Time Pilot '84

[grobda]

I've been working on a time pilot which had numerous faults, and now has one fault. It was actually working when stored iirc but perhaps got damp struck by lightning and cursed by the lords of chaos. As a result it booted to garbage.

I got the schematics and started out. It was resetting constantly. I disabled the watchdog by removing the 555 at 15H. Its a bit blurry here as this was weeks ago.... I started with verifying the eproms; some were wrong so i burned new ones. Slightly different garbage. Looked at the clock then moved to address lines and with my fancy new desoldering station I pulled anything that didn't look right. Once pulled I stuck it in the ttl tester (handy feature of the vp-280 progger).

after a good long while I ended up with;

faulty 74157 at 3D 4E 7E 8E 9E

think 3D/4E were related to graphics colour errors but cant remember now. I should have kept more detailed records but at the time i kept thinking it would only be a chip or two and id remember before i wrote it up.

faulty 74139 at 7F 9G 16D

faulty 74244 at 11G

faulty 7486 at 14E (all fujitsu branded)

I have to say i wouldn't have got this far without the desoldering station. I don't have a huge stock of spare logic chips so was pulling replacements of a huge and dead raiden bootleg (raiden bootlegs suck they're not worth fixing). All the chips I pulled from the raiden worked. They're mostly goldstar branded. Ive actually used that board to fix quite a few PCBs

I digress... after all this the game booted (YAY)... but with major graphics corruption and no sound (BOO). The game also immediately starded a two player game and marched off northwest on every life, so the inputs were screwed as well.

I was fed up of the bottom board by now so i went on holiday to the top board. Found no clock on the z80, no activity on address lines. Branded the logic probe and schematics and went to battle.

i removed

faulty 74367 at 6B and 9D (fujitsu)

sound burst into life, inputs were still off.

replaced faulty 74367 at 2B (fujitsu)

game now boots coins up and plays with character and sprite corruption. Top board fixed! Now back to the bottom board...

removed faulty 7486 at 3J (f**kingfujitsuasslogic)

characters now clear. NICE. game is playable; BUT.. the last fault... sprites are 'jailbarred' ie odd (or even) vertical lines missing.

I checked the sprite ram at 13/14D they looked healthy - address, I/O, chip select, write enable lines all pulsing. swapped them anyway, no change. found no difference if 13D is present or not. Removing 14D results in sprites disappearing altogether. so problem seems related to this area. checked schems saw i/o goes to custom 502 at 15D, swapped it with known worker, no change.

I wondered if anyone can suggest something here. I'm sure i'll get there eventually but I thought I'd put a shout out. Getting it working at all has been by far the most involved work ive done on a PCB. Its been alternately rewarding and frustrating. I've scratched my head given up and resigned myself to it being dead forever, then bought more parts and come back for more.

I think i've crossed the line from my primary interest being playing the games to fixing them... fixing them is a game in itsself, but at this stage I could do with a cheat code ;D

Oh meant to say if anyone has schematics for the 502 chip itsself so i can figure out what its supposed to do, would be helpful.

grobda2012-02-03 22:04:35

 

[cliff_poole]

It'd be worth looking at those chip selects for the RAM a bit closer, they are pulsing but is the one to 13D doing the right thing ?. I'd look at that inverter at 13H and also check that the tracks haven't been scuffed/shorted somewhere. If you put the RAM back in a socket, you could dangle the chip select leg out of the socket for a bit of experimentation.

 

[cliff_poole]

I'd also check those control lines into the custom.

I can dig my board out and carry out checks if you need comparison.

 

[grobda]

the bastard thing lasted a couple of hours with the sprite fault then started rapidly resetting itsself, so ive shelved it in despair for the time being, but thanks for the input.

if i manage to stop it resetting i'll check 13h and the custom more closely. i could do with a decent scope i guess. ive done a visual check for broken tracks and not spotted anything, it occurred to me a bit of swarf could've made its way under a socket somewhere.

 

[cliff_poole]

I know that feeling only too well

. At least I make notes of everything I do now. I'll occasionally get a board off the shelf and it is obvious that I have worked on it at some point and given up, with no recollection of what I had done. You can't beat the satisfaction of a good repair though.

 

[cliff_poole]

I knew it !, had to double check when I got home though to make sure. My Track and Field has a daughterboard 502 replacement so definately post back if you can get your board back to it's previous state.

And yes !, I do know the PCB feet are on upside down

.

 

[grobda]

BINGO! 7408 at 16F. boots and sprite fault gone!

 

[grobda]

UNBINGO!

now booting to SUB ROM BAD. the eprom for sub rom verifies ok (10d?)

it gives then it takes away... mofo

 

[grobda]

well i can get it to boot by grounding pin 2 of the 244 at 11g.

the game then plays but there's no collision detection between enemies or their bullets and the player ship IE its like a cheat mode. I got 500000 before i got bored. reset and its back to bad sub rom. time for a rest.

 

[grobda]

duh my bad

... did what i should've done 2 hrs ago and checked the last chip i soldered. turns out i made a hairline crack in one of the traces pulling 16f. now got a ugly patch lead to remind me not to rush things

well it works again, thats the main thing

 

[cliff_poole]

Even though they are riddled with custom chips, I do like working on Konami boards of the Konami pinout era, dunno why

.
My collection sort of centers around them, I'll have check my list one day see which ones I still need to complete the collection.

 

[grobda]

I likes em too.

First I got a Track and Field and Hypersports which were both grotty but coaxed into life by reseating a few chips and replacing some physically damaged components.

Then a Road Fighter Bootleg that was a really easy fix (1 gouged track)

Finally I've an Amidar bootleg which is clean and never had a problem with.

Got a slightly faulty original Road Fighter and Scramble incoming (hopefully). I quite fancy an normal Time Pilot too, then there's Gyruss and Juno First.... Mind you theres a few I'll happily pass on; Circus Charlie for one.

 

[Equites]

Nice work dude with the Time Pilot '84.

Those pesky Fujitsu TTLs do have a high failure rate, even on PCBs with very very low use. I had an NOS Ikari Warriors with a bad input buffer which I had to fix first time I plugged it in.

These Fujitsu TTLs tend to fuse internally going open on the outer pins, for that reason they are usually a good candidate for piggybacking.

I just got over my stubborness and invested in a de-soldering iron too, damn why did I not get one of these before?? Now I WANT to de-solder stuff lol, saves so much time and makes harvesting ICs a doddle.

 

[cliff_poole]

When you start looking at it there are loads of them, Konami were very prolific in those days.

I like Circus Charlie, Ping Pong I find strangely addictive too.

Time Pilot is brilliant, had a bootleg for years but eventually got an original only this year.

Tutankham springs to mind as one I'd like to have.