Centipede issues- ONGOING

[newkillergenius]

Hey team

so I've got this Centipede, it is possessed.

The original board screwed up on me.  Sound went out, all the shrooms were plastered to the left side of the screen, and the flea fell.  All the time. Constantly.

So.

I bought a new board.  Popped it in.  Game comes up!  Cones both blink!  everything is in it's right place.
I hit start- meh.  Sound is still missing- no wait- if I turn the pot ALL the way up, I can FAAAIIINTLY hear the game sound coming from the speaker.  And- it appears that no matter how many times you shoot the spider the bullets go right through!  
But shooting the centipede portions results in hits.  I'm looking hard for a solution.  This has been going on for over a year.

Is it the power block?

the AR II?

What could be going on here?  This went from a fully functioning machine to a soundless- screwed up trackball- and graphics POS almost overnight.
Now with the new board the gameplay seems almost 100% correct, but still no sound. (that you can hear at least, you have to have your ear IN the speaker....)

Here is a video of the machine the NIGHT BEFORE it took a dump and powered on to garbage.
*NOTE*  at the very end of the video someone utters the F.  Keep the speakers down if you're at the office.



See?  It was just fine!  No problems at all!  

PLZ!  Halp!  

[RayB]

I don't want to make you feel dumb or anything, but think about this:

The game is working then craps out on you. You replaced the main circuit board. Now let me ask you, did you bother measuring any voltages? Usually when something electrical fries, it's due to something else frying it. So, by popping in a replacement board, you've fried the replacement because you haven't looked into the cause of the problem in the first place.

OK, lecture over.

Yes it's most likely the AR-II needs repair. The AR-II regulates DC voltages AND is a sound amp. Also it's recommended to replace the giant capacitor if that hasn't been replaced in the last decade or so.

Also check the connectors for proper contact and clean the edge traces on the game board.

[newkillergenius]

Thanks for your reply Ray, and that doesn't make me feel stupid- in fact it is good advice, and others reading this thread may learn something- though few people here will be able to lecture me on vintage arcade machines and voltages.  Bet that.    I checked all this stuff long ago and it seemed fine, that's why I felt comfortable with putting the new board in in the first place.
I did in fact meter the power block, and did not see anything out of the ordinary.  What I did notice though, was some intermittent 'crackles' when checking the ARII board.  I have another one that was in a Pole Position, it seems like that will be my next move.  I did replace big blue as you suggest, still no go.

The replacement board is not fried, it works fine with the exception of the low audio and the spider anomaly.
This was not occurring before the old board was blown, and then *cough  stolen.  I have decided not to power the machine back on until a thorough examination of the 2nd ARII board has taken place.  Edge connections are A-OK.  

As far as the ARII is concerned, are you aware of any issue that might arise as a result of me using an ARII from PP instead of another Centipede?
I haven't done that particular swap before.

[RayB]

Sounds like your main issue is the AR-II, and then there might be damage to the game board. Familiarize yourself with Atari's AR-II first, and then you'll be half way to being an Atari coin op expert:

AR-II have a number on them, usually in black marker that says -02, or -03, or -04 etc. You must stick to the same version.

This page has links to a list of which games use which version. It also has a link to a page all about adjusting the AR-II : http://www.elektronforge.com/tech_help.htm

This page is on how to mod the AR-II so that it does not automatically adjust its own voltage levels. That sounds like smart engineering, but it leads to voltages pumping up too high when it "thinks" there's is a voltage issue and that leads to burnt edge traces, which leads to higher voltage due to bad contact, etc until finally the voltage is so high it damages the game board:

http://www.stickycarpet.com/pinx/ar2mods.html

You should be good to go after you sort out what you got. Finally, you can buy a rebuild kit from Bob Roberts: www.therealbobroberts.net

[newkillergenius]

Yeah, it's looking like there might be a few Moon Pies in my future.  Tried another Atari power block this morning but before attaching the PCB.  Voltages were all screwy.  So I think my original block is good, just have a bad ARII.   A friend had suggested that I use the ARII out of my old Pole Position but after thinking about it more, I think I'm just going to shoot Bob an email- because I am fairly certain they are not the same, though visually similar.

Thanks Ray for your time, I'll keep this thread posted and try to throw up some victory pics at some point!!!  

This is the Centipede ARII.  The one out of my machine looks a bit different.  Maybe someone has screwed this up long before I got it, and it was just a ticking time bomb for me.  Probably a fair assumption.

[RayB]

A friend had suggested that I use the ARII out of my old Pole Position but after thinking about it more, I think I'm just going to shoot Bob an email- because I am fairly certain they are not the same, though visually similar.

You didn't bother looking at the tech links I supplied? One of them shows exactly what AR-II's are compatible in what game. Centipede uses the -02 revision. Pole Position uses two -01 revisions. So no, they are not compatible.

[newkillergenius]

You didn't bother looking at the tech links I supplied?

Yes, actually- that photo I posted is from that website...