Apr 302019
 

A friend of mine sent me a couple of Vanguard pcbs which didn’t sync at all on all monitors I tested.

The only difference I saw was that his pcbs were Centuri versions while my pcb which synced good was SNK version.

Centuri versions on the video board have a factory mod with some flying wires which are not documented on the schematics and which are related to the sync circuit.

 

SNK version has no flying wires on the video board:

offcourse undoing the factory mod on the century board fixes the sync problem but I wanted to learn something more.

It seems that Centuri versions were modified to use the positive sync monitor supplied in their cabinets and probably they also improved the sync

signal in comparison to the original circuit.

Anyway , if you want to keep the mod but invert the sync for common monitors or TVs, you have only to solder the wire which goes to pin 3 of the 74LS05 marked in red

to pin 4.

 

Apr 302019
 

While cleaning the storage I found a very interesting power supply made by Sanwa and marked SNW-7E which works with 110 or 220V

The model SNW-7F is the same model working with only 110V

It’s a very nice and compact power supply ( with a tendency of getting really hot!) and I learned that it was used on the most famous japanese superguns .

When I powered it up it worked but on the -5V line I got -7,5V .

I decided to try to repair it and fortunately the -5V was given by a 7905 regulator with few parts around.

I immediately noticed that the regulator didn’t regulate at all since it passed exactly the same voltage on the input on its output.

Replacing it with a new 7905 fixed completely the problem

 

Note:

it turns out that this power supply is just a rebadged version of the RT-85A model made by Taiwanese company Meanwell

https://www.meanwell.com/webapp/product/search.aspx?prod=RT-85

 

 

Apr 292019
 

It’s big, black and squared.We are talking of the ’85H001′, a custom IC you can find on some arcade PCBs manufactured by Capcom like Ghosts’n Goblins, Legendary Wings, Section Z, Trojan, Gun.Smoke.It looks like a module with audio functions, two versions have been made.A ceramic unmarked one :

And a plastic/epoxydic one marked ’85H001 5H’ or ’85H001 5I’ :

Technically speaking the ’85H001′ can be considered a nearly complete digital sound system, all typical components (CPU, RAM, address decoder, etc.) are embedded into it with the exception of the ROM and synth ICs which are external.Actually the ’85H001′ has been already reproduced by ‘Apocalypse’ who made an excellent thru-hole version :

You can read more about in his blog :

http://arcadefixer.blogspot.com/2018/02/capcom-85h001-sound-module-reproduction.html

http://arcadefixer.blogspot.com/2018/07/capcom-85h001-sound-module-reproduction.html

 

Having found recently  a bootleg of Ghost’n Goblins with a module replacement I decided to make my own reproduction and I made two versions.An ‘hybrid’ one with thru-hole Z80 CPU/RAM and surface mounted ICs  :

And a full SMT version with Z84C0006 CPU (PQPF44 package)

Here’s final testing of both on my original Gun.Smoke PCB:

 

 Posted by at 6:41 pm
Apr 282019
 

The Konami  ‘501’ is one of the many custom ICs you probaby encountered when dealing with PCBs from this manufacturer.Most of times the chip (28 pin 600 mil DIP package) comes with scratched-off part name, sometimes not like on my Rush’n Attack PCB:

It can be found on not so many PCBs like shown on this useful spreadsheet (credits to ‘mattosborn’ on KLOV forums)

https://docs.google.com/spreadsheets/d/1iB9BJaEpAufgKaz758FiDDekUH8JreoTn276yPqD-kk/edit#gid=0

Actually there is already a reproduction of it which uses the ColinD CPLD 28 pin board (based on Altera EPM7064S)  of which ‘Porchy’ wrote the code (available here for download).I simply made what I call a ‘poor man’s’ version using simple surface mounted TTLs gates:

Here’s final testing on the Rush’n Attack PCB:

 Posted by at 5:06 pm
Apr 282019
 

Some weeks ago I bought this game for my collection in really great conditions.

While playing, I messed up with the external potentiometer of my supergun and menaged to detach it for a brief moment . Result was that the power supply jumped to 7V on the 5V line and 18V on the 12V line.

With my surprise, the game was not totally fried, sprites were still good but all the background was totally black

Also the game had no sound ( but the amplifier was still good)

For the graphics problem, 2k sram @H15 and H16 had all the data lines in the grey area.

Changing them restored completely the graphics.

 

 

The sound had also another UMC 6116 sram and the data lines were completely in the grey area.

 

Changing it led to no improvement but after checking the connections I found out D6 line was not connected to the Z80 but only to the YM2151.

I probably broken it during the exhange. Restoring the line led to a fully working game.

In the end it appears that UMC parts were the weakest devices of the pcb , I replaced all the ones which were present on the pcb