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Pole position 2 repair


cal2

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Hello,

 

I am helping a friend to repair a pole position 2 pcb. Here are some pictures of the problem:

 

http://img150.imageshack.us/img150/6650/40408724.jpg

 

This is the atari version, not the namco. Looking at the manual, it says that RAM 2 indicates a bad ram chip at 8H on the video pcb.

 

More news when I have more details ;)

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Hello,

 

I am helping a friend to repair a pole position 2 pcb. Here are some pictures of the problem:

 

This is the atari version, not the namco. Looking at the manual, it says that RAM 2 indicates a bad ram chip at 8H on the video pcb.

 

More news when I have more details ;)

 

I'm sure this is what the graphics used to look like when we'd have a few beers! :lol Hope you get her going. Have a Namco PP cab myself, very basic game but fun to play (still!). :D

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Hello,

 

I am helping a friend to repair a pole position 2 pcb. Here are some pictures of the problem:

 

http://img150.imageshack.us/img150/6650/40408724.jpg

 

This is the atari version, not the namco. Looking at the manual, it says that RAM 2 indicates a bad ram chip at 8H on the video pcb.

 

More news when I have more details ;)

 

You should never buy games Cheap once owned by Stevie Wonder:lol

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haven't tracked it down yet, but haven't had much time at all, got my rig set up again to fix a few up i need to get going again, so hopefully when all the refinance has died down, i'l take a couple of weeks off to do that sort of stuff

Have time to myself :)

 

Could be a simple ram swap on this, or be a pita to track down. Put about 80 hours into a few sets so far with no great progress.

Need to make a ring up to see all the busses at once.

 

Any takers on a big track job for a pcb etch? Know what i need, just need someone with pcb knowledge for help. Would be single sided with wire jumpers being a 1 off, but not anything major

 

For the old farts, a front buss panel like the before home computer time :D

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not hard, only needs +5v and gnd, heaps of current draw, power hungry beast , so make them thick and plentiful for the power. Some need 2 switches to start up

 

Then connect the rgb to it and away you go, forgot about the sound till later, thats another headache

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Yep, I will be wiring only the necessary to have a display. I am not worrying about the power supply since I am using a 650W atx power supply ;)

 

not hard, only needs +5v and gnd, heaps of current draw, power hungry beast , so make them thick and plentiful for the power. Some need 2 switches to start up

 

Then connect the rgb to it and away you go, forgot about the sound till later, thats another headache

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Hello,

 

I have wired only the necessary to get a picture :

 

http://img7.imageshack.us/img7/4879/1000514a.jpg

 

The jamma header is getting hot fast. Is it normal ?

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Hello,

 

I have wired only the necessary to get a picture :

 

http://img7.imageshack.us/img7/4879/1000514a.jpg

 

The jamma header is getting hot fast. Is it normal ?

 

No.

 

However if those thin red wires are all you are using to supply power, you might want to triple them up as there is no way they could handle the current necessay - and may be the cause of the heat...

 

Cheers

Jacob

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Some progress ! I replaced the 2149 1kx4 ram @ 8H by an equivalent 2114, and the game booted ! It passes all self tests, but keeps reseting before attract mode...Maybe a power supply issue since I have not doubled / trippled / etc the 5V rails..
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I have rewired the +5V and GND with bigger wires. Unfortunately, this makes no difference.

 

I changed the Z80 cpu by a known working, but this changed nothing, so I assume the Z80 is good.

 

I cannot test the 2xZ8002 yet since I have no parts for it yet.

 

Comparing the boot of the game to mame, I found that no sprites are displaying.

 

So I dumped the eproms related to 32x32 sprites:

 

136014.119

136014.166

136014.168

136014.175

136014.120

136014.167

136014.169

136014.174

 

These are 2764 eproms. I didn't have the time to check if they are good, but I have tested the game without these eproms and it mades no difference. So I assume that the sprite generation circuit may have a fault.

 

I am going to dump all eproms and check if they are working in mame to know if they are good or not.

 

More new soon ;)

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Something strange happened when I was dumping the eproms. I dumped the boot code and it returns all 0. However the boot eprom was working on the pcb since I wouldn't have the test mode otherwise. Now, when I put it back, it doesn't boot anymore.

 

Any idea how the eprom could be dead after simply reading it ?

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I have programmed a 27C512 in replacement of the 2764 and it works again and now I am sure this eprom is good.

 

Self test is 100% ok (ram, rom, controls), however, the pcb suffers from a low +5V.

 

I measured it at 4.6 volt. That might explain why it resets early in the game. However, I have no means to higher the voltage since I am using an atx power supply.

 

Also I am surprised that the atx power supply doesn't perform as well as I thought.

 

Is it normal ?

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I was able to adjust the 5V so it doesn't run anymore @ 4.4 V. However this changes nothing. The game reboots just at the beginning of the attract mode.

If I push coin + start buttons fast enough I can see the circuit selection, but it reboots.

 

RAM and ROM are detected OK in the test mode. I have wired most controls but since I don't have the original cab to test it in...

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The game now reboots just after the self test grid. Rom and ram checks are still ok.

 

The /reset line is always high on the z80. The two z8002 are reseted when the game resets after the self test grid.

 

Swapping both z8002 changes nothing

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is it an original board? there are a lot of custom Namco chips used on that game. From memory one of them controls the master clocks/reset. There's also a microcontroller for I/O and protection (similar type to Galaga that I decapped and extracted a couple of years back). Lots of nasty custom chips. You need to treat it like Galaga, only 2X bigger.
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I have found usefull information about the graphic problems of the pcb using modification to the pole position 2 driver in mame:

 

- sprites don't display at all

- one part of the tilemaps (alpha) don't display correctly

- the palette PROM or the 128V input is bad, so the colors ar wrong.

 

Here is the screenshot of mame with these modifications:

 

http://img11.imageshack.us/img11/8618/polepos2a1.jpg

 

It matches what I get with the pcb.

 

A way to reproduce the reset at the beginning of the attract mode is to disable watchdog reset. However, should the watchdog pulse the reset line or is there an other way to do it ? I don't remember having seen a reset pulse, but since it happens quickly, it may be difficult to see it

 

The watchdog is handled by a 4 bit binary counter 74LS161 @ 6A which is clocked by the 128V signal. The initial value is 0. When there is a carry, the carry is outputed to the reset circuit to reset the Z80.

 

The binary counter is reloaded by a pin called "P,R230" which I don't know yet where it comes from. It should be mapped in cpu space or one custom IC connected to cpu space, but I haven't found it on the schematics yet.

 

Also, the 74LS161 is near the battery and all components near the backup battery seem to have suffered from corrosion.

 

I think I can try to disable the watchdog to see if it changes anything first...

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