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Sega Blast Cities


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  • Sega Blast Cities

    Here I am with another project - I'm a sucker for punishment!

    A few weeks ago, I was given an ad on Gumtree for a couple of Blast Cities located in Newcastle. I was umming and ahhing about getting them as I really don't have room. Mrs said, "just buy and fix them up, then decide what you want to do, keep both, keep one and sell another cab in your garage, or sell both, you know you love to bring things back fro the dead". Soon after I msg'd the seller to pick up the coming weekend.

    Unfortunately I didn't have a vehicle to transport it, so I asked a mate to use his car and off to the local 7-Eleven we went to hire out a trailer.

    The ad for the Blast Cities were NOT WORKING, and of course, there's nothing more I love than bringing cabs back from the dead - all dependent on Joey. If Joey can bring them back, great, if not, I'll sell for what it cost me to get to my house. Here they are loaded up

    Lucky for me, the seller decided to give me a whole bunch of chassis and I took the opportunity to grab whatever he would give me. In the end I got 2x MS2931 and 3x MS2930 (2 of which were in side the cab) and a Wei-Ya chassis that I was advised was a drop in

    After the drive home, I left it as it was and started sussing out what I was in for the following day..

    One cab appears to be worst for wear than the other, multiple areas have paint flaking off - I am not repainting these cabs, they are just too much work, so I will embrace the war wounds.

    Never worked on a Blast City before, I had no idea what was what and this spaghetti of wires was quite intimidating, I had a trusty multi-meter, but fortunately, the other cab was quite intact

    After a solid hour of detangling wires and putting some cable ties, I ended up with something a little more respectable. This cab unfortunately is missing a JAMMA loom.

    Decided, I'll give it a good clean once I have everything working.

    I reached out to Joey and he advised that he wouldn't touch any chassis that had black goop. Of the 5 chassis I got, only 2x were black goop free (a 2931 and a 2930).

    Removed the monitors out of the cab - WHAT A PITA IT WAS!! Compared to other cabs I've worked on, the Blast City is by far the most painful cab to get the monitor out.

    Eventually got them on the floor

    It was a shame that both tubes had some burn in with one monitor having worse burn in than the other.

    Now the monitor was out, I quickly ran some test to see what the go was with them and one had no image, just a blue screen.

    Off to Joey they went.

  • #2
    Joey advised that he worked on both chassis and was able to bring them back to life so they were operational. He also stated that he used the last 2931 flyback he had so that was a bonus.

    They arrived and looked brand new compared to what they were when they were sent to him.



    I couldn't decide which chassis to test first, so I decided to go the 2931. As soon as I connected it, I was in awe of the picture quality - but something was "off". After trying to adjust the display, the best image I could get wasn't a full screen image, it appears to have been zoomed in by about 20%

    I reached out to Joey and he asked me to try and make adjustments on the B+ pot

    As you can see in the video, the image slightly adjusted - but nowhere near enough of what I am expecting.

    So I decided to work on the other chassis, the 2930.

    Connected it all up, and upon turning on, I got background image, but I couldn't get any red or green on the image and no amount of turning the gain pots changed the image.

    By this point, I was extremely frustrated with both chassis and I've always heard how much of a PITA they were. Reached out to Joey again and he said to check the neck board for some loose transistors, they seemed fine, so the only thing I could really do was to send the chassis back to Joey for further inspection.

    I was ready to cut my loses and call it a day......

    But me being me, I am quit stubborn and I don't like to wave the white flag so easily so I thought I'd do some trawling on the interwebs

    After reading numerous threads, I believe I came to the conclusion that the flyback being used on the 2931 is not an original nanao. Whilst new, it wasn't a complete 1:1 and it seemed to point to that direction. So I decided to try my luck and roll the dice.

    The plan was to do some electronic surgery remove the flyback from the dead 2931 and put it on the newly refurbished one to "test" the theory! Never worked on CRT's before at this level, I was packing s**t!

    10 minutes worth of desoldering, I was able to get the flyback off both 2931's. I was a little weary about the flyback as there appears to be a break on the anode cable.

    I still went to test - curiosity got the better of me.

    After installing the flyback and the chassis back to the monitor, I turned it on - expecting arcing, or a loud hum, noise.. I was greeted with the following image

    WINNER! so I thought!

    The original flyback clearly shows the image is much smaller than the other flyback I had. I started adjusting the image, and then a few funny things started happening which got me scared so I turned it off.

    Check it out from 47 seconds...

    Called it a night as I was a little too scared

    The following day, I spent some time reading through more threads and with the help of djcalle, he pretty much confirmed that the MS2931 and MS2930 share the same flyback. I have 2x dead MS2930's but may have working flybacks.

    So I decided to once again desolder the flyback. Nice and clean!

    Flyback cleaned and dusted - it was at this point I realised why some monitors may potentially die. All the black goop appears to have gone on a pin on a flyback and I couldn't get any form of continuity from the pin to the top where the black goop was.

    Installed the flyback and kept everything crossed and hoped that nothing exploded on me when I put the power on.....

    Voila! Perfect 15khz full screen image!!

    I let the game run on for a lot longer and I got 30 minutes without any funny zooming in or anything like in the previous video

    Big massive win for the 2931. Next up tackle the 2930.


    • #3
      Bloody hell man, awesome work!


      • #4
        So this post will be about the 2930!

