Millipede Issues

DackR

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Donor 2012
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The previous owner of my Millipede had the flyback go up in flames on him. I was told the game was working, but had my doubts. I finally had some time to install a new flyback today.

Here's what is happening:
ImageUploadedByTapatalk1357099185.233623.jpg
(I know the monitor needs adjusted.)

Sometimes the game shows garbled sprites, but always freezes. It plays a few sound effects while it starts up and then makes a loud humming noise.

Note that the only thing missing inside the cabinet that i know of are the coin mechs. Here are some more pictures.

ImageUploadedByTapatalk1357099712.145795.jpg

Note that the cables on this next pic were disconnected when I got it. Not sure if the red connector needs to be plugged in somewhere?
ImageUploadedByTapatalk1357099806.447032.jpg

Any suggestions are appreciated.
 
Note that the cables on this next pic were disconnected when I got it. Not sure if the red connector needs to be plugged in somewhere?

More than likely. Did you check the wiring interconnect diagram to see where it is supposed to go?

Any suggestions are appreciated.

* Search the forum for centipede/millipede troubleshooting.
* Test all the voltages going to the PCB.
* Verify the ROMs (pull them, dump the code, compare to known good binary dumps).
* Re-seat any ICs in sockets.
 
I believe the red connector is in the video harness. If so it is an extra plug. I was told that during production Atari was using several different monitors so they put multiple video signal plugs in the harness so they could use whatever monitor type they had at the time. Yours looks like a board problem, put it in test mode see if it gives you anything. Start doing the normal board test procedures, voltages, edge connector, ...
 
Matthew180 and jbk,

Thanks for the suggestions. I really appreciate it. I'll try some of this tonight and let you know what I find.

I think jbk is right about the red connector. I wasn't able to find a spot for it, and the monitor shows a picture without it, so it's probably just an alternate pin-out for a different monitor.

I don't have the schematics for the motherboard, or a manual. I will look for some when I get a spare moment. What equipment could I use to dump the roms? :) would a braze multi-pede kit possibly fix this if it turns out to be a rom issue?
 
Wow, I'm surprised a manufacturer would include an extra connector like that out of convenience. Connectors cost money. I would still trace it back to see where it originates.

You can *probably* (I have not looked) get the schematics from the arcade-museum page for millipede, or a quick Google search should produce some results as well. I have read that centipede and millipede are very similar (same board maybe).

As for testing the ROMs, you need (using the general term) an EPROM Programmer. These usually do more than just read/program EPROMs though. They can be pricey and hard to swallow the cost of getting one, but if you are going to own/maintain your own coin-ops, IMO it is a necessary piece of equipment. The original EPROMs are old and they can lose their bits (usually call "bit rot") over the years. If the code/data in the EPROMs is bad, then the game will never work correctly (obviously), and you need to determine if you are dealing with a software or hardware problem.

The other thing a decent EPROM programmer can do it test SRAM devices and TTL logic ICs, which can come in very handy.

In the order of highest to lowest failure, my personal experience is: Batteries, Electrolytic Caps, EPROMs, RAM (static and dynamic), CPU or other larger multifunction ICs, TTL logic.
 
If you look at the red connector it is looped back into the the white connector on the monitor.
 
I only had time to test the voltages and reseat a few of the roms on the board tonight. Only a couple voltages were slightly off, but I'm doubting it would be much of an issue. Or would it be? Any thoughts? How difficult is it to adjust the power supply on this game? ;)

Listed, actual
+5v = +5.07v
+10.3v = +9.85v
-22v = -24.48v
+15v = +15.2v
+22v = +23.5v
-28v = -27.5v

Thanks guys!
 
Do you hear any beeps? Millipede first tests RAM with beep codes. if your hearing actual game sounds... that would be weird.

One thing you can do is pull off the pokeys (carefully) and reboot.
and see how the self test proceeds. The pokeys are nice to have in because they help you with the self testing by allowing the beeps. but they also can cause weirdness when they are not working even though the self test is supposed to account for bad pokeys, I've reparied a few centipedes where everything but the pokeys were OK but the game was all garbage with them in.

when powered on
millipede will first test the RAMs and make beep codes (if the pokeys and sounds circuit is working) to tell you if the RAM is OK. If there is a ram error you'll also probably see the screen fill with mushrooms to some point while it beeps. you can actually tell what video RAMS are bad based on the number of mushrooms drawn to the screen if your sounds isn't working.

if the RAMs are ok, it will do a ROM check and display a code if a ROM is bad (assuming the video circuitry is working).
the test code is all stored on a single ROM so only that ROM has to be good for the test to complete (assuming everything else is working)

Assuming your power is good, more than likely you have a either
1) a problem with the crystal oscillator
2) a with address decoding circuits or data buffers.




i

if you cannot figure get it working on your own, I repair millipede boards for a reasonable cost.

