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ekorz

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Several years ago I bought two blast city cabs from KC, and though they're both working they were filled with cancer and need some love all around. I thought I'd consolidate some notes and photos into one thread in case someone else wants to get this job done.

Useful resources:
Arcade Otaku Blast City Wiring Guide
Video on dismantling a blast city
@skate323k137 teaching me how to pick dimple locks
How to build a crt discharge tool
How to wash a crt monitor
Nanao MS-2933
Nanao MS-2931

Next, the cabs. Both booted up, one had a bit of a buzz coming from the monitor (note: later fixed in this thread). Neither were perfect on the edges or corners, but a full re-cap did help out. Both cabs were super dirty inside, which was to be expected. Both had jamma looms and 2L12B panels, though I replaced them with lovely reproductions by alberto (https://www.arcade-projects.com/threads/repro-blast-city-yen-sticker-sidearts-and-panel.7285/) though that's not picture below. Here's how they looked when they arrived.

jjZTyMv.jpg
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I'll follow up in separate posts but the goals are:

Simple Green bath for everything, but Krud Kutter first for the dirtiest cancer.
PSU Re-cap including Audio Board
Chassis Recap
Install one as a vertical monitor
New CP's from alberto
Misc: locks, keys, stickers, art
Experimentation
Possible rewiring for other uses
 
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PSU Re-cap including Audio Board

Ian Kellogg's store is still closed, so I ordered cap kits from Arcade Parts & Repair. PSU guide from Arcade Otaku was helpful, and pointed me to buy an Evercool PSU-REP-2PIN7MM replacement fan from ebay.

First up, disassembly. Despite the connector looking quite firmly attached on the inside, it's really just slid together. The four outermost screws were easy to remove (used JIS screwdrivers, not sure if they're Phillips or not...) and after that the PSU just slides right out after that.


otjvKDy.jpg


Then it's just a matter of some case screws to get to the guts. Be sure to unplug the fan, then the side panels each hold one pcb. One side has the power supply, the other has the audio board. There are two screws on the front panel that keep these upright, and one on the rear, then the panels can fold away. You can unplug everything, but each board does have a couple connectors that are the same pin orientation, so keep track of which one goes where.

Then, I doused simple green on everything, and let it sit. If that didn't work, especially on the heavy nicotine stains, Krud Kutter is magic. Then you need Simple Green to remove the Krud Kutter residue... Anyway then finally you can wash it off with some slow running water. You can use, a little IPA to push out some remaining water of anywhere sensitive. Then some compressed air to blow away anything remaining, but I *highly* recommend this XPower air pump instead: https://www.amazon.com/dp/B00SI67YRU/

The recap went smoothly, though a few of the caps were epoxy'd in. I let some IPA sit on the epoxy blocks for a few minutes, and then carefully separated it from the capacitors with tweezers. For the PSU I was able to get to all the caps without removing the aluminum heat sinks on either side (though I did unscrew the top lid).

PSU & Audio Board Capacitor List: https://wiki.arcadeotaku.com/w/Sega_Blast_City_PSU

Here's before and after (though it's the original fan in this photo).

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Chassis Recap

After building a discharge cable, I watched the disassembly video linked in my first post and followed it to cleanly remove the monitor. It needs a bath -- the dirt has grown hair.

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Nanao MS-2931 Cap Map:
MS-2931_cap-map.jpg

Nanao MS-2933 Capacitor List:
from: http://www.neo-geo.com/forums/showthread.php?257925-Nanao-MS-2933-SW-capacitor-list

