Mini The Invaders screen shake.

[Lurch666]

I'm building a mini Zac the invaders cab since I don't have room for a full size one.
Hopefully going to show the build once it's finished but at the moment I have an issue with the CRT screen shaking because of the sound FX.

If I have the speaker disconnected there is no screen shake and I have used shielded cable on the composite signal to the tube.
Is there anything else I can do to reduce the effect of the sounds on the screen? I've made the wires between the PCB and the speaker short to try and reduce interference and long to move the speaker further away but neither had much effect.
Everything is pretty cramped in there but hopefully I can minimize or eliminate the interference somehow.

 

[stevebm1]

you used to be able to buy magnetically shielded speakers,have you tried one of those?

 

[Lurch666]

Since I tried with a long lead and the speaker a meter away and still got the shakes I figured it's nothing to do with the speaker.

I think I've found a solution though. If I pick up the sound signal before the amp and use my own amp the shake goes away so I'm hoping a little ebay single channel amp will do the job better.


I always wondered why whenever I saw a the invaders on youtube or in the wild (RGP had one) the sound was always low and it disappointed me because one of the things I like about this game is the invader hit sound.
Maybe because it's an inherent issue that if you have the sound anything other than very quiet you get screen shake?

 

[TheDaddy]

I was wondering if the shaking was all the drinking you do lol.

On a serious note it Could be leakage on the amp circuit.

Dave.

 

[Lurch666]

Not so good at fixing audio issues so will stick to the simple solution.

 

[TheDaddy]

Not so good at fixing audio issues so will stick to the simple solution.

If it works its a fix either way mate.

Dave.

 

[Mr20to5]

I always wondered why whenever I saw a the invaders on youtube or in the wild (RGP had one) the sound was always low and it disappointed me because one of the things I like about this game is the invader hit sound.
Maybe because it's an inherent issue that if you have the sound anything other than very quiet you get screen shake?

I own an Invaders and the sound is low for a couple of reasons but not what you think.

Firstly unlike the other makes, there is no grill cut out for the speaker to sit behind and blast out it's thunderous sounds.

Secondly, where it is originally positioned makes no sense as it os basically muffling all it's sound.

Moving the speaker completely transforms the sounds it makes.

 

[lewinskys]

You can try a smaller speaker, or even 2 small speakers in parallel. Not sure where you have the speaker mounted, but you can also shoot the sound down through the bottom of the cabinet if there is an air space to allow the sound to come out from underneath. Then put a metal shield over the speaker to block the magnetic interference.

 

[Lurch666]

Still trying to solve this one.
It took ages for the small amp to arrive but it's made no difference so the shaking isn't down to the onboard amp.
If I keep the external amp connected but without a speaker I get no shake but no matter what I do with the speaker,move it far away or encase it in a tin the screen still shakes.

The speaker I'm using is the one that was inside the mini TV I'm using for the screen so how the hell did it not interfere with the normal TV signal when it was being used to watch anything?

Will try two speakers in parallel next.
Also wondering if a bigger speaker might help for some obscure reason?

 

[Lurch666]

I now know why I'm getting screen shake but not sure how to solve it.
It's because I'm running the 12V for the CRT from the same jamma PSU as the game.
Just tried running it with the CRT running from a separate PSU and no screen shake.

But since it's a mini cab there not much room inside. Either I will have to find a small separate PSU just for the 12V or figure out a way of isolating the 12V going to the PCB from the 12V going to the CRT.

 

[Bods]

Just get a small 12V adaptor to power TV if it doesn't like being powered from jamma one, just need one with correct amps and connector

https://www.ebay.co.uk/itm/40379159...uGlP0MnYQRDjR2OxHBkngUwG8s|tkp:Bk9SR9y2qOLDZA

 

[Lurch666]

That's exactly the type I have ordered.
Hoping it's nice and small so it will fit.

 

[Georgian2]

Is the monitor powered by the same 12V that is used for audio amplifier? If yes, you need more power on the 12V line.

You can lower the speaker wattage too and leave more power for the monitor.