Pole Position page 2

Pole Position II Upright cont...

Another p.s.u.
As i had no schematics for this p.s.u. with the help of a mate from #Jamma Kev (Outrun) over the phone, he talked me through the schematics and i went through each of the circuits of the p.s.u. with my multimeter and this showed that the thermal fuse in the transformer was dead. Obviously i needed to source another p.s.u. where upon Steve at Swallows came to the rescue again. It is actually off a Missile Command and as you can see it looks almost identical......

Another p.s.u. cont...
....Untill that is, you turn it over. The wiring into the transformer, is identical, but the wiring coming out is different. Again i had no schematics for this either. So over another lengthy phone call
Kev (thanx again dewd) talked me through both sets of schematics and by using the 15 pin molex plug from the PP2 p.s.u. i converted the wiring to the PP2 pinouts, luckily both the p.s.u.'s gave out the same voltages, the only difference being for the monitor power. On the PP2 its two feeds of 60 volts ac and on the Missile Command its one feed of 120 volts ac.
Thanx also go to Jim (Marb) for supplying schematics for the MC p.s.u

WARNING !! again i do not advise anyone to try this, there are Dangerous voltages stored in the large blue capacitor and there is a high risk of electrical shock if you make a mistake !!!

"AR2" Audio Regulator pcb's.
Step in #Jamma technical help number 3, Chris (Kipster) Having owned a PP cockpit, he warned me about the unreliable nature of AR2's and how they can go "Tits up" and fry your game boardset. I was advised to perform a modification that would bullet proof both the AR2's.
The AR2's not only regulate the audio they also regulate the voltages being supplied to the game boardset, on an AR2 pcb there are two sensing ciruits, a 5v+ sense and a - sense, when the pcb starts to age, the regulator can think it is not supplying enough voltage and start to up the voltages it is suppling to levels that will kill game boardsets.There is a simple mod however, that will stop it doing this.
Thanx go to Kip for warning me of this problem.

Performing the modification.
First i removed the AR2 from the cab and located the 9 pin molex connector shown in the picture on the left. This is where the AR2 gets its feed in from the p.s.u.
Turning the pcb over i then needed to trace the tracks for the 5v+ and -sense to the pins in the connector shown in picture on right ( 9 solder blobs are back of molex con ), then i needed to find which pins on the connector were 5v+ and gnd. It was then a simple case of linking the 5v+ sense pin to 5v+ pin and the -sense pin to the gnd pin.

Warning i do not advise anyone to attempt this modification, if you do not know what you are doing around pcb circuitry, DO NOT ATTEMPT THIS !!
I will not be held responsible for anyone blowing up their pcb's

Performing the modification cont....
This was quite an easy modification to do, i got a new resistor i had lying around and cut off its legs and used these for the links. I trimmed these down to the right length using side cutters and then soldered them across the appropriate pins. After i had made the modification, i double,tripple and quadruple checked, that it was a tidy job and that nothing was accidentally touching something it should'nt and more importantly that i had connected the correct pins together. Once i had done the first one i then repeated the procedure on the second AR2, most Atari cabs only have one but Pole position has 2.

Other mods worth doing....
Are replacing a couple of bits that a prone to going, these are the resistor at R29 (pic on left) and the transistor in the middle of the heat sink (pic on right).

Other mods worth doing cont...
The resistor is easy to get hold of, it is a 10r or quarter watt resistor, the transistor however was a bit harder to source. I went to Maplins but they had none in and said they would'nt have any in for at least 3 weeks, but a little shop around the road from me had a bag full, so i bought 3. One for each AR2 and one to keep as a spare, these are 2N3055 transistors. Fitting these new parts,is just a case of unsoldering the old ones and soldering in the new ones, but on the transistor there are also 2 little nuts and bolts, i undid these first, then desoldered the pins, but refitted them first, as i found it hepled holding the transistor in place whilst i soldered it. I also applied some heatsink compound to the back of these, before offering them into place. You will also find that the legs on the back are offset, so it will only fit into the pcb one way (i.e. the bolt holes and the leg holes, have to line up)

Power Supply Update....
The re-wired Misile Command p.s.u worked fine, but the transformer hummed quite loudly and this i felt slightly spoilt playing the game, luckily another mate from #Jamma, Dan, came up with an origional Pole Position 2 p.s.u which works perfectly and is nice and quiet too, the only thing it needed was to remove the fuses so i could clean the fuse holders as these were filthy and not making the circuits properly.
So a mighty big Thankyou goes to Dan for sourcing this item ! Now i can keep the re-wired one as a spare.

Its Finished, Yay !!!
After doing the AR2 modifications, it was just a simple matter of fitting them back in the cab, crossing my fingers and turning it on !!
Yes it worked, well to an extent, the marquee lit up the monitor came on and the game displayed corruption, luckily, whilst beavering away fixing all these problems, a working pcb set had turned up on U.S. Ebay and i managed to win it for $52.00, so i plugged this in and Voila, i have a working Pole Position 2.
A minor thing i have to do now is change the voice custom chip from my corrupt pcb set into the working one, as the working one has Japanese speach !
This has been a quick but very frustrating and intense restoration and even though i have thanked these people already, i do have to mention them again, as this cab would not be working now, if i hadnt had their help and guidance. So step forward Kev,Kip,Jim,Steve and also Dan and take a bow, as your help has been greatly apprecitated.

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