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The Prof's Vector Thread


Prof

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OK, starting to get into vector stuff and loving it.

 

The vector stuff so far

 

2 x Asteroids pcbs of ebay us (only pace to get them :D)

1 x LAI Vector chassis which suit a 14" tube or with a couple of parts changed, a 20" :) (Thanks to John JWG)

1 x Spacewar guts purchased from a Tim.

 

 

 

OK. First with the Spacewar.

 

PSU OK, Game pcb seemed to work. Monitor DOA.

 

First to get the monitor going. Time to scope around a bit. Seemed every transistor execpt 1 was dead in the dflection section. Also a TL081 on the x axis had no output. :(

 

Had a bit of fun trying to find replacements for them, but after sourcing from 2 companies overseas and 1 local, managed to get them all bar 2

Replaced all componets I had, powered up and a 1/4 of the picture!!

 

Finally sourced the last 2 transistors locally, poped them in and volia, full picture.

 

And witht the monitor workng I could now see the game pcb has problems. Seems to draw most vectors ok, but the ships are screwy.

 

Need to track down the fault now. But I should be able to hack it to take the asteroids signal :D.

 

Also, I would post a better pic if anyone can tell me how to get a good pic of vector monitors..

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Well done. Glad to see that you got it working. I wish I had the knowledge/brains/patience to get it working.

 

All you need to do now is buy the rest off me or build a new cabinet and you will have one very cool Vector machine with a bit of history being the first vector arcade machine and a copy of the first computergame ever made.

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Also, I would post a better pic if anyone can tell me how to get a good pic of vector monitors

ive had trouble with screen shots of standard games let alone vector stuff prof :cry

thing that seems to work for me now is to take shot from a distance, zoom in and use a flash, then i can usually get complete screen without flash blowing out as long as youve got camera on enough of an angle so as to not see flash in reflection

heres an example that i took a few weeks ago (although i was too far back to get a better screen shot :cry )

 

http://homepages.ihug.com.au/~jeffiseverywhere/tempesttest1.JPG

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OK, after aquiring a couple of vectrex's I have started to play :)

 

Story so far, get asteroids to run on a vectrex monitor

 

So, unplugged the cpu pcb in the vectrex, and have feed the x,y and z outputs from an asteroids pcb to the vectrex monitor. GOt a display, but only a small portion of the center of the screen enlarged very big!!. Right, started looking at resistor values to place inline on the x and y output. Found 39k ohms to reduce the output to a good size. Final adjustment with the monitor pots and pcb pots (x gain and y gain)

 

Right, progress, but the vectors are being clipped at the start leaving badly formed letters. Time to look at the z output.

 

Found quite a few docs about this and how the z output of the pcb is too quick for the z input of the monitor. Hmmm, time to dig the schems out for asteroids

 

Looking at the z generation area, I found that the timing ciruit was being feed by a 3 mhz signal. OK, change the main xtal on the pcb from 12.5mhz to 8mhz. WOW, draws all the vectors properly!!, Games slow as anything tho, so this isn't a solution, but an answer. Had a look at the timing shematic, and at C4 pin 13 outputs 3mhz, the signal that does the z timing, and the pin next to it does 1.5mhz.. So i put the tip of a probe between them to bridge the two pins and voila!, perfect vectors.

 

And as another note, I am running a 14" tube on the vectrex chassis too with no problems. Just had to swap the yokes over.

The first pic you can see the clipping of the vectors and the result after jumping 2 pins. which are pins 13 and 12 on C4

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