Anybody do this mod to their ARII boards and is it recommended??
Link
http://stickycarpet.com/pinx/ar2mods.html
Link
http://stickycarpet.com/pinx/ar2mods.html
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Please post all monitor technical topics in the Technical - Videogames - Monitors section, not in the General Help section.
ARII Sense Mod
- Thread starter Robran68
- Start date
Michael Roma
Active member
I did that to a PPII that I picked up earlier this year... The ARII worked afterwards so the instructions are correct.
- Mike
- Mike
I think problems with the sense circuit are caused by bad pins on the edge connector. I've never done the sense mod to any AR boards myself, but if it is caused by bad edge connector pins, I'd rather replace them instead of doing this mod. Anyone know if this was ever an official Atari mod?
gjinc
Active member
all sorts of info on sense mods, good reading
http://forums.arcade-museum.com/showthread.php?t=41039&highlight=sense
http://forums.arcade-museum.com/showthread.php?t=38661&highlight=sense
http://forums.arcade-museum.com/showthread.php?t=38678&highlight=sense
http://forums.arcade-museum.com/showthread.php?t=29826&highlight=sense
http://forums.arcade-museum.com/showthread.php?t=41039&highlight=sense
http://forums.arcade-museum.com/showthread.php?t=38661&highlight=sense
http://forums.arcade-museum.com/showthread.php?t=38678&highlight=sense
http://forums.arcade-museum.com/showthread.php?t=29826&highlight=sense
88mph
Well-known member
+1
I have never seen any documentation from Atari promoting this practice. The AR design is good, and works the way it is supposed to if the harness, edge connector and molex connectors are in good shape. In the long run, a person is better off fixing those things and having the power system operate the way it was intended.
mspaeth
New member
Only morons hack their games in this manner, instead of fixing them properly.
bit_slicer
New member
I recommend doing the sense mod AND cleaning and/or replacing edge connectors as needed. I'd rather have AR-II power fall over than fry a board.
Biltronix
New member
Instead of calling it a "sense mod", it should've been called a "sense bypass". The sense circuit is there for a good reason. During gameplay, the amount of current drawn by the mainboard from the +5V supply varies. This changes the voltage drop that occurs over the wiring harness and the connectors. The sense leads are not supposed to conduct much current and are supposed to provide voltage feedback to the regulator so that it will output more or less voltage to compensate for the varying voltage drop. This makes sure that the +5V supply at the board remains ideal.
Obviously, soldering a bypass onto the ARII will cause a total failure to compensate for varying voltage drops and problems with the game can result. The only reason that the two sense resistors on the ARII burn is that the mainboard edge fingers and/or the edge connector contacts have worn out and have likely burned. The proper repair solution is to replace the ARII resistors and also replace the edge connector contacts (this is not hard, you just need the proper parts). If the edge fingers are bad, simply resurface them with self-adhesive copper tape (it is solderable and contains special additives to prevent oxidation meaning it stays shiney). Electronic components distributors sell this stuff.
Ask yourself a few questions...
1/ If the game worked as designed for 20+ years, would it kill you to fix it properly? If you do, is it likely to fail again any time soon?
2/ If the main power leads, consisting of multiple conductors both positive and negative, have failed at the PCB edge fingers, how long do you think that the single-lead sense contacts are going to last after you bypass the sense circuit and start dumping full game current through the sense leads?
3/ If you decide to change out the ARII board for some reason, you'll have to remember to modify the next one. If you forget, it'll fry too. ARII boards aren't all that valuable, but most collectors don't want hacked boards so you might say that modding it would reduce it's resale value a bit.
I think it is a good idea and good work practice just fix it properly and to never take shortcuts.
Obviously, soldering a bypass onto the ARII will cause a total failure to compensate for varying voltage drops and problems with the game can result. The only reason that the two sense resistors on the ARII burn is that the mainboard edge fingers and/or the edge connector contacts have worn out and have likely burned. The proper repair solution is to replace the ARII resistors and also replace the edge connector contacts (this is not hard, you just need the proper parts). If the edge fingers are bad, simply resurface them with self-adhesive copper tape (it is solderable and contains special additives to prevent oxidation meaning it stays shiney). Electronic components distributors sell this stuff.
Ask yourself a few questions...
1/ If the game worked as designed for 20+ years, would it kill you to fix it properly? If you do, is it likely to fail again any time soon?
2/ If the main power leads, consisting of multiple conductors both positive and negative, have failed at the PCB edge fingers, how long do you think that the single-lead sense contacts are going to last after you bypass the sense circuit and start dumping full game current through the sense leads?
3/ If you decide to change out the ARII board for some reason, you'll have to remember to modify the next one. If you forget, it'll fry too. ARII boards aren't all that valuable, but most collectors don't want hacked boards so you might say that modding it would reduce it's resale value a bit.
I think it is a good idea and good work practice just fix it properly and to never take shortcuts.
I had Dick Milikin repair my PPII boards
He recommended I remove r29 and r30 on my ARIIs in my Pole Position sitdown.
Also to +5s and grounds on the test connectors (which I have seen on other Atari boards)
He recommended I remove r29 and r30 on my ARIIs in my Pole Position sitdown.
Also to +5s and grounds on the test connectors (which I have seen on other Atari boards)
Black Matrix
Well-known member
Hello, my name is Black Matrix and I am a moron.
Personally, I like the sense mod and I have done it to 3 of my AR-IIs so far. The info you will get goes something like this: when the connectors go bad, the sense return doesn't register and the board turns up the 5 volts until the resisters blow. They act like a fuse. Thats over simplified I'm sure but thats my understanding. But if you don't want to replace the edge connector, you can repair the AR-II do the sense mod and and set the + 5 voltage at the board. The drawback is the old connectors could get hot because they aren't making good connection and eventually burn like pac man pcb edges often do. If your crimping skills aren't up to snuff, fix the AR-II and take your chances. If its something rare that you can't stand to loose like a star wars board, replace the connector. But it takes a lot of patience and a bit of time. Personally, I say do the sense mod and replace the connector. You'll hear a lot of static on here about being lazy, but if it works, it works. It may cost you more in the long run when the connector gets really bad.
