Old Tech: Space Invaders Motorola XM501 : need caps explained

Black Matrix

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Old Tech: Space Invaders Motorola XM501 : need caps explained

Hey all,
I have a Space Invaders monitor that I am looking at trying to make right. At the moment, the game just doesn't seem to focus, and the bright is off, it will pulse white at times, cut out sometimes, but will come back up if I power down, its very problematic but it does work. I'm sure it could be a great many things causing the problem: cracked flyback, bad pot, leaking HV somewhere.....

Anyways, I performed the Bob Roberts cap kit on it. No improvement. But I did notice that when either the Bright pot or Contrast pot is turned up and down, the picture would be perfect when it was adjusted just so. And then would the image would dim. Anyways, my friend suggested that I replaced all the other caps that weren't included with the kit. The pots that aren't supposed to go bad.

So I'm looking on digikey to try to source these parts. The manual calls the caps Mtzi Poly and Polyester with a Mylar thrown in for good measure and Lytic.

I pretty much assume Lytic is electrolytic polarized caps as most where the ones in Bobs kit.

When I search for Capacitors on digikey, the choices are:
Aluminum
Arrays
Ceramic
Electric double layer supercaps
Film
Mica and PTFE
Neobium Oxide
Tantulum
Thin Film
Trimmers and Variables

So my question is, what modern day replacement corresponds to these caps used on the old B&W monitors-where should I be looking for these Polyester and Mtzi Poly caps on Digikey. I hope thats not too stupid a question.

And most were Axial (it it helps to know) although radials might fit better since most were mounted upright and bent so both ends were pointing down.
 
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You should only concern yourself with replacing the electrolytic capacitors. One special electrolytic is NOT usually included in the capkits: the tall metal "twist prong" can style multi-section electrolytic capacitor. This should get replaced as it is now 35 years old. One or more of it's sections are probably going/gone bad.
 
So my question is, what modern day replacement corresponds to these caps used on the old B&W monitors-where should I be looking for these Polyester and Mtzi Poly caps on Digikey. I hope thats not too stupid a question.

I agree with Ken....these other kind of caps rarely go bad. For your knowledge.....Polyester (and mylar) are both a type of film capacitor. Mtzi Poly is short for metallized polypropylene. Polypropylene is also a type of file cap.

Edward
 
Where can I find one...Whats a good source for these. I just wasn't sure where to find the 4 rating can or do you use 4 individual caps. And if the other can cap is available, I may want to pick it up as well.

You should only concern yourself with replacing the electrolytic capacitors. One special electrolytic is NOT usually included in the capkits: the tall metal "twist prong" can style multi-section electrolytic capacitor. This should get replaced as it is now 35 years old. One or more of it's sections are probably going/gone bad.
 
You likely won't find a "new" multi section can cap like that. If you do, it will be just as old as the one you have now and likely in worse shape just from sitting idle on the shelf. What does this mean to you? Well...it'll be so degraded internally that if you install it and then throw the power to it, it will short within a few seconds and blow the main fuse. The cap just may make you well aware of the situation by exploding like a firecracker and making a big mess of your chassis...

You can replace that cap with seperate radial caps and secure them to the frame with zip ties or acid free (electronics grade) RTV silicone. Be careful with how you wire them in, and make sure you don't just tie the new caps into the existing tabs on the can cap. Remove the wires from the can and connect them to the new caps. Observe proper polarity.

Some older caps have non standard values, such as the 5000u can. Just use the next closest standard value (4700u) and match the voltage rating. Its OK to go higher in voltage, just not lower.
 
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