C721, C203, C232 - 100uf 16V
C407, C401, C381 - 100uf 25V
C406 - 100uf 50V
C971 - 10uf 16V (BP)
C924 - 680uf 25V
C332 - 10uf 250V
C930, C957, C960, C711, C927, C505, C503, C712, C723, C234, C201, C613, C609, C626 - 10uf 50V
C454 - 1uf 100V
C624 - 1uf 50V
C621, C230 - 2.2uf 50V
C922 - 2200uf 25V
C929 - 220uf 16V
C233 - 22uf 50V
C531, C532 - 330uf 35V
C506 - 330uf 25V
C608 - 33uf 50V
C722, C625 - 4.7uf 50V (BP)
C614, C636 - 470uf 16V (I used 35v personally)
C910 - 470uf 35V
C954, C961, C535, C353, C356, C202, C231, C104, C361, C362, C607 - 47uf 16V
C953 - 47uf 250V
C923 - 680uf 10V
C905 - 1200uf 200V
C921 - 470uf 250V
C702 - 6.8uf 250V

I've recapped both monitors. I only had to raise the temps on my tools for a few of the larger capacitors, otherwise everything came of pretty easily. The picture looked better, but the recap did not address some slight convergence and geometry issues I was hoping it would. That took convergence strips.

So I bought some convergence strips... I opted for adding the strips with one hand, while holding a little pocket mirror in the other hand. The monitors had been installed already. I was pretty anxious about having my hands inside with high voltage all around, but I was careful to avoid the anode cap. I still have a few slight geometry issues, but no idea how to resolve them since the OSD didn't seem to have adjustments that cover the situation. The convergence in the corners is much improved though. I added four strips to each monitor. This guide helps with calibration, even though it's about a different monitor: http://www.emphatic.se/?p=710
 
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Blast I/O Recap

I figured the easiest way to wash the cab was to remove everything first. So heck, why not pop out this passive blast city I/O and re-cap that while I'm at it?? I had a bunch of spare 220uf's so I gave it a shot.

tpK6BEw.jpg


This thing was AWFUL to work on. I am guessing all the capacitors are just tied to a big ground plate, and it was very hard for me to get the vias heated with my home workstation. I ended up having to blast an area with a heat gun, then add more direct heat with my iron, which had a large tip too. Even then I'm not really that happy with the end result. I probably would skip this next time around, or send it to someone.

If anyone has tips / experience with recapping this guy, lemme know! I was very surprised... 6 caps should have taken me like 6 minutes. Instead it probably took 60.
 
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Some more brief notes:

https://wiki.arcadeotaku.com/images/3/34/MS-2931_Service-manual_full.pdf Service Manual for the 2931
P.46 covers Factory Service mode, but you enter it by holding all three OSD buttons down (start with up/down then hit mode, then hold) for 3 seconds

Buy a repro CP from @alberto1225 or @Rbtamanini they both make excellent ones. Mine are from alberto, I'm quite happy. Jasen's Customs had some for a while but they scratched too easily.

The best Jamma loom is this one, with line-level stereo built in and switchable via some connectors: https://farm4.staticflickr.com/3730/12942452644_3da5227311_c.jpg
 
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Awesome stuff. I did the cap list for the blast psu and audio amp, @codecrank put it in the AO wiki, and another member (I can't remember off hand) put up the digikey part numbers from my order. Glad to see a store offers that kit now.
 
Awesome stuff. I did the cap list for the blast psu and audio amp, @codecrank put it in the AO wiki, and another member (I can't remember off hand) put up the digikey part numbers from my order. Glad to see a store offers that kit now.
oh nice. I'll try to hunt that digikey list down and post it up top.
 
To discharge the monitor, did you hook up the wire to the chassis or into the actual ground? I'm thinking of recapping my monitor and maybe give it a complete cleaning as well. I just don't want to end up messing up. I'm glad I found this thread of yours. I can buy a kit for the PSU and the sound amp pcb. Seems like there's no kit for the monitor PCB. I guess you bought all those capacitors separately?
 