-brian
 
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Millipede always checks at least ram at boot regardless of whether it is in self test mode or not (centipede requires the self test to be active for any tests) I cannot remember if it tests roms or if you need to do the self test switch to perform that test. Either way it's a good idea to turn on the self test to get the full test behavior. More than likely though based on the description I doubt the self test will do anything. Sounds like the CPU is not executing any code sucessfully



It's probably worth noting that Millipede only does the RAM/beep test if you have the DIP switch set to test mode. If I recall correctly..
 
Definitely looks like a board issue. Do you know anyone close with a Millipede that you can test it in? Definitely perform the self test in the manual. And yes the red connector is for a different monitor. Mine has a G07 instead of the MatsuSHITa and it uses that connector.
 
Thanks guys!

I'll try some more tests next time I can get to it. It's been a busy week and I've only been able to get out to the garage to look at it twice.

I'll definitely try some more tests tomorrow night.

Oh- almost forgot, last time I turned it on, the game was cycling through random letters and the mushroom sprites. It also played a short musical tune which I did not recognize. Weird, huh? No distinguishable beep codes that I know of.

Brzezicki, how do I go about testing the crystal oscillator? I have a pretty okay multimeter with some frequency checking functions. Would that do it? I've not done testing for that kind of thing recently. ;) just trying to get my game plan in order for attacking this tomorrow night. I also want to install a cap kit in the Matsushita tomorrow night along with a flyback and cap kit in a dk Sanyo I bought off the same guy I got the millipede from.

Airlair, I don't know of anyone near me with a cab I can test this in. Thanks for confirming my monitor wiring situation.
 
can you send a quick video of what it's doing. if it's actually cycling and repeating a of displaying and erasing the mushrooms and letters in a predictable loop or pattern that actually says quite a bit. If it's doing that, then the crystal is fine and that there's probably a memory error specifically in the 2101s or related circuitry. If your actually seeing mushrooms written to the screen (they generally go up once column of the screen then the next etc (though it happens fast) the memory error is specifically in the being in the video RAM (the 2101 RAMS or the related circuitry) as millipede tests the "work RAM" before it displays any mushrooms. You can even narrow down the which set of 2101s by disabling the watchdog and counting the number of mushrooms successfully drawn on the screen. (each "column" has 32 mushrooms, and every 16 mushrooms drawn are a different set of 2 2101s)

if it's not doing that the easiest way to test the crystal is with a logic probe or an oscilloscope. I don't know of any multimeter that can check or time a signal (not that I know alotof multimeters, but I have a pretty full featured fluke multimeter and it doesn't even do that). A lot have frequency read outs for measuring AC frequency, but that's different that what your looking for.



Oh- almost forgot, last time I turned it on, the game was cycling through random letters and the mushroom sprites. It also played a short musical tune which I did not recognize. Weird, huh? No distinguishable beep codes that I know of.

Brzezicki, how do I go about testing the crystal oscillator? I have a pretty okay multimeter with some frequency checking functions. Would that do it? I've not done testing for that kind of thing recently.
 
if it's not doing that the easiest way to test the crystal is with a logic probe or an oscilloscope. I don't know of any multimeter that can check or time a signal (not that I know alotof multimeters, but I have a pretty full featured fluke multimeter and it doesn't even do that). A lot have frequency read outs for measuring AC frequency, but that's different that what your looking for.

Ah! Now I remember why I have that logic probe. Lol I actually found it along with a box of parts that i haven't seen in 10 years. Haven't used it since high school. :( I know it's got red and black alligator clips and there is a sharp probe on the other end.

I'll make a video tomorrow night and upload it ASAP. It hasn't been very consistent that I can tell. It seems to make different noises and display slightly different images every time it is started. Thanks for helping.
 
Great then just probe pin 37 on the 6502 processor (right side 4 from the top)
If it flips state steadily it's ok. If it does not flip state or for some reason is erratic... The clock is not working.though based on the behavior your describing it sounds like that it is working.
 
Great then just probe pin 37 on the 6502 processor (right side 4 from the top)
If it flips state steadily it's ok. If it does not flip state or for some reason is erratic... The clock is not working.though based on the behavior your describing it sounds like that it is working.

I tried the logic probe and it reads a steady low, but flickered high on that pin. I don't think this probe is very good quality, so it may not be very accurate. Here is a video of the game in test mode.

http://m.youtube.com/watch?v=KD1P7-PgLEE

I was also wondering if anyone knows what could be causing the horizontal scrolling black bar? I've installed a new flyback and cap kit. The jail bars in the video go away with adjustments, but not this.

Thanks for all the help guys.
 
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Wow being that its playing puzzle bobble music I'd say its possessed by some type of arcade daemon ;)

Seriously though the pcb probably needs repair. It looks like it probably has serious errors in the memory circuits both the CPU Memory interface as well as memory video circuits. That's just my guess based on your video.

Did you try removing the pokeys by the way? And see what happens when it boots?
I'd try that first just to see how that effects things. I have seen pokeys cause strange conditions that don't make sense.. Somewhat like what your experiencing.

Also did that board previously work at some point? Or was it always bad?
 
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