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Konami Aliens Repair


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Another quick repair log which is another Fujitsu repair so there's not going to be any long dribble about the why's and what fors.

Only tools used was a Logic Probe and desoldering and soldering iron.

 

IMAG0611.jpg

A kind of a before shot although several IC's had already been replaced plus the ram at G21

I've had this board for several years and as per above several IC's had been replaced, I think I lost interest in this game because A. there was no schematics available at the time and B. It's not a game I was really interested in (and nothing has changed).

This has the Japan set of roms on board (Jap set 1 in Mame) and is based on the TMNT hardware but uses a custom CPU

IC's previously changed.

74ls153 @ G12,G13 and H13

74ls273 @ D15

74ls157 @ C21

The 1 meg rom @ C42 has also been replaced.

 

Symptoms: White screen

Not the common watch dogging blinking white screen. If I piggy back rams on E14/E15 i can see a garbled screen with G21 BAD.

I started by removing the G21 ram and putting it in a socket, strange how this game uses the larger version of the 6264 for the main program ram but the rest are the thinner package...anyway replaced it with the thinner version.

With the ram out of socket I probed the data lines revealing something was pulling pins 16 and 17 high. The only solution is to remove all the connecting IC's until finding the culprit. I started with the 2 74ls245's @ G19 and B20, no change. I then moved to the 74ls253 @ B18, nope. Finally I replaced the last 2 74ls245's @ G14 and G15, game now boots to ram/rom check and ram E14 and E15 register bad.

 

IMAG0616.jpg

Keep in mind I still have the rams at E14 and 15 piggybacked otherwise I still get a blank white screen.

Further probing

74ls157 @ D16 pin 7 and 9 dead the rest of the outputs are stuck low.

74ls273 @ D14 pin 6 dead.

74ls153 @ outputs dead.

 

IMAG0630.jpg

Replaced 72ls157 at D17 and E17, game now boots and without the need to piggy back the rams, I'm guessing the piggy back rams were boosting the signals to the failing 273 register :unsure

 

Graphics look good, no sound except a constant ticking noise.

Cant coin or start a game although service switch works. Dips also not working except those connected to the already replaced 74ls245 @ B20. The rest of the switching is connected to 4 x 74ls253's which I can tell you now most are bad without even having to probe them.

 

Found dead output pin 6 74ls74 @ F10 piggy backing IC I get coin sound by using the service switch. I can't enable attarct sound because the dip switches don't work.

 

Replaced all 74ls253 @ B16,17,18,19. No point doing it by half's, if half the multiplexers/selectors used for switching are dying then the rest are bound to fail. Good tip for all Konami games of this era.

Replacing these IC's I regain all dip and switch functions and can now fully coin and start the game.

 

Sound Issues.

Replaced the 74ls74 @ F10, I now have music but missing speech and other digital SFX, suspect bad mask Rom @ D5 (I also replaced the 74ls74 @ G14 for good measure even though it was ok.)

 

Probing the mask rom all data lines are dead. On the board it says 2 meg mask rom but unless this is a custom chip I suspect its a 4 meg, as far as I know there's no 2 meg 16 bit mask rom equivalent eproms and also in the schematics the mask rom has MASK 4MA written above it and I noticed the highest address line A17 is already tied to ground using the lower half of the rom.

 

I removed the mask rom and replaced it with a 27C4100 with the rom named 875b04.e05 in the mame set. I'm pretty sure this is suppose to be 875b04.d05, seems to be labeled wrong.

 

Anyhoo Sound now 100% game now 100% :)

 

IMAG0629.jpg IMAG0628.jpg IMAG0619.jpg

 

Wow what an effort getting this board going.

IMAG0631.jpg IMAG0618.jpg

Pic's of the board with all IC's replaced circled and the "naughty pile" I really need to replace the remaining Fujitsu's but I'm feeling lazy after this repair. If nothing else I hope it helps other tracking down specific faults with their boards.

 

Big thanks to the AA member who I read contributed the schematics.

Edited by Arcade King
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  • 4 weeks later...
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Maybe you should read this first.

 

http://www.aussiearcade.com/showthread.php/3585-AUSSIE-ARCADE-TRADING-RULES

 

Regards,

 

Johns-Arcade.

 

Thanks John

I've already deleted one post in this thread and he put up another, I'll delete it again tomorrow.

Whitewater as John said read the trading rules, this isn't the appropriate place for sales.

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I am very sorry. I am only new to Aussie arcade and I did not know I was not allowed to offer anything for sale. I did not mean to offend anyone. Thank you for directing me to the rules. I thought that the reason my earlier post did not show up was because I had made a mistake posting it.
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I am very sorry. I am only new to Aussie arcade and I did not know I was not allowed to offer anything for sale. I did not mean to offend anyone. Thank you for directing me to the rules. I thought that the reason my earlier post did not show up was because I had made a mistake posting it.

 

Don't worry about it as soon as you get your 30 days of membership and 30 posts you can sell what ever you like.

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