Virtual Boy repair log #1

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Jan 212012
 

Got a Virtual Boy the other day with the Flash Boy Plus cartridge.
The unit worked fine with the Red Alarm game that was already on the cart but when I changed the game to Bound High I was greeted with a solid red screen. The music played and I could run the game blind but that was no use.

I reflashed with Red Alarm and after a couple of screen artifacts in the left screen the game played fine.
After a quick Google around it turns out that this can and will happen to every Virtual Boy made and occurs when the glue holding the FCC ribbon deteriorates so that connections become unreliable.
There are a couple of different fixes for this. One is to strip the plastic back and solder the very fine connections directly onto the board which is a permanent fix, the other is to but the little module into the oven at about 80 degrees C for a couple of minutes then apply pressure to the cable afterwards in the hope that the glue will reset making a nicer connection. This is not a permanent fix but will get you away. The later method is what i opted to do as I’m pretty lazy and dont have the chemicals needed to dissolve the plastic.

The first hurdle is actually getting into the unit as Nintendo kept with the same gamebit screws they used for other devices but they also stuck them down a deep hole so standard gamebit drivers cannot normally reach as they are too fat.
The solution is to make your own from a flat blade driver. I used my milling machine to cut it down and cut a groove in the end. Its certainly not pretty but worked perfectly.

On opening the ribbon cables are on either side of the unit and is held in at the board by 2 little crosshead screws. DO NOT try removing the 2 bigger screws near by, they control alignment.


The top of the cable just pulls out (carefully!).

Get a bit of tin foil, sit the offending article onto said foil, preheat the oven to around 80 degrees C and bake for around 1.5 – 2 minutes.
After its done remove it (its not hot) and rub or apply pressure onto the connection side until its sufficiently cooled and the glue will have reset.
After this, take some sticky tape and apply it to the area wrapping it round so that it applies a little pressure onto the connection.
Refit and test.
This worked perfect for me and many other people have said the same thing.

Time to waste my weekend playing some headache inducing goodness

 Posted by at 11:43 am
Jan 152012
 

Today I decided to make my own SwinSID as I had the schematics and also had the parts laying about.
After a short time checking everything was going to the right places I fitted it into my C64 and fired it up.
As expected it works just fine.
The board still needs cut down to size. I didnt add the ground planes on this one due to some through hole issues.

Thanks to Swinkels for making the SwinSID software

 Posted by at 8:53 pm

Pooyan bootleg Konami 501 replacement board

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Jan 142012
 

Zabanitu has sent me his schematic that has been reverse engineered from the (Konami) 501 replacement board on his bootleg Pooyan.
At this point it is untested and maybe there is even a possibility this will work on a genuine board too?

Here is the Eagle CAD schematic anyway should anyone want to try this out
If you do, please let me know what the outcome was.
Thanks
DOWNLOAD

 Posted by at 2:13 pm

VIC20 repair log

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Jan 072012
 

Got Stiggys other VIC20 the other day, it wont load anything via the serial port and just reports back “DEVICE NOT PRESENT”.
According to Ray Carlsen this can be caused by a dodgy 7406 IC and he wasn’t wrong.

I checked all the states of this chip with a logic probe and all seemed to be as it should be so I went through each gate with a logic pulser and checked for its output. The outputs on pins 4 and 6 were stuck.

Removed the chip and eventually found one on a C64c motherboard that was scrap.
Replaced and tested with a demo and a couple of games.

I also took this opportunity to try out the VIC20 JiffyDOS (PAL).
My original test with JiffyDOS on this failed, nothing would load up. Turns out there is an NTSC and a PAL version, the later being significantly harder to find but we got there in the end.

 Posted by at 5:18 pm

Jumping repair log #1

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Jan 042012
 

Got this Rainbow Islands bootleg yesterday.
The game worked when I tested but was told about a dodgy ribbon connector before buying it so decided to take a look. Not sure what happened after that but the board refused to boot.
After finding a few stuck address lines I decided to check the program ROM’s. Found 3 that would not read properly so I replaced them.
In MAME it lists 2 of the program ROMs as being from the genuine Rainbow Islands set but these are double the size so needed to be split into 2 files and burned to 27512 EPROMs.

Probably worth mentioning that if you use the older 2005 ROMIdent program then the dumps from Jumping actually show up as 2 separate ROMs. Must have been like this at one time.
Booting up now gives me a screen of garbage

Every now and then I could make out a “SCREEN RAM ERROR” message. The screen RAM is located on the second board and suspected this is what happens when the ribbon connector got a bit wrong but couldnt get the game to boot again no matter what I did so I decided to socket the 68000 cpu and see what was going on, kinda wish I hadnt now as I got this

Accepting the error just kept flagging more “tied bits” errors. Turns out this was a red herring as these lines are controlled by a PAL20L8 chip and everything passes if this is removed. Wasted a little bit of time on this.

After taking a careful look at the connector it turns out the plastic housing that holds the ribbon cable in place was damaged and this allowed the ribbon cable to come away from the pins. I properly reseated the cable and tested, the board now fires up in all its crazy bootleg glory

The game plays pretty much like Rainbow Islands does but some of the sprites and names are different and I think the secret rooms don’t work too well.

This game has 3 PAL chips on it, unfortunately all are security locked and I am only able to read 1 of them (might be able to read the one on the video board but never tried).

 Posted by at 7:11 pm