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Sunset Riders Repair

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Share any logs or helpful information you may have to repairs of arcade PCBs, Monitors etc

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  • Sunset Riders Repair

    Sunset Riders
    The first time I powered up the system it was totally dead. No video and the CPU would try to start then halt.

    I removed and checked the main ROMS 18E, 18G, 8E and 8G and was happy to find that they all verified ok, but all of them had bent legs which had missed the socket and folded up underneath the IC. Luckily the legs did not break off when straightening them out and reinserting them into their sockets.

    Unfortunately someone had attempted a repair in the video section and had removed the SRAM and buffers at 11d, 12d, 13d and 14d. When removing those ICs they had damaged a numerous traces. They had attempted to repair the traces, however the repair was unsuccessful.

    I removed all the ICs again and repaired all the traces and installed sockets. I also tested the rams and the buffers and found that one of each of was bad, which was not at all surprising seeing as they were Fujitsu branded, so replaced them.

    With the previous repair now taken care of, I moved to looking at the reason it was not booting. Checking the buffers at 13F and 14F showed data on the inputs but all the output lines were totally dead. Once again, they were Fujitsu, I removed and tested these buffers and they were both dead, so I replaced them and the system booted now booted, coming up with an error on the screen “EEPROM BIT CHECK BAD”

    Click image for larger version  Name:	eeprombitcheckbad.jpg Views:	0 Size:	54.4 KB ID:	2177937

    I checked the serial eeprom at 15B and found that there was no activity so whatever was meant to be reading it was not working. The eeprom is addressed by a 74273 at location 15C. Probing around that chip with the logic probe showed the lines going to the eeprom had no activity.

    I piggy backed the 273 and checked again with the logic probe and this time I had a clock on pin 6 for the eeprom, but other lines were still inactive. So I removed and replaced the Fujitsu 74273 and then system booted past the above error.

    Click image for larger version  Name:	checkingeeprom.jpg Views:	28 Size:	84.9 KB ID:	2177943

    Click image for larger version  Name:	initializecomplete.jpg Views:	0 Size:	77.8 KB ID:	2177936

    Click image for larger version  Name:	testswitchstillon.jpg Views:	0 Size:	92.0 KB ID:	2177938

    But now the next error was the test switch was stuck on. A quick check of the schematic shows that the test switch goes into pin 13 of IC 18C and the data line goes out on pin 12. Probing those lines showed that the input was working fine, but the output had no activity. Time to replace another Fujitsu IC.

    With IC 18C replaced, I turned it on yet again hopeful that I would be greeted with a game, but unfortunately I was only greeted with another fault. At least this time it was the rom ram check screen showing me that the SRAMs at 2G and 3G were bad.

    Click image for larger version  Name:	2g3gbad.jpg Views:	0 Size:	102.7 KB ID:	2177941


    I began probing around those suspected bad SRAMs and found almost no activity whatsoever. Unfortunately the schematic I had did not show these SRAMs so I was unsure where they went. However I had a hunch that the two final buffers at locations 8J and 8K were probably going to be faulty seeing as they were yet again, you guessed it, Fujitsu. So I piggy backed these two ICs and I was greeted with a game screen. I replaced the buffers and turned the system back on and this time, I had no green or blue. It turned out that a number of 7407s at locations 8C, 9C, 10C, 11C and 12C had failed while I had been performing the repair. Not all that surprising given that they are all also Fujitsu. Rather than replacing just the faulty ones, I just replaced all of them which gave me back all the colours.



    Click image for larger version  Name:	blackstripe.jpg Views:	0 Size:	117.7 KB ID:	2177939
    Click image for larger version  Name:	blackstripe2.jpg Views:	0 Size:	117.8 KB ID:	2177940



    Now I was very happy to be looking at the game, though there is still a few faults to find. As the above images show there is parts of the image missing on certain screens (ignore the line through the middle of the picture, that is my faulty test monitor) and I also have more faulty buttons, but unfortunately I do not have any of the required 74253 ICs to replace them. So while I can get into the test menu and go up and down, I am unable to enter any of the test options by pressing the start button. So the final few faults will have to wait until I order some more ICs from Digi-Key or Mouser.
    Attached Files
    Last edited by cwispy; 23 November 2020, 10:10 AM. Reason: Typo's
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    Reproduction Circuit Boards
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