Vectrex with problem need advice

[vsl]

Hello,

I bought a Vectrex with a stated problem: a white dot and no sound. When it arrived, I replaced the 2764 EPROM, the two 2114 RAMs, and the 6522 PIA.
The sound came back, and the white dot is no longer just a fixed dot, which is visible in the video.
But I got to this point and I can't find the culprit, please help and advise.

Thanks !

 

[big10p]

Do you have a scope? Hook it up to the XY output from the logic board. This will tell you if the issue is on the logic board or the deflection board.

 

[vsl]

yes, this is output from logic board (probe x1):

 

[Georgian2]

yes :View attachment 64154View attachment 64156

You need XY mode in order to see if you have the same image like on your monitor or something else.

 

[big10p]

yes :View attachment 64154View attachment 64156

Use two probes and put the scope in XY mode. Digital scopes aren't very good at displaying vectors, but you should be able to see a rough version of the game playing. Do you have a test cart or a flash cart you can put the test cart ROM on? It will help to see if vectors are being output correctly from the logic board.

 

[vsl]

 

[vsl]

Guys, thanks for the idea! This is my first real experience with a vector system, so I honestly didn’t know about using the oscilloscope in XY mode for this kind of diagnosis. 🙂

That’s actually a brilliant trick — basically turning the scope into a second vector display and comparing what the logic board is generating with what the Vectrex CRT is showing.

I’m learning a lot from this repair already. The machine started as a silent white dot, and now we have sound and actual vector movement, so at least the patient is definitely alive. 😄

Thanks again for pointing me in the right direction — the hunt continues! 🔧

 

[Georgian2]

That’s actually a brilliant trick — basically turning the scope into a second vector display and comparing what the logic board is generating with what the Vectrex CRT is showing.

Classic CRT oscilloscopes are best for this kind of things. On most of them, one can use the Z input on the back too.

 

[big10p]

Vectrexes are usually very fixable. 🙂

 

[vsl]

Hi everyone!

Despite trying everything I could think of, I'm still having problems with my Vectrex. At this point, I honestly don't know where else to look or what else to try to get the console working. I'm really eager to finally play it, so I'd be very grateful for any advice you can offer.

Since this is a US console originally designed for 120V, I've replaced the original transformer with a toroidal transformer with a 230V input and a 2 × 9V AC output. Both 9V outputs are stable.

I've also replaced the following: 4066, 4052, MC1408, LF347, LF353, ROM, 2 × 2114 RAM chips, 6522, and LM379.

I'm uploading a short video showing how it currently behaves.

 

[big10p]

Have you tried adjusting the 2 integrator pots on the side of the logic board? Have you replaced the integrator caps?

 

[vsl]

Are these the capacitors you're referring to?

 

[big10p]

Are these the capacitors you're referring to?
View attachment 65626

Yes. They have very delicate leads. Check them over and try reflowing the joints. Try wobbling them gently and see if it affects the image.

Does adjusting the integrator pots help at all?

 

[vsl]

I inspected them, wiggled them, resoldered them, and wiggled them again. They aren't causing the problem. When I touch their solder joints underneath the board, the picture distorts in all sorts of directions, but the lines that should be dots remain lines.

 

[big10p]

What about the pot adjustments?

 

[vsl]

I've removed the logic board and I'm starting to check every trace for continuity. I suspect there's a broken connection somewhere.

 

[big10p]

Integrator caps might need replacing.

Please say if you have tried adjusting the integrator pots, or not. Last time of asking!

 

[vsl]

Yes, I’ve tried adjusting both integrator pots (R333 and R335), as well as the size controls, but the problem remains. The frames are still badly curved, the text is distorted, and individual dots appear as short lines. The LF347 has already been replaced too.

Thanks for the suggestion about the integrator capacitors — I’ll check C312 and C313 next.