Atari SENSE mod - summary?

Steverd

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After reading a bit on the Sense mod, is it basically:

On the back of J7
solder a wire:
between pins 3 and 6 and then
between pins 1 and 2

Is that it?
Sounds super easy!
Has anyone also replaced R29 or R30 with a 100ohm resistor instead of the normal 10ohm?

Thank you,
 
There is actually more than one way to do it. (See pic).

Darren Harris
Staten Island, New York.
 

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You might be thinking wattage, not ohms
When the sense mod is done, this can't repeat

Might be some mis understanding.

From: http://bitslicer.tripod.com/ar_sense_mod.htm
You can also swap out the 10 Ohm resistors R29 and R30 for a higher value such as 100 Ohms. This allows the SENSE lines to handle more push from the AR, but this is more of a stop-gap measure.
 
do it right, replace the edge connector instead.

Doing that tonight!
I am using the Bob Roberts Edge connection repair kit.
Then I'll replace the R29 and cross my fingers for another power-up!

I do like to leave as much original as possible, so I'm not sure yet, if
I want to do the SENSE mod or not..
 
Doing that tonight!
I am using the Bob Roberts Edge connection repair kit.

Ugh, not that monstrosity...

Make sure it'll fit before you start installing it. It lengthens the board, and your back door may no longer go on.

IMHO, that remedy is only appropriate for severely burned edge connectors. Yours is only lightly singed on a couple of pins. Should be able to fix it in situ without resorting to such extreme measures. If the fiberglass below the trace is compromised, remove the trace, fill & level it, then bond on a new strip of copper. Bit_slicer has a nice video of the process on youtube, IIRC.

And the problem is more likely in the OTHER connector; the plastic housing the plugs onto that edge connector, with crimp-on pins in it. Replace those pins! Check the housing to make sure it's not deformed.
 
Ugh, not that monstrosity...

Make sure it'll fit before you start installing it. It lengthens the board, and your back door may no longer go on.

You are completely right about this! It adds a little over an inch the the end of the PCB, I will test it first, then decide how I will do about the fix.
 
Ugh, not that monstrosity...

Make sure it'll fit before you start installing it. It lengthens the board, and your back door may no longer go on.

IMHO, that remedy is only appropriate for severely burned edge connectors. Yours is only lightly singed on a couple of pins. Should be able to fix it in situ without resorting to such extreme measures. If the fiberglass below the trace is compromised, remove the trace, fill & level it, then bond on a new strip of copper. Bit_slicer has a nice video of the process on youtube, IIRC.

I have loads of respect for Bitslicer's method of repairing this, very hard-core. However....I have one big issue with it:
It sets you back 30 years. The board is back to the same mistake that Atari made:
Using an edge connector to carry too much current.

Of course the cab will only see home use only (well for most of us) from that moment, but in theory the same process will repeat.

The GND pins (A and 1) on my Lunar Lander PCB are burned and someone "fixed" it in the past. It looks like a mess. Because it's the GND connection I am thinking of running a wire with a crimp connector to the GND test point on the PCB instead. Apparently somebody had the same idea on my LL cab (NOTE => cab and PCB are from DIFFERENT sources !!!!) and hacked in a female crimp connector wired to both the GND wires that run to pin A and 1.

This would give the GND a "thick" connection, capable of handling much more current than the edge connector. It's prettier than BR's solution and more safe than Bitslicer's....
 
If the edge connector is clean and the pins have been replaced, then all that is needed is A) the disabling of the sense circuit, and B) the running of extra +5V and GND leads to the test points.

Darren Harris
Staten Island, New York.
 
The GND pins (A and 1) on my Lunar Lander PCB are burned and someone "fixed" it in the past. It looks like a mess. Because it's the GND connection I am thinking of running a wire with a crimp connector to the GND test point on the PCB instead. Apparently somebody had the same idea on my LL cab (NOTE => cab and PCB are from DIFFERENT sources !!!!) and hacked in a female crimp connector wired to both the GND wires that run to pin A and 1.

This would give the GND a "thick" connection, capable of handling much more current than the edge connector. It's prettier than BR's solution and more safe than Bitslicer's....

This sounds interesting, can you post a photo of it?
 
Wait, what's part 'B'? I didn't see that on: http://www.stickycarpet.com/pinx/ar2mods.html
Is there info/photos on a different site?

Thanks,

Yeah, that page only mentions half of what you should be doing. By running leads from the ARII PCB to the main PCB you are "widening the highway" so that the current that the edge connector pins couldn't handle has addition options and as a result you won't have to worry about it burning up the pins at the board edge.

So disabling the Sense circuit is only half the battle.

Off hand I don't know a page that shows exactly what points on the ARII PCB are to be connected to what points on the main PCB, but I'm sure someone will chime in. (You can use a molex connector so you can connect and disconnect when needed.

What game are you working on?

Darren Harris
Staten Island, New York.
 
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So disabling the Sense circuit is only half the battle.

Off hand I don't know a page that shows exactly what points on the ARII PCB are to be connected to what points on the main PCB, but I'm sure someone will chime in. (You can use a molex connector so you can connect and disconnect when needed.

What game are you working on?

Still haven't found the page..
This is for my Battle Zone machine.
Haven't had time to work on it this week. But it does look like the molex pin at pin #2 is bent in where it wouldn't be making good contact. Probably causing the burnt #2 pad on the PCB. I'll fix that this weekend.
 
A couple of comments from my experience.

Burned fingerboard. I have 2 Pole Positions and a Tempest in my game room now with "Bob's Method" of repair. No issues with any of the doors closing. Personally its my preferred method. I would not tin with solder or overlay a bad pin with copper tape. It fattens the fingerboard and over stresses the pins in the harness. Not a super big deal if you only have that one board in the game. If you try to test another board in the cab it will be flaky. I never let anyone test a board repaired with tinning or tape in my cabs because I don't want my harness messed up.

Edge connector on the harness. Re-pin all of the ground and positive voltage pins as well as the pins involved in the sense lines. If the path became hot enough to burn the fingers on the board the pins are in just as bad a shape.

Sense Mod. I don't do it. I have actually reversed it. I currently have 6 Classic Ataris in my game room. All have nicely maintained finger boards, edge connectors, and power supplies. None are sense modded and every one runs like a top..to include 2 Pole Positions.

ARII. Rebuild it. At a minimum cap it. Power the game up with the game board disconnected and set the 5V. Power down, connect the board, power up, and re-set the 5V. I am assuming the fingerboard and pins have been addressed.

Pole Position. When I re-pin the 5V lines I pull them from the edge connector, tie them together, run short extensions to repopulate the harness, and run a drop that I use to direct wire the test points. Same for the ground lines. I solder and heat shrink tube the connection. I loop all the test points, 5V and Ground, and tie the board and the harness side together with a Molex connector. Both boards get the same treatment. I ALSO fix the fingerboard. So, long term I have a parallel 5V and ground path to run the game. I can also swap in another board as, since the harness is up to snuff, the cab will run without the parallel path connected just like it did back in the day. I can swap in any spare board or test a board for someone.
 
Excellent posting, fully agree, apart from that I check the AR1/2 caps before replacing them and that I would do all the pins (untill know I replaced the entire connector with a solder version). I could actually SEE the difference on my MC cabaret, the color guns simply got a little bit more power to them because of this, the screen was a little bit brighter because of it.

I had the same idea of doing parallel power supply connections.

I can also confirm the issue with the thicker edge connectors messing up the pins.

One question, the new pins, what do you use to crimp them ?
 
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