Friday, 30 March 2018

Atari Video Pinball PCB repair missing playfield bits

I decided I needed to play Video Pinball today, its not been turned on since my time off work over Christmas. Well the game had decided to go a little bit faulty, I didn't immediately notice, but there was a section at the top of all the game text that had been chopped off, the four game flippers also had a black line running though them.

The game played fine apart from these graphical errors, test mode reported no errors. See the photo below showing the faults I mentioned. You can see the lines in the flippers and just about see where the top line of the text missing.






































The Circuit for the Playfield is a fairly small section of circuitry. The CPU writes data into RAM that defines the Playfield picture, the Sync timings then select this data which in turn addresses the Playfield ROMS (C5, D5) with the data from these passing through a shift register (C6) where the output is mixed as part of the final analog output video.

Using my trusty logic probe I checked all the clock signal and confirmed all address and data lines were active and not stuck high or low. Well I couldn't see anything the would normally highlight a fault. Thinking more about the fault, I deduced it was unlikely to be the RAM or ROM at issue; when the flipper button was pressed the graphic moved perfectly and wasn't corrupt as such, if the ROM(s) had gone faulty the missing line would move when the graphic was rotating.

Looking like a fault I had seen in another repair, I decided to remove the 74LS166 shift Register so it could tested in my MiniPro programmer, my hunch was correct and it was declared as faulty.



So despite having over 80 pots with different IC's, I didn't have any 166's, I 'borrowed' one from a Super Breakout PCB which has become a bit of a donor for random parts I've needed to use...

With the 166 replaced the game is back to looking and playing perfectly again.


Until the next game breaks, thanks for reading, Mart.

Sunday, 18 February 2018

Atari Breakout - PCB Repair

A few months back I offered to look at a few Breakout PCB's from a forum member on UKVac.com, they were in an unknown state but the owner has an Atari cab and it's no fun having a cab with broken PCB's. Challenge accepted!


Once they arrived I made a quick overview/assessment of the PCB's. There were two Atari PCBs and a bootleg/clone board, here's the info about the one I repaired in this post.


Atari PCB1 (Orange filter cap) - Factory Wire mods.

Missing LM323 and heatsink.

Missing Electrolytic Cap - C22 10uF

Missing J1 - 74174 - Sync & Video Combining for final output stage.

Missing E9 - 7404 - 1/2 Player start logic, 2player control logic.

Missing R50 - Volume pot 10K

Pin 4 underside of edge connector burnt away. Wire link mods made.

I decided to tackle what I call Atari PCB1 first, the owner was keen to have an original PCB so the bootleg was left to one side even though it was now known to partially work.


I fitted the missing 74174, 7404 the Capacitor at C22 and the missing volume pot. at R50.


I hacked some power wires to the PCB for the 5vDC logic, I also added 12vDC in place of AC to run the audio circuit.



The game fired up on my test monitor, the scores would flicker and there was an odd ripple that would move through the video image, mainly showing itself on the left side of the screen. This turned out to be a 9312 at K5. I had to remove one of these IC's from the other Breakout PCB as these are now obsolete and there is no direct replacement. Once fitted, this fault was fixed.


Something I noticed was that the video signal was not showing bright whites as I was expecting to see, it was more of a Gray colour and didn't quite look right. 

After looking at the values of resistors in the final video section where the different parts of the video are joined (Playfield, Scores etc.) I noticed all the resistors were different values to what is shown on the schematics from the operations and maintenance manuals available on the Internet. This is a Revision C board while the schematics I had were for Revision F, there are a handful of factory wire mods across the PCB which must have been fixed in later revisions.

I changed 4 resistors and added a 5th that is shown in later PCB revisions and the image turned into the bright white I was expecting.



At this point I populated the missing LM323K voltage regulator along with heatsink, all that was left to do was fix the Edge connector, something I'd never tackled before.

I had a  gentle scrape to remove all the old burnt mess and was left with the following:


I decided to use Epoxy glue to 'fill' the PCB back into the size it needed to be, as some of the PCB had been eaten away by the burning.



The photo above shows the area masked off and filled with glue, this was left for a day to cure hard. Once sanded it was looking better, I just needed to replace the copper tracks.


I used some self adhesive copper tape which I found on ebay, I simple purchased a 'sample' for 99p which will give me a lifetimes worth of tape fore edge repairs, once applied (I used very small amounts of epoxy glue) I used some old cut offs from capacitor legs, to loop through the board where I would solder onto.


Once soldered into place it looked good and I'm fairly confident it will be strong enough for normal use.


So that was it. I tested the game for all functions and it's ready to be returned to its owner. Another PCB saved to make an old arcade live again. Thanks for reading.












Thursday, 9 November 2017

Dino King Conversion: Dino V Asteroids

So I converted a Sega Dino King cabinet to play one of Atari's greatest games; Asteroids, this is my one post completed conversion thread :)

Before:


After:






Now for the back Story...

