Filter Board?

jgeiger

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I have a couple of Atari cabs including Star Wars and Crystal Castle that have filter boards that connect multiple board or just a single board. On my CC I was told to take off the filter board and run it without and it works just fine. So, that leads me to the question of what the purpose of it is and how it works. Any info?

Thanks.
 
I believe it was supposed to reduce noise along the data and voltage lines so as not to harm the pcbs.
 
I believe it was supposed to reduce noise along the data and voltage lines so as not to harm the pcbs.

The filter boards may also be in place in order to reduce the amount of electromagnetic noise that's radiated by the cabinet. These cabinets do have a certain emissions standard that they have to meet, and one of the ways to put a lid on emissions from a line is to run it through an inductor (basically, a metal ring with a wire wrapped around it. See the wikipedia article on inductors).

The idea is that the inductor (if kept small enough in value) will sort of take the edge off the signals (round out the square waves, slow the transitions ever so slightly). This will change the EM signature of the whole mess, hopefully making one meet whatever standards are applicable.

Putting them on a separate board has advantages in that you don't have to re-spin your main PCB, so you can get to production sooner.

The filter board was placed there in order to try to fix some issue. Whether it succeeds or not is an interesting question, but it definitely adds one more point of failure, and some folks recommend removing them for certain games. Unless you have a reason to do so (like your board is flaky, or the game is widely known to have problems with the filter board) I'd leave it in place.
 
Agreed, I think this is good advice:

The filter boards may also be in place in order to reduce the amount of electromagnetic noise that's radiated by the cabinet. These cabinets do have a certain emissions standard that they have to meet, and one of the ways to put a lid on emissions from a line is to run it through an inductor (basically, a metal ring with a wire wrapped around it. See the wikipedia article on inductors).

The idea is that the inductor (if kept small enough in value) will sort of take the edge off the signals (round out the square waves, slow the transitions ever so slightly). This will change the EM signature of the whole mess, hopefully making one meet whatever standards are applicable.

Putting them on a separate board has advantages in that you don't have to re-spin your main PCB, so you can get to production sooner.

The filter board was placed there in order to try to fix some issue. Whether it succeeds or not is an interesting question, but it definitely adds one more point of failure, and some folks recommend removing them for certain games. Unless you have a reason to do so (like your board is flaky, or the game is widely known to have problems with the filter board) I'd leave it in place.
 
The Atari football I just got has a filter board and the edge connector on it was pretty burnt up and causing sync issues. I have since removed the filter and monitored the voltages to the main pcb which look good. It seems to run fine. The filter board on my star wars has been removed as well and works great.
I agree though, if it is working fine with the filter board, I wouldn't mess with removing it.
 
Anyone got a spare filter board i can have? I actually need one. Not for the intended purpose, but because i am playing mad scientist right now and REALLY need a filter board
 
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