Primal Rage arcade (Help needed)

[Eruption2405]

Hi everyone, im new here but I'm desperate for some help.

My oldest son is going off to Uni, and we decide on a project before he went off and brought a Primal Rage arcade.

We have got alot of thing working so it now turns on properly, I.e monitor and lights but once it begins to boot we are greeted with a scrabbled screen (aatached photo 1). If we press button 3 (top left button) we get a beep and then a screen with work ram bad on it (attached photo 2).

We have been over the board and cant see and visual issues. We've looked though the operators maunal and cant find any answers to try fix the problem.
Ive had a multi meter on it and the both the 5v and 12v lines are there and stable. Ive looked on the Internet for hours and days but can find anyone with the same problem either.

Can anyone give us some tips, advice or anything to try resort this arcade to even boot up to test the roms properly. Im desperate to make some progess before he leaves in just over a months time if possible.

Thank you for your time reading the post.

 

[xga]

Sounds like you might have a fault with one of the SRAM's used for the work RAM which I think might be located at 21K and 21M/N on the main CPU board. They should be socketed, so they are nice and easy to remove. Hopefully you have the means to test them. If not, you could try swapping them with the SRAM's from locations 12H and 16H and see if the behaviour / error message changes.

It might also be worth seeing if the board is well enough to enter into the service mode so that you can conduct various RAM and ROM tests from there.

 

[Eruption2405]

Sounds like you might have a fault with one of the SRAM's used for the work RAM which I think might be located at 21K and 21M/N on the main CPU board. They should be socketed, so they are nice and easy to remove. Hopefully you have the means to test them. If not, you could try swapping them with the SRAM's from locations 12H and 16H and see if the behaviour / error message changes.

It might also be worth seeing if the board is well enough to enter into the service mode so that you can conduct various RAM and ROM tests from there.

Thank you for the reply, i do appreciate any help.
I dont have a way to test them, what would I need to test them?

We have just tried to change the chips over as you suggested and now get a new screen but no error code, no matter what we touch though the colour will change to green and then some artifacts appear at times too.

 

[Eruption2405]

We've just put the chips back to the original orientation and not get both, work ram bad then cycles to color ram bad

 

[Eruption2405]

We tried some different placements of those 4 chips and get video bad ram

 

[xga]

So it sounds like some of the RAM IC's might be faulty otherwise if it was a TTL logic issue, the error message would have stayed the same when you swapped the RAM over. Most EPROM programmers will be able to test RAM IC's, so if you know of someone who has one, you might be able to get them to test it for you. Or there are devices you can buy like the Retro Chip Tester that can test a multitude of IC's.

If you're not able to test them, then it might be worth the gamble of purchasing a few replacement 62256 SRAM's and swapping them over. You will need to get them in the DIP28-300mil (narrow) package. You can see compatible options on this page: https://www.citylan.it/index.php/SRAM_32k_x_8

Something like the CY7C199 in DIP28-300mil are a good option.

 

[Eruption2405]

So it sounds like some of the RAM IC's might be faulty otherwise if it was a TTL logic issue, the error message would have stayed the same when you swapped the RAM over. Most EPROM programmers will be able to test RAM IC's, so if you know of someone who has one, you might be able to get them to test it for you. Or there are devices you can buy like the Retro Chip Tester that can test a multitude of IC's.

If you're not able to test them, then it might be worth the gamble of purchasing a few replacement 62256 SRAM's and swapping them over. You will need to get them in the DIP28-300mil (narrow) package. You can see compatible options on this page: https://www.citylan.it/index.php/SRAM_32k_x_8

Something like the CY7C199 in DIP28-300mil are a good option.

Thank you xga, im gonna order some replacement ram chips and see what happens. Ill also see about getting anEPROM programmer if i can find one cheap enough too. I'll keep you updated.

 

[Eruption2405]

Brought an eprom programmer but I cant get it to work, not sure if they are different types and ive got the wrong one. Any ideas?

 

[xga]

I've never used or seen that EPROM programmer before, so I can't tell you exactly what to do.

Did it come with a manual or any software? If not, I think the manual, USB driver and software installer linked below should be compatible. From a quick glance at the manual it looks like the programmer is able to check RAM IC's, so you should be OK.

The manual is here: https://www.rhydolabz.com/documents/27/SP200S USER GUIDE.pdf

The USB driver is here: https://www.rhydolabz.com/documents/27/USB TO SERIAL DRIVER.zip

The software installer is here: https://www.rhydolabz.com/documents/27/WLPRO_V220_SETUP.zip

Once the software is installed, you will want to change the language of it to English as it will most likely default to Chinese, then select the device you want to test (the model of RAM IC). Be careful and pay attention to how you orient the particular IC into the programmer (hopefully the software displays a picture when you select the device) otherwise you could damage the IC.

 

[Eruption2405]

Once again, thank you for your reply Xga, i have done done that but I am unsure how to see the model of the RAM ic as it doesnt seem to have mosel or even ms62256h-20nc (thats the writing on the ram chip) on the list i can pick. Am i doing something wrong?

 

[xga]

Apologies, Eruption2405. I was looking at the screenshot in the user manual of page 5 and saw that it listed SRAM / DRAM in the type of devices you could choose, so thought it would be compatible. After looking at the supported device list https://www.matni.co/Arabic/Programmer/SP200SE/SP200SE.htm this is a programmer that is limited to programming devices like MCU's and serial EEPROM's and cannot test RAM's.

A popular programmer for beginners that is compatible with nearly 20,000 devices (http://www.xgecu.com/MiniPro/TL866II_List.txt) is the TL866ii Plus. These can be purchased for around GBP 40 / AUD $100. With the MiniPro software for the TL866ii Plus, you would simply select 62256 from the device list and then you would be able to test your RAM IC's.

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[Eruption2405]

That would make sense why I couldn't get it to work. I'll wait for these ic ram chips to arrive and test it with them then if no progress ill order one. I do appreciate your help