This project started a fair few years back after purchasing one of FrancoB's steel Dino King reproduction control panels. I went for a blank panel as I could see the potential to create a conversion of these tiny cabs at some point in the future even though I didn't own one at the time. Not knowing what it would be, I could always cute holes to my design in the future.

Fast forward another few years and I had the chance to buy a Dino King cab from a local friend. Most of the original hardware had been removed before I got my hands on it, all that was left was the metal cab, monitor, power transformer, metal brackets and internal shelving, it was a good solid cab but it was never going to play Dinosaur King again!

So what was I to covert it into? At the time Pac-Land, Ordyne and Wonder Boy were high on my list of idea's, I had the original PCBs for all of these games and thought they'd work well in the small form factor these cabs have.

Well I didn't end up converting it to any of those, there's a long winding tale to how it ended where it did but it briefly goes like this. I traded my Atari Pole Position cabinet for a Saga Outrun cabinet. The Outrun was a bit more of a project than I'd hoped for, I took the working Outrun PCB out and used it in a Power Drift cab I had picked up, and then traded the the Outrun cabinet for a complete set of parts to make an Atari Asteroids.  

So I pretty much had all the components needed to play Asteroids and yes that was going to be the game my conversion was for.

I decided that first I would need to get all the hardware working.

Here's a list of the bits that needed fixing; The game PCB was faulty, the Deflection PCB on the monitor was faulty and typically for me the Atari Power brick that provides the AC voltage to the monitor didn't provide the needed voltages for the black and white vector monitor, so I would have to make a work around to get the monitor powered. Along with the conversion of the cab itself I had a lot to do and that's why it took me a few years to get it all done.

After the hardware was working (the PCB was repaired elsewhere and I had a Meteorites Bootleg PCB for testing with) , I stripped out the remains of the Dino cab and laced in the Atari wiring and made new mounting plates for the Atari parts.




The basic layout of the wiring loom was partially completed before the components were removed for powder coating.



Next up was the need to layout the control panel mounting for the buttons. Olli (muddymusic) had kindly been working on making so custom art to fit the Dino size and layout for me since December 2015 when I first discussed the project with him. I got what we'll call revision one of the overlay and temporarily fixed it to the met control panel. with this in place I marked up the button holes and proceeded to to press out the button holes with a tool Vic Marland (Virtvic) had loaned me. Well during the cutting of the second hole the tool broke! That was the end of cutting holes in panels and I gave the broken tool back to Vic along with the panel and he finished it off. We realised the button layout of the overlay were too close together and these were widened to accommodate, there were also a few errors in the graphic in the overlay that got tweaked at the same time. When control panel overlay revision two arrived, it was all a great fit and alignment of all the buttons was spot on.



Revision 1 of the CPO shown below, some alignment changes were needed after measurements were confirmed.


I decided that to make this conversion stand out and work well, It couldn't stay painted bright orange! Perhaps if it was DK Jr. I'd have been happy but Asteroids warranted a slightly darker paint scheme. Gloss black was the chosen colour, and my local Powder Coaters did the job within a few weeks.



Having received the art package, I was keen to fit the side art to the cab now it had come back from the painters.




Next on my list of things to do was to concentrate on the plastic monitor surround.

This part needed a small repair as it had been damaged before I received it.



With some strong glue, a piece of aluminium plating and some light sanding, the repair was complete and ready for paint.

I decided on a Satin Black spray which would be topped with some sparkly glitter and clear lacquer.

Primed.



After using one can of Satin Black it was time for some wet & dry sanding.



Another can of Satin Black sprayed on.


Just adding some sparkle with Glitter spray (Very difficult to show in the photo)



Clear lacquer for a lasting finish, freshly sprayed and still wet.




Control Panel, monitor surround and perspex front all assembled and ready to meet up with the rest of the cab.


Next year I plan to refurbish the Power Brick, the AR PSU and the monitor Deflection and HV PCB's to hopefully give increased reliability over the coming years.

Some misc photos from throughout the conversion.




Anyone know if a 'Cathy N' worked on the production line at Atari. Nice little 'easter egg' in the original Atari metalwork?
















People to thank for this project include:
  • Martin (Milky) For selling me the DinoKing in the first place.
  • Nad (Equites) Who met me at a service station in the pouring rain to trade the Asteroids parts for the Outrun cabinet.
  • Olly (muddymusic) from Arcade Art Shop for his custom Artwork which has made this project something to stand out from the crowd.
  • Vic (Virtvic) from the Ten Pence Arcade podcast for his metalwork skills in punching my control panel layout.
  • Dave Flynn for his wise words on how the original Dino cabinets are wired together, also for clearing out my leftovers of brackets, metal work and odd and sods of Dino King parts.
  • Anyone else I've missed off that should be here! Its been a long road, sorry :)
Thanks for reading, Mart.