean, to get it decent.

You should unseat the chips, to check the state of the sockets if nothing else. If you have electro-cleaner you can carefully spray just a little of it on the sockets, using the 'straw'.

The white traces to center sounds like either the beam failing to turn off properly (should be off while moving, on while drawing). If turning the brightness pot doesn't fix it, and the pot is okay, then look for a burned out or shorted driver transistor. (Or solderpad on same). Should be near the screen cable connector.

I can only give generalizations as I've only looked at arcade vector PCBs, sorry.

If you're ambitious or if the dirt is stubborn, you could remove all the socketed stuff and dishwash it manually, like a plate. Dry it vertically using a fan overnight in a warm room.


But if it all works except for some bugs, I'd suspect a solder joint or failed component. But of course you have to be able to see what's wrong with it

 

[desiv]

Great job. Keep it up...
I love my Vectrex, and (knocking on wood) it's been good so far, but repair info is good for all!!!

desiv

 

[User1301]

Excellent job there r0jaws and glad to see that at least some of my old Vectrex is getting used. Let me know if you get it working in the end as I think I may still have one of those multi cart's for it that has a pile of games on it that I can send you.

Cheers

John

 

[r0jaws]

Thanks John, I may take you up on that when I get this going.

Had a few minutes tonight so checked the voltages. The -5 and 13v looked pretty much spot on but the +5 was reading a little low at +4.66
I don't think this is the reason, but I have a few more steps to go down.
Still a puzzler though.

 

[r0jaws]

A bit more work this evening. In order to rule at a flaky PSU I swapped the installed one out from my spare.
It isn't that complicated but it does require completely dis-assembling the unit and some soldering.
It took about an hour and a half in total to get it all back up and running again.
Firing her up, still results in a working logic board but no screen. The voltages are much better though giving solid +5, -5, and 13v so at least that is an improvement.
The bulb at the rear of the CRT tube is still very dim, and I need to investigate if this could be the source of the failure. Unfortunately I know very little about CRT operations, I'm going to have to do some reading here.

 

[Throttle]

Hi
r0jaws i recently got a Vectrex given too my son who's only 6 and tbh id never even heard of one, even though i've been into gaming for years anyhow....

I now have the same trouble with the Vectrex that you have or had in your last post, My screen was working fine then suddenley when it was being switched on the screen wasn't coming on yet i could hear the speakers playing the music and sound effects so assuming psu is fine.

I have took the rear cover off and the bulb at the rear of the CRT is only lit up very dim, so i wondered if you managed to get your screen back up and running and if so what you did too fix it ?

Throttle

 

[JACK98]

Apologizes if this has been mentioned.Site here has service manuals if any use.
http://www.playvectrex.com/