Quick Atari Jet Fighter Repair

So I moved my games around today making space for a new cab and upon turning Jet Fighter back on the score for the white Jet was missing form the display.

A quick browse at the schematics led me to the section below:

/Score1 is the Video signal for the black Jet score and it was pulsing away on my logic probe. /Score2 was for the white Jet and that output (Pin 3 of C3) was stuck high. I checked the input signals and they all looked good so I piggybacked C3 with a new 74LS00 and the score came back. 

I removed the bad chip, fitted a socket and popped the new 74LS00 in and everything is working again.

Sega Outrun in a Power Drift arcade cab.

Part 1.

My newest arcade cab I picked up was a Sega Power Drift, unfortunately both the CPU & Video boards had faults with the Custom IC's, this basically rules them out of being repaired unless swapping the parts with IC's from another Sega board set which very rarely come up for sale... So what to do with a really nice cab, put a cracking game in it that by my reckoning used the same cabinet hardware but different connector arrangement, yes its Sega's finest racer Outrun!

I started off by comparing the wiring pin outs in the back of the user manuals, once these were documented I set about transposing the pins from the Outrun board onto the Power Drift connectors. The Power Drift cab has a filter board that connects all of the cab wiring together, there are then another set of cables that connect to the PCB. This would mean that I just need to make a new set of cables from one side of the filter board to the Outrun PCB.

Luckily for me I had an Outrun loom that I could use therefore meaning I only needed to marry up the wires to the Power Drift filter board using new connectors. The connectors labelled 'AMP' on the Sega boards seem difficult to source, a company called JST seems to produce a very similar connector but I had trouble sourcing these, that's why I decided to use my Outrun loom.. I have ordered some IDC connectors which are a similar connector type as used in PC's for the IDE & SCSI cables. Once these arrive I will make another loom and provide info on what needs to be used as I'm guessing this will be the route anyone else thinking of doing this will go down.

Below is the connector layout that need to be followed:

Every cable with exception of Coin Switch 2 and Coin Meter 2 have been tested and confirmed as working.

Some info below on the connectors I used and where you can get them:

Here's a few photos on the looms I made:

 

The end result is that Outrun plays in my Power Drift cabinet with Force feedback from the motor shaker in the steering wheel mechanism along with all other game IO.

I will update this post with more info when I get the wiring looms remade with connectors that are readily available. If anyone can help with sourcing the JST type connector please get in touch.

Let me know if I can assist if you're going to made a  set of conversion cables, It should be pretty straight forward now the pin conversion is written done and proved to work.

Thank for reading, Mart.

Arcade Garage 14-07-15

Atari Pole Position. Now what's happened with the road!

Well after my last PP fix a short while ago everything was looking good and the game played fine until last week when I was shuffling my cabs around in the garage arcade... When I turned the cab on for someone to play (Hi Chris!) The road had again decided to fail. It looked like the track edge (red & white stripe) was covering the grass on the left side of the track, there was also something going on at the right side of the track edge.

I quickly swapped out the socketed custom IC's which are responsible for the track being displayed, it wasn't any of those :( 

After a checking some more signals I previously looked at with my logic probe I moved to the area in the schematic labelled 'Roadway Memory and Adders'. From the descriptive name it could certainly be an area I needed to look at. Not long into checking signals, I came across signal 'Σ3' (Sigma 3) which is an output from a 74LS283. There are six of these 'Sigma' signals which are mixed in a 74LS298 with some other signals, the output from that LS298 are the address lines of the graphics ROM which contain the track data. Signal Σ3 was stuck always high in comparison to the other Sigma signals which were pulsing away. I removed the IC put in a new socket and with a new IC inserted we were making progress! In honesty I thought this was going to be the 'fix' for the board, but it was apparent there was now something else wrong as shown below.

As you can see above the vertical lines in the track were staggered (i.e. Centre line in track dividing each half) I moved to the schematic section labelled 'Picture Data Memory Address Modifier' and quickly found an LS157 at location 4H with an output that was dead. The signal name was 'MUX2' and this is an input into one of the Custom IC's at location 5L. ( If this custom IC is removed the whole track will disappear) I removed the LS157 fitted a new socket and IC and we have a working Pole position again.

Atari Pole Position. Where's the road gone?

So, my Pole Position board had been working perfectly for a year since its last repair, it's had regular play every week and in my eyes it wasn't a scary event turning the cab on, expecting the a bad outcome.

