Old Rom Chips Need Replacing

[Goatz18]

I have an Atari LeMans cabinet and two boards for it. Both don't work. I removed the ROM chips of both to clean the severe visible oxidation on the legs to find several with very brittle/bent/broken legs. I need some new ones, so here goes my new to the hobby question: Can new ones be purchased, from someone who can program blank chips, or are they irreplaceable? 35 years have not treated them very well and I can not imagine that new ones can't be produced to keep this game kicking. Am I better off finding a new functioning board entirely? Any help or suggestions would be much appreciated, thanks.

I do not even have a LeMans rom set in my MAME roms. That would mean not just anyone could do this. I would need someone with functioning LeMans ROM chips who would have to extract their contents to new chips, if it is at all possible. That is at least what I have deduced so far.

 

[Goatz18]

I have been told that the rom chips for LeMans that I am talking about are in fact Atari 2k MOS PROM chips. I was also told that there is no known direct eprom or other chip that could replace them. But that a separate circuit board containing 2716 eproms could be made and plugged into the rom sockets to take the place of the prom. Is this my only option to replace the Atari prom chips?

 

[Arcadenut]

I have an Atari LeMans cabinet and two boards for it. Both don't work. I removed the ROM chips of both to clean the severe visible oxidation on the legs to find several with very brittle/bent/broken legs. I need some new ones, so here goes my new to the hobby question: Can new ones be purchased, from someone who can program blank chips, or are they irreplaceable? 35 years have not treated them very well and I can not imagine that new ones can't be produced to keep this game kicking. Am I better off finding a new functioning board entirely? Any help or suggestions would be much appreciated, thanks.

I do not even have a LeMans rom set in my MAME roms. That would mean not just anyone could do this. I would need someone with functioning LeMans ROM chips who would have to extract their contents to new chips, if it is at all possible. That is at least what I have deduced so far.

If the PROM itself is not bad, but you just have broken legs, it can be saved.

You need a socket, and maybe a Dremell.

Here is what I had to do to a Dig Dug Custom to save it..

The legs had broken off flush with the case, so I had to Dremell the case down until I could see the traces internally. Each leg that broke off, I put in a piece of solid wire (clipped ends from Caps) and soldered it to what was left of the pin.

In the case of the above chip, I had to solder it to the trace inside the chip itself.

If the PROM is bad (beyond the legs), then you'll need to try to find a replacement, which is difficult these days. Took me months to find a replacement for the Atari System 1 boards and they are not cheap.

What is the Part Number of the chip that is broken?

 

[channelmanic]

I have a slew of old Atari PROMs... the older bigger chips... that I haven't listed anywhere yet. I may have some NOS ones of what you need.

 

[Goatz18]

Ok so out of the 6 chips I have, on two of the chips the small end of a single leg broke off, the fat part is still there, and on one other two legs broke. They all have good connections to the fat part of the legs. What you are saying is that I could solder a wire to those exposed fat leg parts and connect them to the PCB. I have seen "jumping" PCB connections with wires but didn't think to apply the same concept to a chip leg. That definitely sounds like what I might do. Thanks Arcadenut.

The numbers that are in the schematics are 005837-01, 005838-01, 005839-01. On the chips they are marked with just 5837, 5838, 5839. I would love some spare ones even if I get these repaired and running so channelmanic feel free to look for some, I'll definitely take 'em if you got 'em. On one of my 5837's oddly is marked with 'SN 74186,' and 'a 7445A' instead of 5837 like the other(s). Not sure if that is just a universal Atari chip that can be interchanged or if it is wrong. Thanks.

 

[Arcadenut]

Ok so out of the 6 chips I have, on two of the chips the small end of a single leg broke off, the fat part is still there, and on one other two legs broke. They all have good connections to the fat part of the legs. What you are saying is that I could solder a wire to those exposed fat leg parts and connect them to the PCB. I have seen "jumping" PCB connections with wires but didn't think to apply the same concept to a chip leg. That definitely sounds like what I might do. Thanks Arcadenut.

Actually, what I am saying is, put that chip in a socket, and then solder the leg to the socket. I'll see if I have a pic, if not I'll take one.

