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My cockpit pole position went out. The mods for the ar2 's had already been done. When disconnected from the pcb's, both supply's show 5 vdc. When connected to the boards, one board shows 5 vdc and the other drops to 1.5 vdc. I checked the voltage across the sense plus and sense - and the same shows; 5 vdc disconnected and 1.5 vdc under load on one board only. Does anyone know if this is something common? The atari sense thing has always thrown me off.

Wonder if the grounding bulletproof thing has been done on the boards.. Just spitballing


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Yes. That was the AR mods that I mentioned. It had been working and then one day it was just off. I don't see anything obvious. There had been quite a bit of work done prior to me owning this machine. I picked it up early this year.

Ok. So the mods on my pcb's are for the gnd and 5 vdc (see johns arcade episode bulletproof pole position). I have been checking forum's etc, looking for common problems and found this:http://www.ukvac.com/forum/fixed-ar2-5v-line-problem-info-for-newbies_topic343028.html
It looks as though there are two types of mod's: one to help supply 5vdc to the pcb's around the edge connector to the test points, and another to bypass the sense from going through the pcb and causing issues. I do not yet have the sense mod. I will add it this afternoon and will update the status.
Again, any thoughts on this issue are much appreciated.

what board is dropping to 1.5Vdc. is it the video board or the cpu board. if possible try to switch the AR2's around and see if anything changes.

They are both dropping. They drop when the pcb is connected to the ar2.  The ar2 shows 5vdc while not connected to the pcb. I have looked on the Internet a bit wondering why the 2 ar2's look different. It seems that there were different versions of the ar2 made. At some point these ar2's must have been replaced as I have what looks like an a035435-02 and an a035435-04.
I am about to make the sense mod jumping pin 1 to 2 and 3 to 6 at j7.
http://www.stickycarpet.com/pinx/ar2mods.html

thoughts?
(I will try the swap first. Thx)

I advise you to do the sense mod properly by adding wires to the sense wires and hooking it up to a test point on the board. I think sense mod that every one does is poor

I swapped the ar2's and I am now getting 5vdc on the pcb. I have looked on the Internet and the only sense mod I have found is jumper in the solder side at j7. I am not familiar of another way.what do you suggest?

Do you mean the test points on the pcb?

Update:
Sense mod accomplished. Output from ar2 not connected to the pcb is 5vdc.
Power on test points at the pcb connected are 1.5vdc.

Time to check components.

http://bitslicer.tripod.com/ar_sense_mod.htm

I am not a big fan of the sense mod as is published. but do keep in mind you can't set the power supply to +5V and only measure at the supply. You have to plug the game in, and try to adjust it to 5V at the PCB. Pole position takes up a ton of power and can easily drop 2-3V in the cabling.

Ok, I have to admit. I cheated. I put my ARII from Centipede im to pole position. It is working awesome. I am waiting for the rebuild kit abd I was jonesing for my sit down pole position. I have some othe issue I will post shortly. I will keep the rebuild updated.

Just a side note. The sense mod doesn't bypass the edge connector, it only stops the sense adjustment from happening. When the circuit senses low voltage it apply's more and more until it burns/ melts the edge connector. Grounds and +5 strapping on all points on both boards for sure protects from any issues but the sense is a must on all ARII psu's.

Yes. Thank you. My pole position has +5  and gnd connections soldered directly to the board with their own connectors for each board. Its one more connector to unplug but they are unique so they can't be mixed up between boards. They are wire tied to the edge connector bundle for ascetics.
I ran the game for 10 hrs checking voltages, the edge connectors, r29, and r30 for heat increases (with a temperature gun). Everything was cool. The voltage drop from the power supply to the return sense is less than .2 volts. Not perfect but its running awesome. I had some issue with the game that i had posted on here before. Those issues are gone.
My learning curve is the difference between the arii's. (1,2,3,4...) i have a 2 and a 4. Both 5 connector. Pole only has 3 connections but centipede has 5. A 2 came out of centipede which is what was in my pole along with a 4. I believe i could use a 1 which only has 3 connectors. (All are populated differently)