A few weeks ago I play a game on the cab entered my initials at the high score page and moved onto another game, 10 minutes later I took a peek at the screen and something had gone wrong... The attract mode scoreboard and the title screen all worked fine, but during the screen showing the cars, the track was missing and the background and clouds we gone :(

Grass tracking instead of GP racing.

All the scores, timings, signs and other cars were present, the track had gone walkabout... After a couple of re-powers and checking of test mode for RAM & ROM failures, I knew the board had thrown its dummy out of the pram and would need some attention.

Test setup for testing.Power and video only at this point.

Well after being on the test rig for a very short time, the image deteriorated even more than when it failed in the cab.

Things getting worse...

To me it looked like the 'Green' video signal in the track elements were now missing, the signs and the cars had notably changed colour.

After some extensive google searching for possible faults I came across one post on KLOV arcade forum saying that if the custom IC's 5L or 6L from the Video PCB are removed, you will get the the exact fault that my board originally had.

I did have a spare Video board that had never been powered on, my first test was to swap the two custom IC's around, luckily they are socketed so that didn't take more than five minutes to find I still had the same problem with them swapped out, it would have been unlikely all four were bad so I moved on to some 'real' fault finding.

Video circuit showing the two Custom IC's mentioned above

With a logic probe, all the input and output signals looked busy pulsing away, signals 'PIC1-4' feed into an 74LS157 Multiplexer at location 8C.

74L157 at location 8C on the Video PCB

With a logic probe I moved through the input signal and everything looked well, moving to the four output signals pin four was stuck low while the other three outputs were pulsing away. I fired up my scope to look that what was coming out of the output pins, and even on the three outputs that were pulsing away, there wasn't much data on the signal and the output on pin four was definitely dead.

I did a quick piggyback test and when fires up the green grass seemed to be back and I could see an outline of the track but it still looked pretty messed up. Anyway, I removed the IC, put a socket in and pressed in a new 74157. With finger crossed I powered the game up and was gladly met with the game fully working again. :)

Pole Position lives again

With the game fully working I did confirm that removing either custom at 5L or 6L will exhibit the same fault my boar had when it failed.

Boom! Thanks for reading, more PP repairs to come in the future. I've got a CPU board to look at, it doesn't boot, and I also have a video board that has a graphic fault in the mountains and clouds.

Enduro Racer. Resurrected...

I picked up an Enduro Racer board recently, bought as untested, but expected to be faulty.

Today I decided to see If I could get the game running. First thing I needed to do was check the Security processor to see if the internal battery was still providing enough voltage to keep the processor alive, I believe if this is flat the game will only ever boot to a black screen. I took the cover of the chip and was presented with a leaking battery, measuring the voltage the battery was totally dead.

A leaking dead battery inside the security processor

After searching the web for some info about this issue i came across jammarcade.net Members on there had a whole section of files which enabled you to replace the security processor with a regular CPU, in Enduro's case a 68000 cpu along with updating some of the ROM's.

There were only a handful of ROM's on this board that had labels so I decided to go through the whole board and confirm the checksums were correct and put new labels on.

All the ROM's checked out ok when comparing them to the MAME sets, It took a while as there are quite a few graphics ROM's.

Graphics ROM's galore!

I borrowed a 68000 CPU from a spare Hang-On set that I have and updated the six CPU ROM's that were needed to hopefully make the game work.

68000 CPU replaced and Six CPU ROM's updated with new code

Next up was the need to power the board up and get some video displaying (If the game was going to do that much!) Fortunately my Hang-On cabinet has the same power and video connectors, so I would be able to see if it booted without being able to use any controls. This would do as a start...

My Hang-On cab donating Power an Video

Once connected up I hit the power switch an low and behold the game fires up and seemed to be fully working!!!

With the game powered on the Attract sound kicked in with motorbike throttle and speech which was a good sign, but without coin input/credit wiring I couldn't hear and music, I confirmed in MAME that no music was played during attract mode and then looked at the dip switch setting, there was a 'Free play' mode I changed the setting and when the game was powered back on the background music came blasting out. 

I will probably spend some time knocking together the control wiring IO in the future, the main item I'm currently missing is a cabinet...

Thanks for reading, Mart.

Atari Super Breakout PCB. Back from the dead...

Well a few weeks back I picked up a new cab, a 1978 European (French Built) Atari Super Breakout. Bought in an unknown condition, it turned out the only faults were with the game board (No surprise there !) and the LED on the Serve button being blown. The photo below shows the cab with my test generator plugged in in need of a good clean.