No reason to solder to the board directly.

 

[KevinMullins]

on two of the chips the small end of a single leg broke off, the fat part is still there, and on one other two legs broke. They all have good connections to the fat part of the legs.

I take clipped off legs from a junk chip and solder the new leg directly to that fat part that is still there. CLip the donor leg close enough to the case to get all of the fat part of the new leg. Just clean what is left on the old chip well, tin it with a smidge of solder, position the new leg, heat it. So solder fat part to fat part....walla, new leg.

 

[Goatz18]

Actually, what I am saying is, put that chip in a socket, and then solder the leg to the socket. I'll see if I have a pic, if not I'll take one.

No reason to solder to the board directly.

Ah, that works a little better. A pic would be fantastic.

I take clipped off legs from a junk chip and solder the new leg directly to that fat part that is still there. CLip the donor leg close enough to the case to get all of the fat part of the new leg. Just clean what is left on the old chip well, tin it with a smidge of solder, position the new leg, heat it. So solder fat part to fat part....walla, new leg.

Now that is brilliant. As long as the fat part is still there just overlay a new leg to it via solder. I don't have junk chips but I imagine just buying any IC from Radioshack with similar sized legs would work.

Thanks for all the great answers, I definitely wouldn't have thought of all this stuff.

 

[Arcadenut]

Ok, here is a shot of the Repaired chip. The other legs are bad looking as I'm trying to find a good way to clean them without breaking them off. The legs are very fragile.

 

[electrotim]

Ok so out of the 6 chips I have, on two of the chips the small end of a single leg broke off, the fat part is still there, and on one other two legs broke. They all have good connections to the fat part of the legs. What you are saying is that I could solder a wire to those exposed fat leg parts and connect them to the PCB. I have seen "jumping" PCB connections with wires but didn't think to apply the same concept to a chip leg. That definitely sounds like what I might do. Thanks Arcadenut.

The numbers that are in the schematics are 005837-01, 005838-01, 005839-01. On the chips they are marked with just 5837, 5838, 5839. I would love some spare ones even if I get these repaired and running so channelmanic feel free to look for some, I'll definitely take 'em if you got 'em. On one of my 5837's oddly is marked with 'SN 74186,' and 'a 7445A' instead of 5837 like the other(s). Not sure if that is just a universal Atari chip that can be interchanged or if it is wrong. Thanks.

The SN74186 chip is a 64 x 8 PROM. It will not work with this board, pinouts do not match.
The 005837-01 is a 2048 x 8 ROM.
Both chips have 24 pins so they look the same.

 

[dgersic]

I do not even have a LeMans rom set in my MAME roms. That would mean not just anyone could do this. I would need someone with functioning LeMans ROM chips who would have to extract their contents to new chips, if it is at all possible. That is at least what I have deduced so far.

If your ROMs are still good (unknown) despite their physical problems, it may be worthwhile to find somebody who can dump them to images for you. Then a new set could potentially be programed (aka "burned") from the images.

 

[dgersic]

I have been told that the rom chips for LeMans that I am talking about are in fact Atari 2k MOS PROM chips. I was also told that there is no known direct eprom or other chip that could replace them.

Because there are no direct replacements, you have a bit of a challenge on your hands, but a surmountable one. If you can get the images from these, or from somebody with a working set if yours are bad, then the rest is relatively easy.

But that a separate circuit board containing 2716 eproms could be made and plugged into the rom sockets to take the place of the prom. Is this my only option to replace the Atari prom chips?

Well, if you can't find a good set of originals, building an adapter is another way to fix this. I had to do this once for a 74S288 PROM that I couldn't replace. I built this 2716 adapter from perf board and wire. Worked fine. If I'd had more time, I would have etched a board instead of the wire wrap, but the game was heading to a show, and the owner had already sold it for delivery right after the show, so it wasn't going to be in my shop for long.

 

[Goatz18]

The SN74186 chip is a 64 x 8 PROM. It will not work with this board, pinouts do not match.
The 005837-01 is a 2048 x 8 ROM.
Both chips have 24 pins so they look the same.

