cmonkey has successfully tested the 317-0034 decrypted set made by Runik.
Thanks for the update, cmonkey
Super Hang-On (317-0034) tested
Decrypted Updates
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Apr 252015
Apr 252015
Ive been looking for a cheap small voltage display for a project I’m working on and I turned to eBay to try a few of the cheap ones out.
I dont need anything spot of accurate but an indication of what I’m supplying.
My search led me to this one
It looks small and it was certainly cheap enough at 99p delivered.
It arrived today and it doesn’t look too bad.
I hooked it up to my power supply to check its accuracy and usefulness.
The description claims this thing can display from 2.5v – 30v so lets test those claims out.
NOTE: I really struggled getting a clear shot of the display with the useless HTC One camera and the fluorescent lights but you can make it out.
With the PSU set at 2.5v we get this:
Not bad at all. What happens when we go lower? Well I got to 2.489v and the display starts flickering like mad.
At the lower voltage of 2.5v the display is a bit dim. Perfectly readable but dim.
Next, 3.3v
And 5v
I did a bit of extra testing around the 5v area mainly as this is the voltage I’m going to be operating it at.
I tested at 5.2v
And to check the accuracy I checked it at 5.125v and 5.126v.
I’m happy with that even if I don’t need the accuracy too much.
Next up I tested 12v
20v
Finally I just tested its claimed maximum of 30v
The display gets a lot brighter at this voltage.
This unit I got didn’t need any adjustment but there is a small pot on the back to adjust it if required.
Its certainly not the best in terms of build quality but for my specific needs I’m quite happy with this really.
NANAO MS9-29T chassis repair log #1
Monitor Repair Log, Repair Logs
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Apr 222015
Recently I finally got my first arcade cabinet from my friend ‘robotype’;
For the uninitiated the Astro City is a compact sitdown cabinet released from Sega in the 1993.It’s by far the most popular cabinet in Japan.It mounts a wide 29″ 15/24KHz monitor (Nanao MS8, some have Nanao MS9), its interface is JAMMA so widely compatible with most arcade PCBs.
After redone all the internal wiring and adapted the powering to 100V (main electricity in my country is 230V), I turned it on for the first time and I got a vertically crushed screen:
First thing I done was trying to adjust the vertical size through the pot on the remote board:
but I was not able since the pot was jammed.When I desoldered it, it fell off in pieces.The exact part is a 10KOhm manifactured by ALPS quite impossible to find nowadays so I opted for a generic trimmer:
With the new pot fitted I was able to correctly stretch the image vertically:
But the image was not stable, sometimes it crushed to become a horizontal line so I decided to furher investigate taking apart the chassis (NANAO MS9-29T model).First thing I’ve done was checking all the capacitors in-circuit with an ESR meter and I was able to found one bad which was clearly leaking and whose ESR was out of range of my meter (0-99 Ohms) :
Replaced it fixed all issues.
P.S.
For those interested I compiled a capacitor list of the NANAO MS9-29T chassis.You can view it from here (or download from site)
Homebrew Gameking cartridge
General
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Apr 222015
Today I finally got my homebrew Gameking cartridge working.
Its a bit of a mess as there are several failed original design decisions hacked out.
The idea behind this is to hopefully get the internal ROM dumped so emulation will be possible.
Apr 212015
Recently, I picked up an ‘untested’ Twin Cobra PCB off of eBay. As most of us are aware, when something is advertised as ‘untested’, 9 times out of 10 its completely broken. This Twin Cobra was no exception to this rule.
Out of the box, the game booted up to a flat black screen, zero activity at all. When I see this on unknown condition boards, the first thing I do is give it a thorough visual inspection. I generally look for rust/corrosion, deep scrapes and gouges severing traces, physically damaged capacitors and IC’s, etc. Right off the bat, I noticed the the Koyo 28mhz crystal at X1 was hanging on by a thread! The other three had snapped off at the base of the crystal, so it was time to find a replacement. I was able to find a donor crystal in my parts boards.
I desoldered what was left of the original crystal, and then I installed the donor. The donor is slightly faster than the original, but it should be OK until a proper replacement arrives in the mail.
The rest of the board looked good – no gouges, no other damage so to speak. At this point when I powered it up, the game sprang to life!
Everything appeared to be working as expected, so I coined up and tried a game. Almost instantly, the next fault presented itself. Some (not all) of the sprite layers were incorrect. When the tanks aimed at towards 7:00, their turret would disappear completely. When larger tanks were destroyed, their remnants would take priority over my helicopter.
I knew something was at fault either with the ram or layer priority sections of the video board. From here, I started reading up on the mame driver, as well as the memory map for Twin Cobra posted on Toaplan.org. From what I could tell, it looks like sprite priority is controlled by the bipolar roms present on the TP-011 SUB (graphics) pcb.
I gave the 82S123’s a closer look, the bipolar rom marked B30-22 on the parts side of the PCB had a factory defect! There was a small solder bridge connecting pins 5 and 6. I fired up my soldering iron and removed the bridge.
Fired the board up, all faults were cleared! Game now works 100%. It’s mind-blowing to think that a game manufactured in 1987 has only played properly some 28 years later. This Toaplan masterpiece lives to fight another day! Until next time…
