Thursday, 8 August 2013

60Hz Snes Mod Overkill

Soo.. feeling much <3 for my recently purchased Snes & Everdrive cart - fitted the DSP1 - all good.

But... the 50Hz borders sucked ass & game the region compatibility seemed hit 'n' miss with the revision of Everdrive cart I have (1.3/6?) So decided to venture into mod-ing the sucker.

Ordered a couple of switches to be collected in-store @ Maplin (and picked up a couple of spares, just in case).. rushed home all excited, and..

Argh!!! :'(

The switches had their third pin missing!! What the hell man!?! There's a hole where the pin should be, but no pin! Why? Just don't solder a wire on it FFS!!!

Hah! Lucky I picked up those red ones off the shelf huh ¦) - But WTF? They're spring loaded!!

Bugger - It would have cost me more in tube fare to go back than the switches cost & felling impatient, I had to find a way - so went rummaging through the parts box.. And found this little lot:

This is how a computer programmer make a toggle switch :-{)} using a 20 MIP computer (The Atmel AtTiny85).

I began by performing the physical end of the 60Hz / Region mods, by lifting some surface mount pins & attaching kynar wire to the relevant points:

I then used a larger (Mega0256) Arduino to write a small program that read two push buttons and if held down for about a 10th of a second would toggle one of two output pins that I attached to an RGB Led to test its behavior.

I made the toggle so that it would toggle as soon as the button was held, but wouldn't toggle again until you released the button (and added de-bouncing code to remove glitches).

Once the code worked I plugged the AtTiny85 into a breadboard - wired the SPI pins to the bigger Arduino & uploaded the ArduinoISP sketch to it.

Re-jiggled the pin numbers to match the smaller chips layout & then sent the code via the Arduino - through & into the AtTiny85.

I made the RGB Led light up blue when the power is on.. and the Red & Green lights would toggle with the Red & Green switches.. So Blue by default (PAL @ 60Hz) - Magenta for PAL @ 50Hz (B+R), Cyan (B+G) for 60Hz NTSC & White (R+G+B) for 50Hz NTSC.

Ran the wires attached to the Red & Green Led pins directly to the mod-pins (The red 60Hz wire ran through a 2.2K resistor iirc) - And mounted the Led in place of the power light with some hot-glue:

Soldered the Led resistors directly to the bottom of an 8pin chip socket, and the blue resistor is the 2.2K one feeding the 60Hz mod - all sealed with hot-glue.

(I left the top of the socket un-glued so I could re-program the chip if I need to in future.)

More glue & insulation tape & job done :D

Super pimped ¦) No borders by default - 95% of games run by default!!

Technological overkill? - Naaaaah...

And....... Atmel AtTiny85's are cheaper than a single Maplin's switch! :o)

Saturday, 27 July 2013

Snes Everdrive DSP1 Installation

Giving the Snes some love today. :)

I managed to get hold of one of those Everdrive cart's :D ..but sadly the one without the DSP1 chip :'(
(which is needed to play MarioKart or Pilotwings)

So to source the needed components I picked up a crappy lesser known US cart called Ballz 3D - a console-mod forum tutorial pointed me at this title - as it has all three of the required components
(And is quite frankly, a load of Ballz!).

So step-one was to get the Everdrive & Ballz-cart open :/

Meh... security screws! :(

Luckly there's a tutorial on youTube on how to melt the end of a biro and push it into a screw (while molten), to make a poor-mans security-screwdriver.. \o/

My first attempt didn't go too well & biro plastic got stuck around one the screw heads, but since I was practicing on the donor cart - there was nothing a hack saw couldn't handle.

Had to desolder three components: a 74HCU04, Ceramic Oscilator & the DSP1 chip:

Care had to be taken when mounting the chips to te Everdrive pcb.. there are several surface mount resistors right next to the IC pin holes!

And - The DSP1 chip has to mounted on the back side of the board & the Logic & Clock on the front!

And the other (front) side:

Reassembled the cart WITHOUT security screws! ;)

Happy days! <3

We have: Pilotwings..

And more importantly..

Retro-tastic :D I haven't had a Snes for over 21 years! I'm old.. :/

Oh.. also worth a mention.. I received an RGB SCART lead with the Snes I bought, but upon plugging into my later-day LCD TV, the screen would fade to black as soon as the picture became busy / too bright.