Aha. The roms that came on the PCB in the cabinet are all correct. Of course that chip was on an "untested" board that I purchased. Thank you for the information, that actually helps a lot and I'll tell you why. The PCB that came with the cab powered up and the game started to run but was unplayable and went through a weird cycle on the screen. I took the roms off of this board and replaced them with the roms from the "untested" board and I got the same thing, the game powered up and had the same weird cycle on the screen. Now I deduce that something had to be wrong with the good 5837 chip, bad connection or any number of things, but somehow allowed the game to still play, albeit incorrectly. That is the only way to explain how an improper SN74186 chip could have the same effect on the gameplay. Right? Or am I missing something?

Of course the proper 5837 had a seriously brittle/fractured leg that had no chance of staying on if I were to push it in the IC socket one more time, and it did indeed break off. Whether or not that could have caused the problem with it in the first place, I don't know.

Because there are no direct replacements, you have a bit of a challenge on your hands, but a surmountable one. If you can get the images from these, or from somebody with a working set if yours are bad, then the rest is relatively easy.



Well, if you can't find a good set of originals, building an adapter is another way to fix this. I had to do this once for a 74S288 PROM that I couldn't replace. I built this 2716 adapter from perf board and wire. Worked fine. If I'd had more time, I would have etched a board instead of the wire wrap, but the game was heading to a show, and the owner had already sold it for delivery right after the show, so it wasn't going to be in my shop for long.

I have been offered by someone that as long as the fat part of the legs are still attached, which they are, they could make images of the chips for me. And thank you for the picture and your adaptor experience.

To clarify, if I did get the roms images, put them on 2716 eproms, attached the eproms to an adaptor and attached that to the game PCB, all should be well? I also ask, how would the adaptor be jacked into the game PCB? I imagine there is a smaller IC socket of some type on the other side of your adaptor that would go to the IC socket on the game PCB?

 

[steph]

To clarify, if I did get the roms images, put them on 2716 eproms, attached the eproms to an adaptor and attached that to the game PCB, all should be well?

Technically, yes, that should work.

The only caveat is that eproms of that era
had considerably slower read-access speeds than proms.
(ie. they were "slower" )

This is not always an issue, but I've seen instances of where this was a problem
(..notably on the Williams decoder proms being replaced by eproms )


Steph

 

[Goatz18]

Technically, yes, that should work.

The only caveat is that eproms of that era
had considerably slower read-access speeds than proms.
(ie. they were "slower" )

This is not always an issue, but I've seen instances of where this was a problem
(..notably on the Williams decoder proms being replaced by eproms )


Steph

Ok good to know. Thanks.

I do have one more question. Is there a MAME set of the Atari Lemans roms? Could one be made from extracting these chips?

 

[electrotim]

Ok good to know. Thanks.

I do have one more question. Is there a MAME set of the Atari Lemans roms? Could one be made from extracting these chips?

Yes, you can read the roms but without a working board or a known good set of roms.
You won't know if the contents are correct.

Even if you read the roms they still won't work in MAME. The MAME folks would have to write
a driver for the game.

These ROMS are not your normal everyday roms. They have some extra functions and a
different pin out. +5volts, -12 Volts. You can't use just an adapter that reroutes all of the address
and data lines.

 

[electrotim]

PS.

Most do not realize that this board does not use a CPU.
It has no microprocessor.

 

[Stiletto]

In case this comes up AGAIN, here is the preliminary datasheet for the Atari Le Mans PROM.

It's been identified through past Internet research as a Mostek MK28000 PROM (the same as in Tank / Tank II.)
313K mk28000p.pdf - http://www.sendspace.com/file/36nkqm

Also here are the databooks which contain it.
http://bitsavers.trailing-edge.com/pdf/mostek/_dataBooks/1977_Mostek_Memory_Products.pdf - 06-Aug-2013 14:47 17M
http://bitsavers.trailing-edge.com/...stek_Memory_Data_Book_and_Designers_Guide.pdf - 06-Aug-2013 18:07 38M

That still doesn't exactly help, building a dumping rig for this is not trivial.

Apologies for the bump but I happened to come across it and thought I'd post something relevant to the discussion.