Happy new year all. 

Nice fix  

Thanks

Here's another fix I did this morning...

Atari Jet Fighter. What's the score?
So another week goes by and my Jet Fighter board has another failure, these 40 year old 74 series logic seem to be dropping on a regular basis from being powered on for a few hours here and there...

This this when I started a game, the scores didn't reset to '0' for either player, when I scored some 'hits' on the other Jet the score moved in an odd sequence something along the lines of 2,3,2,6,4,11.

Out comes the operation manual and my printed schematics. The scores are initially generated by two identical circuits comprising a 7493 binary counter, Pins two and Three which are linked to the 'START' signal are used to reset the counter to zero when the game starts. Pin 14 is the counter input which is pulsed when either Jet is 'Hit'. The output pins hen count upwards to a maximum of 15 and pass on to some more circuitry.


Jet Fighter Score Counters

After playing a few games I noted the following... the score was being reset every time a game was started, just not to zero, and it was actually counting, just not in a sequential order, I made the assumption that these two counters would not be the issue as having two different IC's fail at the same time was improbable, If one of these had failed it would seem more likely that one of the scores would stop working and not both at the same time.

The next part of the circuitry that relates to the scores is shown below:



Jet Fighter Score selecting

The 74157 at location A5 receives the signals from the two 7493 counters. I used my logic probe to test the pins of this IC. Pin 1 was pulsing away as expected and the input pins were all the in the same logic state as the output pins from the 7493 counters. There are  four output pins used which feed into a Prom which selects the Score number data, by my testing, pin 12 which is output 4Y on the datasheet was stuck high all the time. Quickly piggybacking a new 74157 cured the scoring, but did seem to have a side effect of resetting the game a short while after stating a new game. Anyway once socketed, I put in a new 74157 and we're back to fully working again. My IC tester confirmed that output 4 of the IC was faulty.

Well after close to four years since moving house, all the cabs I own are (touch wood!) working, Well I need a new starter for my Tempest Fluorescent light, but thought I best capture them while they all do work. My current line up consists of:

Fire Truck, Jet Fighter, Electrocoin Midi with a dual JAMMA adapter playing Pac-Land & Wonder Boy, Tempest Cabaret, Centipede Cabaret, Hang-On and Pole Position.

On the way to getting my current lineup I’ve also owned the following cabs: Outrun Mini, Midway SI, Nitsi Cocktail converted to Arkanoid, Zaccaria Cocktail with Phoenix, Lethal Enforcers, Cruis’n World, Missile Command Cabaret, Asteroids Cabaret, a Popeye Pachislo & 2 JAMMA cabs.

Photos below and a video, sorry for the lack of commentary but I’ve got a stinking cold at the mo and the vocals don’t sound too good.

Can't seem to get the video to embed in the thread but here's a link.

http://www.youtube.com/watch?v=xkI3WyQLRY0






ATARI Hot Wheels!

Actually, Pole Position is a GREAT idea. That game only requires a single DS1220 to save scores. No rom modding at all.

You'd probably be top of the list!

You posted some cracking scores on Twitter earlier today John. I can get around 58K. Way behind... This would be a cool game for an on-line scoreboard.

That's an Atari built Hang-On!

Looks totally fixable, the screen bezel looks in good condition with little cigarette burns.

For any new perspective owner, there's a new Freeplay and High Score save mod to be released soon. I've been testing it recently.

I don't need another HO cab but someone must want it for the price.

I guess it could be shilling from the U.K. but the plug was like the one below.

It had defo been somewhere other than the UK. I'd have thought this would have been updated to suit its location.

Enjoyed the interview at the end and the talk of Qbert. Good stuff!

Ten Pence Arcade is now a solid part of regular podcast's that I commute to work with.

So are these Midway cabs known to have often failing PSU's? WOR is on my hit list as a cab I want, great game.

I'm all for keeping cabs original, with the only exception in my collection being Pole Position which is known to draw a heavy load off the two ARII PSU's and failing often. I fitted a Switcher PSU in a tasteful way without cutting existing cables and am happy with the results.

I'd rebuild the existing PSU (Which you seem to be doing) before looking at alternatives.

Regards, Mart.