Toki Seibu Arcade Repair. No Video / Missing Sprites With Glitches

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    • Toki Seibu Arcade Repair. No Video / Missing Sprites With Glitches

      Board: Toki
      Symptoms: No video/ Corrupt and Missing Graphic Sprites.
      Repairer: lukemorse1

      There were a couple of things wrong with this board so Ive decided to combine them into a single post.

      Asking around to people like Caius as well as doing some research on the internet I found out that there really isnt a whole lot of info out there on Toki so I thought I would add a little more. Although I did come across a couple of good repair links for the board regarding graphic issues and sound trouble neither were similar to the problem I was having with this board so I decided to give it a go on my own.

      First inspection of the board shows a busted UEC-51 RGB DAC which is responsible for video display. I ordered a replacement from Caius which arrived quickly and just what the board needed.

      Due to these chips being snapped off due to standing vertically I decided to bend a row of header pins on a 45 degree angle as well as the pins on the replacement rgb dac from Caius in order to make it lay more flat and not snap off again.

      Once the chip was installed, the board showed life.

      The first dipswitch menu showed up clearly without any glitches or problems which was promising but after hitting start, it was apparent that everything wasnt ok.

      As the title started up, the wizard on the right had wavy lines in it as well as the hand and Toki had vertical lines going through him. Even in demo mode as well as actual game play there were thick lines going through the graphics and enemy sprites were sometimes completely missing until you got close. By that time you were already dead so it was impossible to play. See pictures below.

      I contacted Caius on here as he had a lot of experience with this board and mentioned reflow of the surface mounted ICs. Looking at these custom ICs you can see that there are several legs that are tied together and some that are difficult to see but as for the pinouts on them I have no clue as they are custom. There pins that are tied together have some similarities with neighboring chips but also have different pins combined with globs of solder which makes it confusing to tell if someone had dropped a bit of solder or if it was from the factory.
      Lifting a couple of the legs showed the pads under were actually connected. I made sure to take pictures of each chip before reflow as not knowing what pins were originally tied together and then accidentally bridging a couple pins could be a pain to track down later.

      After reflowing the 931451A chips I didnt notice a thing. As I moved over to the board however I started to make some progress.
      On the opposite side of the JAMMA harness on the far left side there are 4 surface mounted dacs numbered 942051B.
      After trying to do some reflow on the bottom right chip first I powered up the board only to find that the graphics had gotten worse. I knew at this point that these were the chips responsible for the sprites. Going over the same chip again and double checking for bridges, the graphics returned to the glitched out state they were before.

      As I was going over each of the chips I found that sometimes I would get worse results but never better ones. I decided to pull out my probe and check the 74ls273s. I first checked the one located next to the resistor array at point 13 on the board and found that all pins were high. I decided to piggyback a good 273 onto it without any change. I then cut the power to the chip by cutting the VCC pin to see if it had any effect and turned the power on again. This time, all the characters were blocks but you could still see the lines like before so this chip didnt show much promise.

      I then turned to the smae 74ls273 above it and checked the pins to find that all of them were low. After using my continuity meter I was able to see that there were several traces running from that chip to the 942051B dac above it. piggybacking this one caused all kinds of once missing graphics to suddenly pop up. Thinking I was on to something I removed the chip and put in a socket. I decided to test it without the chip in and I could clearly see that all of the sprites were now clear, even the enemy sprites looked great although there were still some strange graphic glitches above the characters they were point values or meat or something similar.

      After replacing the chip with a new one and rebooting the game, all graphics were present without any glitches.

      Verdict, I really dont know about the pinouts on these custom chips but if you are having graphic issues I would recommend looking to the 74ls273s as well as the 94201B dacs.

      As a final note. These Toki boards have the top outer boarder around the board with a - negative rail around the side and the bottom has a +5v edge all around it. This board had some older pcb feet on them and one of the plastic feet had snapped off. The metal part of the bottom of the foot and the top part of the screw head made contact with each other (previous owner) which caused the board to burn on the edge.

      If you are going to use pcb feet on this board, I recommend using plastic washers between both sides in order to avoid it sparking and burning. see pictures below.

      Hopefully this will help others who may be experiencing difficulty.
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