The solution was to desolder three capacitors that were in-line with the R,G&B wires in the SCART plug.
(I left the Cap on the Sync wire & that seemed cool.)

Recycled Master-System Cartridge

Recycled Master-System Cartridge

Recently received some freebee Master-System cartridge PCB's from steveBM1 over on Jamma+, a very kind fellow indeed!

Went and fitted a 32 pin chip socket to one of the boards and naively burned a 27C020 (256k / 2Mbit) Eprom with Wonderboy 3 game data (love that game - still remember the cheat password: WE5TONE)

But no boot.. :'(

Later learned that Master-System Roms have custom logic inside to page in the blocks of data for games bigger than 32k.

Apparently you can re-use carts that have a second 'mapper' chip, so for now I thought I might try a 32K game burned onto a 27C256 chip.

But............. The 27C256 has 4 less pins than the 27C020 (it's 28 pin, rather than 32)

From experience with the R-Type conversions, I knew that all the lower 26 pins are the same between the two chip types.  So I burned a 32K Eprom with Teddy Boy and inserted it into the lower end of the socket.
I had to then fit 2 wire bridges to bring the 5v line down to the top two pins of the 28 pin Eprom.

I also had to cut one trace that led from the third pin - to the edge connector (Shown below).

And here is the finished board in full:

And again from below:

And you know what..? It worked! :D

Just have to wait for a RGB SCART lead to turn up, my TV won't tune in well enough to get a good picture on RF.

I'll also have to research this mapper-chip stuff.. might be able to build some logic to do this.

Friday, 26 July 2013

Double Dragon - Repair Log - Day 3

Double Dragon - Repair Log - Day 3

Fixed the 1 & 2 player buttons I/O.. and all looks good for this one!

Though on my bartop i do get the occasional sync roll!?! :( .. I found the schematic to see where the sync pin leads to, but if goes off one page & must become Japanese on another. :/

I scoped the signals around the video connector and supply, and I get a god solid 5v power rail, RGB going from 0-1v and the sync line going from 0-2v .. Large 0 pulse (v blank) with finer 0-2v pulses in between (h blank).

I compared the signal with some other boards and it looks legit :D which suggests another theory..

Are the sync issues due to the CGA-VGA converters I'm using on my flat-panel?

Short answer.. Yes. The pcb was verified working by the owner on his CRT.

WARNING! (To anyone working on one of these boards!)

I had to re-fit the four board spacers back between the two boards before it was taken away..

Oh boy!!! :S

On double dragon there are two plastic spacers ... and two metal ones ...  

I placed them in a rather arbitrary arrangement, tightened the bolts & powered up.. 
Wait for it... F***in shite loads of smoke poured out of my Jamma loom!!!

Turns out that.. Well you know the big fat traces that run around the outside of the PCB'S? They're usually earth / ground / 0 volts, right?

Not this time! One surface of each board is 0v and the other is 5v. Two of the corner bolt holes are seperated buy a split in the PCB track (running round the edge) - two are not.

If you get the metal corners wrong then it's smoky time - so please be careful and make a note of where they came from when you take the boards apart!

I assume the metal rods actually carry the power and ground from the top to the bottom board (when in the right corners) & the 0 & 5v on each side of the board is acting as RFI suppression.

Luckily there was no real damage done.. The direct short through the metal board spacer rods protected the board.. I'm just gunna need some heavier cable for my 5v line. ;)

"A dragon with two metal teeth!"

Thursday, 4 July 2013

Double Dragon - Repair Log - Day 2

Double Dragon - Repair Log - Day 2

Okay.. I did something a little silly ..not in a baaaad way tho.

I've bought another broken Double Dragon board on fleaBay to assist in the repair.. (hope I wasn't bidding against Beaps!! :D) - cost £37 all-in - ruuning at a lose, but hey, at least I can keep the scraps.

It arrived last night & I immediately swapped the top board from the new one with Beaps rusted one (remember the resistor pack issue?):

As the one I received locks up on boot, I fitted Beaps brand-new processor & US Rom set:

And... drum-roll....

We have a good picture - all that remains now is the player 1&2 start buttons don't respond, booo.. :(

Bet £1900 some one had previously rear-ended the 12v line.. (reversed the Jamma connector)

There looks to be some previously attempted repairs around this region of the board, so I know where to look first..

