convert Pole Position to switching power supply?

[nocashvalue]

This is my first foray into pole position, and I know some of you guys are experts with this game. In trying to diagnose what is wrong with some of the games in my ultimate find I posted about earlier, I plugged this badboy up. I immediately heard gamesounds, but no picture...then I started smelling this burning smell. I quickly pulled the plug. I opened the service door and saw smoke coming from the power supply board immediately in front of me (the one attached to the back of the cab). Well, I looked and there was definitely a burn spot in an area of three diodes (or whatever) just below one of the pots. I looked at the other board and noticed that it was burned in the exact same spot!

Obviously there may be more wrong with the game than just that, but I HAVE to change out both of these boards to even be able to try and diagnose the rest of the unit. I looked on ebay and the only power supply boards that showed up were "untested" (yeah right!), but get this...they were all burned in the EXACT same spot. Seems to me that this is a common problem with these boards. I would just buy some replcements, but I am worried about having to buy another one a week later for the same issue.

All that said...Is there anyway to bypass using these old power supply boards and swap to a switching power supply? Or, if you have two functioning power supplies, quote me a price. It's not my game, so I would have to go back to the owner to see if he's willing to put up the scratch! Thanks!

 

[KenLayton]

Re: convert Pole Position to switching power supply?

www.startechjournal.com has a back issue with the whole conversion instructions to change to a switching power supply.

 

[nocashvalue]

Thanks for the lead Ken, but I was hoping to get some free tips as opposed to paying $20 for a back issue. Do you recommend this publication for other fixes too? Is it really worth the money? I have never heard of it, but could perhaps stand to make the investment if it was truly worthwhile.

Here's hoping I can just find some cheapo power supplies.

 

[KenLayton]

They had a nice several pages write-up of how to convert to a switcher. At the time the article was written the largest available screw terminal power supply was only rated at 12 amps on the 5 volt line. They recommended putting a fan on the power supply to cool it.

Today you could use a 15 amp rated supply and not need the fan.

 

[nocashvalue]

Sounds good Ken. One last question: if I make the change would I need two power supplies (since it originally used two boards) or would the one suffice?

 

[KenLayton]

No, a single 15 amp supply would be fine.

 

[Brentradio]

I have some docs for this on my site here

The main problem with PP is that the 2 game boards are so big and consume so much power that it's hard to get the +5 from the edge connector to the other end of the boards. The ARII boards have what is called a +5 sense circuit that would automatically increase the +5 if it was low. The only problem was that the +5 was fine at the edge connector, but low at the other end so it increased the +5 to get it higher on the other end. This cause too much power on the edge connectors which caused them to burn up. This also caused havoc with the rams and other components on the board which caused lots of other problems. So what to do?

First off rebuild the ARII boards and then do the "sense mod" to disable that "feature".

Here's how to do the sense mod here and here

Then, Tap into the +5 on the harness, and run it to all of the test point tabs on both the cpu and video boards. Do this for all of the ground test point tabs as well.

You can kind of see it here and here

Run a couple of fans inside the cab as well.

This is what I have done.

Or you could just put in a switcher for the +5, but I would still run the wires to all of the test tabs.

You can see my Pole Position Restoration here

 

[shred]

Brent that is some real good advise....

Dave

 

[webdoc90]

Sorry for asking a stupid question but would you still need a fan on the game boards if I ran a 15 amp P/S? I'm considering making this conversion.

They had a nice several pages write-up of how to convert to a switcher. At the time the article was written the largest available screw terminal power supply was only rated at 12 amps on the 5 volt line. They recommended putting a fan on the power supply to cool it.

Today you could use a 15 amp rated supply and not need the fan.

 

[KenLayton]

Yes, you should have a fan blowing on the game boards. They run very hot!

 

[webdoc90]

Thanks. I'll need to construct one of those cardboard tunnels like in this video.

http://www.youtube.com/watch?v=DPtQ4McaR1Q starts at 5:36.

Thanks Ken.