Vectrex Monitor Modification

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sync24
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Post by sync24 » Mon Feb 18, 2019 8:01 am

bitSmasher wrote:I might've confused things, was rushing a bit when typing the last post.

What I'm proposing, is could a separate circuit be used to mimic the spot-kill function - preferably in Euro format, and with lower frequency threshold so we can still have very slow movement.
So disable spot-kill in the Vectrex, but ensure whatever signal is being sent to it (namely the Z) is processed to prevent burning the screen.

Maybe a pair of Slope Detectors monitoring X and Y signal, that has a gate that goes high when signal is steady (ie, DC or 0V)
Feeding in to a logic (NAND?) which controls a VCA on the Z.
If X and Y are both steady, then Z is switched off.

:despair:
Or I'm just over-thinking, and should just take the easy way and accept that I'll burn the screen...
aah, I see - yeah, I have used an env gen to kind of mimic the spot-killer circuit myself, so the Slope Detectors make sense.
btw - I am more an 'in-practice' person than 'in-theory' - so I have to see what happens by doing rather than thinking or writing about it... so I'd say try it and see if you don't burn yr screen ;-)

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sync24
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Post by sync24 » Mon Feb 18, 2019 8:08 am

bitSmasher wrote:Regarding using the game output - it was BCB's video that inspired me.
My idea is that game output could be taken and paralleled, so driving euro as well as the internal screen.
A second set of switching jacks would be used, if you wanted to drive the screen.
Essentially like a "half normalled" patch bay connection.

Image

Could I expect the Vectrex to drive both internal screen and external modules, without cooking it? Assuming most Euro modules have a high enough input impedance...
cool - carrying on my in-practice way of doing things, initially I had attenuators on the inputs to the Vectrex as I was concerned I might cause some problems sending whatever levels Eurorack sends. But then after a while I didn't bother and I didn't damage anything.
So, I would just try attenuating the signals coming out of the Vectrex and see what happens.
Alternatively, and this is kind of new to me... measure the voltages coming out of the Vectrex game board.
(I say new to me because I was trying to understand the LZX Cadet stuff and ended up hooking up my volt-meter to various outputs, then I had that 'ah-ha!' moment!!! rest assured this is not my field of expertise, but I have realised (more than learnt) stuff, such as stuff about scaling up or down voltages)
I still feel :deadbanana:

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tau_seti
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Re: Vectrex Monitor Modification

Post by tau_seti » Mon Mar 02, 2020 11:54 am

I had a Vectrex modded for me yesterday. I respect everyone who can DIY it, but that’s not me.

The directions for how we did this are here. http://www.lumpybanger.com/blog/hacking-vectrex

I’ve had beautiful results, BUT I also hear a very high pitched squeal. I do not believe that it is the speaker, but rather it is something inside the Vectrex vibrating. I do NOT hear this when I play games (we installed a switch for the signals) however I do hear a hum of sorts that may be similar. What is causing this and how can I avoid it? I am afraid it will damage the Vectrex, but I’m even more afraid it will damage my hearing.

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tau_seti
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Re: Vectrex Monitor Modification

Post by tau_seti » Tue Mar 03, 2020 10:16 am

Here is an example. The sound can be a lot higher pitched though and that’s where it bugs me.

Could it be leaking through the speaker somehow?

[bbvideo] [/bbvideo]

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mckenic
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Re: Vectrex Monitor Modification

Post by mckenic » Tue Mar 03, 2020 1:12 pm

Hello mate!

Glad you got a Vectrex!
I *think* what you are hearing is the audio you are putting into it... at least thats what I thought when I had mine apart to install jack sockets. In the vid below there is no audio going anywhere besides the vectrex so if you turn the video up really high (sorry for the poor quality I was after the visuals) you can hear the sound that the modular is making through the vectrex. There is nothing loud so its safe to turn up.



With your example - if you mess with the pitch of what your sending it (I'd imagine to the z input?) does the high pitch whine go?

Anyway I'll email you if I can be any help.
Oh and you need this too:



:hihi:

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tau_seti
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Re: Vectrex Monitor Modification

Post by tau_seti » Sun Mar 08, 2020 7:14 pm

Yes, sir! The other day I was playing the sequence from Pink Floyd's On the Run (E3, G3, A3, G3, D4, C4, D4, E4 @166bpm) through the Vectrex and could clearly hear it, although it sounds filtered to only include sound above 7000Hz or such, profoundly irritating and painful!

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