Got some CPS1 stuff today. There are a couple of populated B boards and a couple of unpopulated B boards.
One of the boards is Quiz Tonosama no Yabou 2 – Zenkoku-ban which I believe is the Japanese version of Quiz and Dragons.
The PAL off this B board is labelled TN2292.
On one of the unpopulated boards was a PAL marked QAD63B which im guessing is from a Quiz and Dragons board. Ive dumped this anyway but it remains untested. I cant even find a reference to it anywhere online.
Stiggy gave me an Atari 2600 he had going spare when he came round.
Ive never owned one before but its always been on my list.
The old 2600 only has RF out which is completely rubbish on modern TV’s so it was off to the internet to see what kind of mods exist.
After a short while of checking different sites I came to the conclusion that there is no decent, definative guide for my version of 2600.
My mainboard seemed to be a little different in layout than what the guides were based on.
Looking at the other guides they show that the video signals all come from one IC which is standard across all the 2600 models so I traced out the SYNC, LUMA0, LUMA1, LUMA2 and COLOUR signals myself and ran some wires from the points and to the outside world.
As you will see, there is a “COLOUR” label with thats crossed out. This is because I originally followed the circuit through the resistor where I should have followed it from the resistor up to and through the capacitor above it. I ended up tapping into a +5v line by making this mistake so ended up with no signal at all.
I made a quick design in EagleCAD and etched a board based on a simple transistor based amplifier running the LUMA signals through various size resistors.
After taking my +5v from the nearby voltage regulator, fixing my mistake that I highlighted earlier and doing a test with a loaned Harmony cartridge I saw a fairly decent image on screen. Its a little dark and this can probably be changed with fine tuning some resistor values but this will be more than acceptable for me.
The pictures don’t look too impressive on the photos but they are a joy compared to RF.
Ive yet to hook the sound up but the wire is there for it, this will be tomorrows job along with properly fitting the phono plugs.
EDIT: Sound is now hooked up and fully working. All phono sockets are fitted. What a nice mod it was.
As with all VB’s and in my previous repair, one of the screens goes a little strange, in my case it was the left screen.
I initially used the oven fix method which worked well but only for a short amount of time.
I fired it up today and was greeted with the same left screen showing garbage.
Rather than use the oven trick again I decided it was time to try one of the more adventurous methods out there.
Turns out there is a nice video on YouTube of how to fix it using a soldering method.
Instead of dropping a load of solder onto it I used some liquid flux and a small amount of solder. You can see it working quite easily and no braid was needed to mop up the excess.
The whole thing only took a few minutes and worked perfectly when I put it back together.
Time will tell how long this lasts but I don’t see why it should cause issues again.
Stiggy dropped round today for a cuppa and brought his sick Master System with him. I have 2 of the mark 1 MS units so we did a swap.
Basically this system was always seeing the UP direction pressed on port 1 even with no controller connected.
Looking at the schematics it would appear that the custom IC 315-5237 has an internal pull-up resistance on each pin and the controller grounds this to register a button press. As I found the pin giving out a permanent low signal chances are something has gone wrong internally.
What I did was fit a resistor between this pin and VCC which changes the default state to a logic HIGH but will still allow the controller to drive it LOW for the button press. Almost certainly not the ideal way of doing it but I don’t know the MS very well at all so this will have to do.
The system now works perfectly. This MS also has a couple of built in games which my old one didn’t.
!
During my random internet searches I came across some PAL dumps for a rare version of an Amiga 1000 motherboard.
I still don’t know completely what this board does over an original.
After contacting a few people from the forums asking for permission to offer these up for download I was given the name Andrew J Wilson who is the developer of the board.
I cant seem to find this guy to ask his permission so, Andrew if you ever read this and aren’t happy with me hosting them just let me know.
The files are in a .zip file and there is also a dump of the SCSI controller EPROM in there.
Thanks to jopower from the a1k.org forums and DonutKing from Vintage-Computer.com forums for their help.