whew

[Eli the Bearded]

First a link:

Vectrex commercial reproduced on a computer nostaglia account
https://twitter.com/ComputerLove_/status/1371668449181757443

Second:

I bought a bought a capacitor replacement kit from Console5 and took
mine apart then replaced all the caps. A little bit stressful working
with that tube there. I know how to discharge a CRT, but I was still
worried about bumping it. And then more stress with traces starting to
pull off as I'm desoldering.

I replaced them all, tested it, then finished reassembly with a lot
of difficulty getting the back on (because the powerboard didn't have
the exact angle to meet the notches in the back lid) and ...

The display was messed up. Today I took it apart again and found a few
suspect soldering spots, including one possibly broken trace. I
resoldered two caps and added a jumper on that dubious trace.

Tested, it worked again. Reassembled and it still works.

Whew.

Third:

One of the reasons I choose to replace the caps is that I notice some
games don't work. Most games I've tried play fine, but Star Trek, in
particular, doesn't. The game starts up just fine, buttons work for
selecting one/two player, and for selection game. But once the game
starts, pressing any button jumps me back to game welcome screen. This
happens with both an original cart and a multi-cart version.

I've run the test cart, and other than the display being a little wider
than it should be, everything seems fine. I figured it was some part of
this game just pushing something a little far and cap refresh would do
it. No, sadly. Ideas?

Fourth:

Oh, and while I was in there changing the caps, I took a length of heavy
cable TV coaxial and liberated the braiding from it. I slipped that over
the speaker wires and soldered it to a wire that connects to the same
grounding connection that goes between the power board and the tube (the
aquadag). Buzz is not gone, but definitely reduced.

https://qaz.wtf/tmp/speaker-wire.jpg

Elijah
------
probably should have made the screen width adjustments while the lid was open

[Computer Nerd Kev]

Eli the Bearded <*@eli.users.panix.com> wrote:
>
> I bought a bought a capacitor replacement kit from Console5 and took
> mine apart then replaced all the caps. A little bit stressful working
> with that tube there. I know how to discharge a CRT, but I was still
> worried about bumping it. And then more stress with traces starting to
> pull off as I'm desoldering.

I know what you mean, I was in mine trying to poke probes at the
VIA chip while the thing was running at one point - that was a bit
nervous.

> One of the reasons I choose to replace the caps is that I notice some
> games don't work. Most games I've tried play fine, but Star Trek, in
> particular, doesn't. The game starts up just fine, buttons work for
> selecting one/two player, and for selection game. But once the game
> starts, pressing any button jumps me back to game welcome screen. This
> happens with both an original cart and a multi-cart version.
>
> I've run the test cart, and other than the display being a little wider
> than it should be, everything seems fine. I figured it was some part of
> this game just pushing something a little far and cap refresh would do
> it. No, sadly. Ideas?

The cap replacement is mainly done to fix issues in the analogue
stage (distorted display), whereas your problem would be with the
digital circuitry. It sounds like an addressing issue, possibly as
simple as a dirty or broken connection on the cartridge slot, but
also possibly one of the 7400 series logic chips that do some extra
address decoding on the logic board. I guess maybe the CPU itself
could also be at fault, or one of its address outputs is shorting
to another signal.

I don't know anything specific about Star Trek to narrow down on
which address lines would be most suspect, but it's obviously not
jumping to the address that it thinks it's jumping to (in either
cartridge ROM, or maybe the Vectrex ROM).

> Fourth:
>
> Oh, and while I was in there changing the caps, I took a length of heavy
> cable TV coaxial and liberated the braiding from it. I slipped that over
> the speaker wires and soldered it to a wire that connects to the same
> grounding connection that goes between the power board and the tube (the
> aquadag). Buzz is not gone, but definitely reduced.
>
> https://qaz.wtf/tmp/speaker-wire.jpg

Nicely done.

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