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@imfuraisoth my discharge tool is a cheap car battery charging cable that I cut and soldered into a groove on a screwdriver. Overkill, yes. The terminal clip goes onto the monitor frame, and the screwdriver tip slides under the anode cap. There are a ton of vids on YouTube that you can watch, just search for “discharge crt”.

cap kit for the monitor (is yours 2931?) but it is worth checking the kit once you get it: https://www.arcadepartsandrepair.co...ms-2931-series-monitor-cap-kit-105c-nichicon/

why check? They sent me one cap that was the wrong size even though it was the right level. They also had a typo on the instructions though hopefully they fixed that after I emailed them about it! Be sure to order the filter caps too, they’re separate.

also... some of this info didn’t age well. I’m updating some of it :P
 
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Just want to pop in and say thanks for this whole thread. Will be a huge help when I decide to tackle mine! 🙏
 
17131E24-0777-4D51-892C-1796E4E72179.jpeg


@imfuraisoth my discharge tool is a cheap car battery charging cable that I cut and soldered into a groove on a screwdriver. Overkill, yes. The terminal clip goes onto the monitor frame, and the screwdriver tip slides under the anode cap. There are a ton of vids on YouTube that you can watch, just search for “discharge crt”.

cap kit for the monitor (is yours 2931?) but it is worth checking the kit once you get it: https://www.arcadepartsandrepair.co...ms-2931-series-monitor-cap-kit-105c-nichicon/

why check? They sent me one cap that was the wrong size even though it was the right level. They also had a typo on the instructions though hopefully they fixed that after I emailed them about it! Be sure to order the filter caps too, they’re separate.

also... some of this info didn’t age well. I’m updating some of it :P
Oh man I wish I saw your message earlier. I didn't find a cap kit so I went and bought each capacitor individually. I'm hoping they are the right size... It was also more expensive than that kit too. Bummer. Does the wrong size for the capacitor matter a lot if the level is correct? Which ones are the filter caps? Is that in the parts list in the beginning of this thread?
 
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For many of the smaller caps if you just went with long life / high temp / premium you should be fine, unless you bouhgt something physically the wrong height or that has the wrong pitch for the legs. The capacitance needs to be the same, the voltage rating the same or higher. But for anything touching power I usually make sure I'm buying the same specs as the original. The filter caps are the largest ones, like 200v or more, and again I'd look for the exact replacement, or I'd look at the spec sheet to find out what it was doing with regards to ESR and ripple.

There are 3 bipolar caps, make sure you bought that version and not polar. Also unless you're a wiz I'd be buying elecrolytic caps again, not trying to swap out ceramics with the same value or anything.
 
Yeah I got the elecrolytic caps. I just matched the capacitors with the same capacitance and voltage when shopping. I'll double check the specs when I open it up. I might just end up buying that cap kit as it's not that expensive anyways. I did get the 3 BP caps too.
 
One thing to look after when buying capacitors is not to go with the cheapest China caps. They are usually worse than those 20 year old quality Japanese ones. I tend to got with these brands and never had any problems.

  • Panasonic
  • Rubycon
  • Nichicon
  • Hitach
  • United Chemi-Con (Nippon Chemi-Con)
And I usually buy them in larger quantities, in many cases the price drops half when buying double the amount. This I only do with most common values (1uf,10uf,100uf,220uf etc.) and I buy them larger enough voltage so I can use them on lower values too. Those cap-kits in Console5 are good but I still can not understand why they lack some caps??? Wtf man, here is 90% of the caps you need, go buy those 3 from Mouser and now you have to anyways pay that postage to two different places??? I just rather order all of the caps from Farnel and only pay postages once...

Related to cheap chinese caps...
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I started recapping my monitor. I noticed some of the capacitors I bought are rated at 85 degrees C instead of 105 degrees C. I'm hoping that won't really make any difference. If anyone else knows better, let me know. When I was buying capacitors, I was generally trying to buy the best ones.
 
They’re likely fine, functionally, they just don’t have a long of a life expectancy.
 
One last question. I'm almost done completely recapping my monitor except for the daughter board. I'm not exactly sure how to get it off to get to the back side of it to recap the 2 capacitors on it. Do I just yank it from the mount? I'm afraid to use too much force.
IMG_2446.JPEG
 
It is hold by that white connector. I used some very thin flathead to push that front plastic "outwards" and then pulled the board off. There are small taps that hold it, so I suggest that you try to loosen it a bit while same time puling it upwards.
 
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