Centipede repair log

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Mar 062016

After 6-7 years years I decided to dig up my Centipede board (already repaired several times in the beginning) to make a play and I noticed that it was too quite.

Some sounds were present but something was missing…

After firing up Mame I immediately noticed that the sound missing was the centpede one!

After a brief looking at the schematic I understood that the Pokey chip was somewhat faulty.

Started the tone test and the channel 4 was silent.

Luckily I had a Missile Command lying around which was in very bad conditions but the Pokey was good!

So sound fully restored changing the Pokey chip @C3


Stun Runner repair log

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Mar 292015

Had Muddymusic’s Stun Runner PCB for a long long time awaiting repair.
I put off looking at it because of how test bench unfriendly it would be to setup.
I did have most of the original loom to use but the audio section also used 13v AC and a test bench typically doesn’t have that.

I ordered a small 240v – 12v transformer and eventually set to work in hooking this thing up.
After half a day of messing around I had what I thought was a Stun Runner test rig.
While I had all the connections going to the right places and things like that I soon realised that the speakers I were using in now way suitable to check the sound and also my test bench monitors seem to be getting really picky about what they display properly.
In the end I settled for a black and white picture but I wasn’t too worried as the fault I was looking for was audio related.

The fault was that in game the music didn’t play and the engine tone played at a constant tone.
With my almost useless setup I could hear exactly this. I did a quick heat check with my finger on the audio PCB to check if any of the chips were getting hot and to my surprise all the sounds and music came back when I prodded the M6295.

I powered down and reflowed the chip and all was working again.
I soak tested it as best I could and called it a day.

Muddymusic has now got it back and has confirmed the sounds and music are now good.

Dec 142014

Got a Jaguar console for cheap as I originally wanted the cartridge slot but like so many of my idea’s like that I ended up repairing it and not wanting to harvest parts from it.

This was sold as not powering up. Its important to know from the start that the Jaguar will not power on without a cartridge inserted but in this case it made no difference.
Opening it up and removing the metal shield allowed me to see the problem straight away and it is apparently a relatively common fault.

The voltage regulator IC has blown.
I ordered a new one and fitted it and now it at least powers up.

I haven’t really been able to test it yet as I don’t have a Jaguar AV cable. Also this version of Jaguar didn’t have an RF modulator fitted as it was the French ‘Peritel’ version.
Ill tap the signals some day and properly test this thing out so if it doesn’t work then it looks like ill have my cartridge slot after all.

Atari ST disk TOS

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Jul 022011

My mate Sophie wanted some EPROMs burning of the early TOS version for the Atari ST.
This version boots TOS from a disk rather than being “on-chip”.
I was given a couple of links to atari-forum.com and read how others had done it.
Because the ROM dump is only 16k and we want it on a 27c256 EPROM, we have to byte split the file into HI and LO and copy each file into itself 4 times.
Using the Windows command prompt you can type:
“copy /b disktos.lo+disktos.lo+disktos.lo+disktos.lo disktos256.lo”, and same goes for the HI file.

I originally tried this out on my STe and set the jumpers accordingly which allegedly allow a 27c256 eprom to be used but this now seems incorrect.
To throw me further in confusion, one of the EPROMs must have died somewhere between my house and my mates because it didnt work.

Feeling a bit deflated I sent an email off to user 1632 who originally started the post, asking if he could send me his files. He very kindly dumped his eproms and sent me them but they matched the ones I originally created.
All I could think of doing was burning them again and sending them off. This time they worked so a dodgy EPROM was the cause all along.

You can find the original forum post here


Thanks go to Mike (1632) for his help with this. I would have spent a lot of time looking in the wrong place without his help.