Saturday, 22 June 2013

Double Dragon - Repair Log - Day 1

Double Dragon - Repair Log - Day 1

Today Beap's Double-Dragon board that came out to play..

Some repair work had previously been carried out on this board, and it looked like Ram & sound substitutions primarily.. The CPU had also been replaced.

But on power up there was an unnerving buzz for two seconds and blocks of corrupt data in a static pattern across the screen. :(

First I had to remove some rust from the sound side of the board..

And there was a region of the board where a 5-pin-resistor-pack had been previously removed..

Cleaned the rust & crusty flux & ordered some parts..

Will have to completely rebuild the tracks - this damage shouldn't stop the board from booting - but I won't expect the sound to function too well until it is resolved.

And from below:

Also removed a big metal pin that was shorting a transistor:

The soldering around the previous repairs didn't look too healty, lots of dry flux, a couple of shorted traces and maybe even a split track or two. :/

Cleaned it all up a bit.. reflowed the solder - removed all the shorts, and attempted a power test..

It' booted! - Not without issue though.. but its playing and makes a few sound effects on start-up!

Some progess at least.

The sprites & BG-layers looked to be functioning.. looks like the Font layer is glitched - will have to probe those Ram chips, to see if they have to be replaced.

To be continued...

Monday, 6 May 2013

Arkanoid Controller

Arkanoid Controller

Haven't done wood work since I left school, and that was a hell of a while ago.. ;)
So being the bank-holiday I borrowed a drill to put up some garden fixtures & got a little side tracked *ahem* (the garden furniture never did get fixed).

I decided to convert a cigar box into an Arkanoid spinner controller! (hate cigars anyway)

Was lucky in finding a drill bit that fitted the diameter of a arcade button.. (It came with my son-in-law's car-camera kit!?! & he didn't need it.)

Meh - should have practiced, even after marking out the wood I managed to get one of the button holes 1mm too far to the left & managed to chip the veneer (though it will be covered by the plastic plate under the spinner).

Dismantled the spinner & bolted her in..

Gotta love heat-shrink cable wrap!

Used the cable from an ex-Dreamcast pad that I converted to Jamma previously.. 
For brevity I just soldered the control wires directly to the Arkanoid-to-Jamma adapter.
(I'll work out a plug arrangement perhaps.)

Coin-up is still done by the service button on my test loom.. still don't know why all my boards ignore the 'coin' wires & use 'service'?

Just need some proper player 1/2 buttons to finish it off.. but at least for now I can now play Arkanoid comfortably!! 

Thanks (again) to Ben76 (Over on J+) for the Arkanoid power plug & to Rob for the drill bit! :D

Long term I'd like to re-jig my BarTop into being able to have its monitor rotated & then I'll attempt to build a custom CP for this game (with a more authentic layout), but for now... It's all good!

Friday, 8 February 2013

Bomberman World - Repair Log

Bomberman World - Repair Log

Picked up a (rather cheap) iRem Bomberman World (Global Quest) arcade board from eBay today..

Looked visually to be in good condition, but the seller did say it had been stored for a while.

Plugged it into my BarTop and all seemed well.. coined it up & started a couple of games..

But, about 5 minutes things got a little odd.. :S

When ever the game made a loud-bang (such as when the bombs went off) the screen would go all frizzy & wobble out of sync.. & the VGA converter would then loose signal-lock for a few seconds. 

This carried on for a bit, then all of a sudden...

Made everyone jump a mile!! ... The main smoothing cap on the 12 volt line (to the Amp) went bye, bye in a most violent way! (..and the misses got rather pissed off too :/)

Bits of capacitor flew everywhere & hit me in the arm! :(

A nice quick fix though..

De-soldered & pulled the cap out, cleaned the board & dropped in a 40 volt replacement from the spares box (the original was rated 25v).

Will probably re-cap the whole power section at some point, the games a good 21 years old now (no surprise a cap has dried out after all this time).

Have turned the board upside down, in case it goes bang again ;) ..soak tested it & looking good so far. :D

Loved Bomberman on the Snes bitd & played a lot of the PCEngine version - well chuffed to finally own an original iRem version..!