        As mentioned in the previous post, when I plugged in the 2930 all I got was a blue image, I couldn't get any Red or Green bias dialled in. When I reached out to Joey who said check the transistors which I did and couldn't find anything obvious. Rather than sending it back to Joey, I thought, I'd try my luck with changing the neck board with the other two spare 2930's.

        Simple enough mod, desolder two wires from the flyback and unplug a couple JST connectors.

        When I fired her up, I was greeted with a red and green! Of course there's no blue!!

        So I tried my luck with the third and final neck board....


        Whacked on a game and she came out all good, obviously needed to dial in the horiztonal/vertical size and positions.

        So 15khz is now running perfectly, I thought I'd try my luck with getting 31khz...

        First attempt at using a DC didn't go down too well.

        As you can the image is waaay too narrow and my horizontal pot was already maxed out.

        Reached out to a few people I knew that had the blast city and a 2930 who don't seem to have this issue. So I had to trawl the interwebs further

        I found a jumper on the chassis that stated "narrow" and "wide", so I tried swapping it around

        That didn't work. I then tried the 2931 to see if it was experiencing the same issue with 31khz, no such issue as I was able to adjust accordingly.

        I then read a post on Arcade otaku about changing a horiztonal limit. After looking for about 5 minutes on the board, I tried changing "H.S.L" and saw it improve so I maxed it out to get full screen. I later found out this pot stood for Horizontal Size Limit

        Working perfectly with a Naomi! Look at that buttery image!

        Monitors are now working, so it's time to work on the cab itself, test for power and what not as they haven't been tested at all yet.


        • #5
          Now I sorted out the monitors, it was time to start making my way onto the cab and seeing what else needs to be fixed.

          First off the rank was power. I needed to figure out what was the status of the power.

          This cab is 100v, so I purchased an external step down transformer from ebay as my test rig. I have plans to do internal step down at a later point in time (if I can be bothered )

          Plugged the psu into its respective spots in the I/O, plugged the JAMMA harness with a pandora's box as a test pcb... flicked it on and... nothing! No fan, no light, no sound, nothing! Boo!

          Went over the cab again, made sure the "kill switch" at the door was pressed (even made the adapter for the kill switch), checked and replaced the fuse on the psu, still nothing.

          Made sure 110v was coming out of the step down - check!

          Unfortunately, I couldn't find the reason it wouldn't power on. I gave up for the night

          The following day, I was advised to check the Blast I/O if it was getting 100v, since everything has to go through the I/O before it can be fed back to the PSU. I started pronging around to find the 100v line and I eventually found where the 100v was and realised - wtf? It went nowhere!

          So I did what everybody should always do first - RTFM!

          I found exactly what that connector did when I read the f***ing manual

          It's clear in the manual, there's a connector to loop back the 100v, so I made the little connector.

          The moment I connected that, things started to work as expected

          After getting power to the cabinet, I tested the voltage of 3.3v, 5.0v and 12v. Both 3.3 and 5v needed to be dialed back but I didn't realise the 12v didn't have an adjustment pot on the blast!

          5v right on 5.00

          3.3v right on 3.3v

          12v is slightly under - hope this doesn't cause issues.

          The last thing to check are the speakers - I've heard a lot of issue with the blast speakers, especially the challenges involved when you have to find a replacement.

          I'm lucky to say both speakers appear to work - I haven't bothered taken them out as I don't really want to split the whole cabinet in half to get to the speakers.


          • #6
            Since the first cab is now confirmed operational, this cab seemed to be the better condition cab so I gave it a good clean!

            It's amazing what some elbow grease and a magic eraser can do! I personally like some "war wounds" on the cab so I decided to keep this particular cab as my shmups cab

            Some before shots

            Some after shots

            Once all the dirt, grime and stains were gone, I spent a decent time on hand cutting and polishing the cab using some septone fibreglass boatcare products

            After all completed, she's looking clean and shiny!

            The control panel has come good too

            Will start installing the monitor and parts back into place


            • #7
              I hit a snag the other night

              I started cleaning the second cab and as I gave it a good wipe down, the paint just started flaking off, and it go worse and worse as I cleaned more..

              The initial thoughts were "touch up" but what started like this...

              Ended up like this after some elbow grease

              Some flaking...

              After a wipe down it looked like this - so I just started sanding

              And then I decided, there's no way I could "touch" this up without a proper colour match, so for those that remember my Naomi Universal project and me saying in the first post " I am not repainting these cabs, they are just too much work, so I will embrace the war wounds", it looks like I'll be painting this mofo

              I'll keep this cab and get rid of the other "better" condition cab - I really am hating this cab of all the cabs I've worked on lol

              An hour later, the cab is officially stripped out! (took me an hour, since I've never stripped a blast before and there were so many JIS screws - which I f***ed two up and needed to drill out)

              I am hoping this doesn't end up taking me 5 months like the universal - it shouldn't as there's no rust damage or patching I need to sort out. It's all in the prep work!

              I also realised why the speakers sounds so crap when I tested it...

              The foam has rotted away! And of course, there's no "easy" replacement speakers for this cabinet - unlike the astro's or naomi universal... the hate for this cab grows daily!


              • #8
                Managed to get some a few hours worth of work on the weekend.

                First had to spray the decal residue with some IPA

                The next 3 hours were spent on hand sanding/feathering on all the areas that had flaking.

                Gave it a good clean with wax and grease remover before putting on the first coat of primer!

                Can already see the massive difference in this area

                And of course... I ran out of primer as I was getting to this side.. *facepalm*


                • #9
                  Looking awesome so far. Will definitely be worth the effort


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