After confirming all the cab voltages were correct & present, I plugged the game board in to be greeted with a black screen and some very faint horizontal lines running across the screen. To get this running in a test rig I re-used my FireTruck/SuperBug adapter as the pin outs for these games are similar, well the Power and Ground signals to make the logic work are on the same pins. I added a few new links on the adaptor to supply my monitor with Composite along with a few switches for Coin-up, Serve and Test.

Now on my work bench, (AKA the Dining room table) the board gave the same symptoms as in my cab.

First I checked using my logic probe to see what the CPU (6502) was up to. Pin 40 of the CPU is the reset pin, this was constantly pulsing high and low when it should be constantly high after an initial low at power on, from this we know that the CPU is not running the game code from the ROMS.

Next to check was the clock circuit, Pin 37 of the CPU is the clock input, this pin should have a nice clock signal on it but there was only a low signal and no pulse. I then went right back to the start of clock circuit and checked the 12Mhz clock and the circuit where the frequency of this is divided down to the Horizontal & Vertical timings that keep the board running in time.

All the H&V clock signal checked out OK which the took me back to looking closer to the CPU clock input. There are three IC's directly involved in making the clock input for the CPU run. As it turned out all three were faulty. A74LS20 @ A8 had a dead output, this fed into a 74LS174 which had a bad output on pin 12, this connected to a 74LS32 which should provide the CPU clock signal, this output was stuck high with no data pulsing. Once all three were replaced and confirmed as faulty, the clock input was looking good, clock outputs 1&2 also came to life now, address bus and data bus lines were active but something was telling me the pulsing I was seeing was not right compared to what I have been getting used to recently while working on board repairs. The game was still resetting.

Following the path of the Address bus lines there was an IC @ F2 labelled as a 3901 on the Atari schematics, the outputs of this device are the PROM select lines. All 6 used and the for unused output were dead, Not high, not low  but completely dead. Researching what this IC was and where I could source a spare I found very little info other that a post in a pinball newsgroup from 2007. the 3901 was a '1 of 10' decoder and seemed to now be unavailable anywhere, to me this looked like a similar decoder, the 74LS42 which is used in other Atari games I've worked on, the only difference seemed to be the pin out, so I had to make an adapter to convert the 74LS42 pin out to fit how the 3901 was wired on the Super Breakout PCB. I decided to know up a IC socket to socket adapter with wiring to convert the pin out. The finished item is below, it's not pretty and at the time I wasn't quite sure if it would work, but it had to be better than an IC with no working outputs.

Pin converter for 3901 -> 74LS42 one-to-ten decoder

Upon power up we now had some garbage on screen, the CPU was still resetting but I was making progress :) All the other important signals which should make the game run were present but again the way the pulsing looked on my probe made sure something else was still pretty sick on the board.

Messed up screen, system still resetting and not running properly

I next decided to socket and replace the eight 2102 RAMs. I have no way to test these so for now putting new replacements in would hopefully help me get the board working, I'd then be able to test them once the board was working. After swapping these there was no difference to the above screen. I decided to try swapping the CPU with a known worker, my Missile Command PCB now comes to the rescue... After swapping the 6502 over the game comes to life! Watching Attract mode shows the blocks disappearing with no sign the balls.

Game now running with invisible balls!

The game wouldn't start or go into test mode and as mentioned there were no balls in attract mode. The Coin, Start and Test inputs are pass through a 74LS153  @ M8, the output pins from this IC were both stuck high, removing and testing it confirmed it was faulty. After swapping the 153 the game would start and would enter test mode. Test mode gave no errors so things were looking good other than the missing balls.

The three 'balls' video signals are derived from a bank of six 74LS163's, piggy backing two of the six with a known good device made two balls return. These two were removed and replaced, the third ball couldn't be found by piggy backing on another '163 but I used some guesswork and removed the IC I thought was the problem, It did turn out to be faulty and once replaced the game looked like it was fully working. The three '163's (Locations R6, P6 & N6) were tested and confirmed as faulty as shown below.

Tester showing faults on 74LS163

Great balls of Breakout! They're back...

Time to put the board back in the cab an check the controls and sounds. All sound and controls worked great.

Super Breakout Back in the cab & fully working.

The game tested out and plays fine in all three modes. Another classic rises from the dead. :)

Total parts replaced for this repair.

1x 6502 CPU

2x 2101 RAM

1x 9301 counter F2 (Replaced with 74LS42) ROM Selector. All outputs dead.

1x 74LS20 A8 Clock circuit

1x 74LS174 A7 Clock Circuit

1x 74LS32 J8 Clock Circuit

1x 74LS153 M8 Input circuit, Test mode fault.

3x 74LS163 R6, P6, N6 Ball video circuit.