Got vectrex with the white dot problem but...

[omnedon]

The standard fix in the FAQ does not solve the problem. The FAQ says to check the solder joints on the power connectors that go from the bottom PCB to the side PCB. I reflowed the solder there, and a few other places too, no go.

Great sound. Tiny white dot. Any other ideas? A cap kit maybe?

I really know nothing about monitors/tubes, but I may be able to learn if I have to. Googling seems to get me more about the standard fix.

Any ideas? FABombjoy? johnsoper? Bueller? :)

[chadtower]

A cap kit could be it, check the power going into the monitor as well. I'd make sure it's getting proper voltages on X, Y, and Z before I went and ordered a cap kit, though a cap kit could certainly be the issue.

Does a Vectrex have the same type of spotkiller that an arcade XY monitor has? An arcade monitor will shut its tube down if either X, Y, or Z isn't receiving enough voltage.

My guess is that it does not since the spotkiller is intended to prevent the tiny white dot and therefore burnin of the tiny white dot. A static vector image will burn the tube in a real hurry.

A cap kit is EASY. I have never tried to find one for a vectrex, but if they do have a preassembled kit, it will come with a baggie of caps and a map. Replace all of the caps on the board that correspond to caps in the bag. That's all there is to it... but be sure you learn how to discharge a monitor before you go and try it. That is very important. Don't electrocute yourself.

[omnedon]

To discharge it, where exactly do I put my tongue? LOL

I've read that a Zentech or something place has Veccy cap kits.

thanks so far!

[AlanD]

and make sure you observe polarity putting the new ones in. I believe they make nice popping noises and let all their smoke out if you put them in backwards - not that I ever had that problem :)

[FABombjoy]

Hmm... Do you have an o'scope yet?

If you've got a dot & the game is running (evidenced by the sound), you've gotta start near the DACs and trace from there. Is the dot in the exact center and seem to do nothing when you hit the reset button?

Be sure the X/Y/Z cable has good contact too. I fixed a 'broken' Vec once just by resoldering the Z pin. If the cable is plugged in wrong it won't work either.

I'd hold off on a cap kit for now. Zanen has the kits, but unless they've updated them, they're not entirely accurate.

[FABombjoy]

Oh yeah, and read 'no vector' section at the end of this:

http://www.playvectrex.com/shoptalk/vecguid.pdf

[omnedon]

No scope yet. x_x

When I hit reset, the white dot goes up, and to the right.

....up, and to the right.

....up, and to the right.

....up, and to the right.

....up, and to the right.


LOL

[chadtower]

Get the service manual, if it's not on the net I believe Sylentwulf has it.

You won't be needing an oscilloscope. That's overkill, you can do anything necessary here with a multimeter.

If the white dot actually moves, I would start with the DACs, and check the op amps too.

Head over http://slot-tech-ftp.serveftp.com:8080/techdept/ and spend some time reading about monitors. It will tell you everything you could need to know.

[Chunky]

it is fixable, i have had a few that i sold to sean kelly and he turned around fix and sold them.

anyone know the correct fix for the buzzing sound?

[FABombjoy]

anyone know the correct fix for the buzzing sound?

3 methods:

1st is to upgrade the audio cable to shielded coax & remove the existing grounds between the boards, using the coax shield as the only ground for the CPU board

2nd is to preamp the audio signal in order to boost the signal level over the noise floor.

3rd is to cover the speaker in packing tape.

I've done the 1st method a few times and it helps out alot, but doesn't completely eliminate it. Never tried the others.

[omnedon]

Thanks for the pointers. Will do, and will post progress.

[blue lander]

My Vectrex had the white dot problem, and I fixed it by replacing the 6520. I believe I bought the replacement chip from www.therealbobroberts.com, but if you wanted to you could grab one from an old Commodore 64.

A word of caution when working on the Vectrex: The traces seem to like breaking and peeling off. When I removed the 6520, I took a bit of the circuit with it. It was a pain in the butt to repair the damage I did.

[FABombjoy]

FYI the 6522 was used in the VIC-20. The C64 used the 6526. Based on their functions and pinouts, I doubt they're compatible devices.

The 6522 also controls sound and input, so if it were broke it could possibly take those out too. Out of curiousity, were you able to blindly play your Vectrex?

See the document at:

http://www.playvectrex.com/designit/chrissalo/via3.htm

It tells you what pins control what vector chips. Could be useful for 'white dot' debugging.

[blue lander]

Whoops, you're right. It is a 6522. I fixed the Vectrex so long ago I don't remember the specifics anymore. I could have sworn the FAQ I read said you could grab the chip from an old C64, but perhaps they said VIC-20.

With mine, you could hear the game playing but all you got was a white dot in the middle of the screen. Sometimes the dot would get slightly wider, but that was it. I don't recall if it'd take input from the joystick or not. Replacing the 6522 made it work perfectly.

I'd also suggest that while you have your Vectrex torn to pieces, that you take the opportunity to shield the speaker wires to diminish the "Vectrex buzz". You might as well while you're at it, and if you don't it'll start annoying you after a few weeks and you'll wish you had.

[FABombjoy]

I'd also suggest that while you have your Vectrex torn to pieces, that you take the opportunity to shield the speaker wires to diminish the "Vectrex buzz". You might as well while you're at it, and if you don't it'll start annoying you after a few weeks and you'll wish you had.

Yes, I agree completely! Every time I hear a Vectrex with the original audio, I am amazed at how loud that noise is.

I experiment once with simply replacing the speaker wire with shielded coax, but the effect just wasn't as good as when you cut the existing grounds & use the coax shield as the CPU board ground.