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Hi All, just relating an experience here

I had my Money Mad Martians on and playing most of the day yesterday and turned it off last night, everything fine. Turned it on this morning to a basically dead machine. All it had were the florescents  with the top two green LEDs and the red LED flasing on the MPU, wouldn't do ANYTHING else. I pulled the MPU and swapped the RAM chips with no success. Not to be discouraged I grabbed a set of RAM chips off a spare board and tried those. Had to do the mismatch reset, but it came up and worked, machine is fine. Now, I can't explain why the RAM seemed to go bad overnight or what may have caused it, but if anyone experiences this problem, here's a possible cause and solution

You must have pissed it off Rob.  Were you winning too much?

Jason

Actually it WAS a payin' son of a gun yesterday, you might be right :97- Only thing I did yesterday and this was like 5 hours before I shut it down for the night, was to put a new LED board in the denom window. It's a complete replacement for the incandecent board, but it worked fine for hours after the replacement

Now you have me wondering...do the old RAM chips work with another MPU cowboy?
Or are they kaput?

I'm not sure Bunker, haven't tried them in a differant board yet. All I know for positive is that swapping them in each others sockets, which is known to clear them, should be the same as changing them out and it didn't work. I'll try them in one of my other games and let you know, but to me it's kinda like sticking your finger in a light socket and hoping the switch is off. You're asking for trouble :89-

I agree cowboy but I change chips all the time trying different stuff.
I've stuck them in backwards and with certain legs bent on purpose to see what happens... :72-
Experimenting this way has never ruined any one of my 3 MPU boards ( 2 are 502's while the other is a 504)
but sometimes the chips got corrupted.  :47-
That's the result of screwing around with things trying to force the machine to produce errors -
in experimental simulation to member's errors they post up on various threads.
Not a problem when you have some blank eproms and a burner...that's why we back-up things.

Not having any here on-hand, ( going by photographic memory really) those RAMs in U-18 & U-45, what devices are they?
AMD27C801's or something else?
They have what appears to be a little IC flash memory on a green circuit board on top right?

They do and they say ADVANCED on one end of the chip and 4414-632 on the other end. I'm a bigger chicken than you though. I think Buzz is the one that says don't f$$k with it till you break it or something to that effect :97-

All i know is that they're 32-pin devices...
I'll look at mine tonight when I get home.
So swapping them top and bottom will wipe them out?  :79-
Hmm....I've never tried it yet.... :72-

Click on snapshot below to enlarge...>>>

I'm not sure it "clears" them, but it makes the machine ignore what's written on them because it screws up the file path. I did set them on a piece of metal before the third time I reseated them though. I guess this is also supposed to clear them

I'm not sure if that "clears" them cowboy but I'm sure they get corrupted! lol
The internal logic gates and Rows & Columns (RAS# & CAS#) of the eproms need certain voltages applied
to specific pin legs to make them all "0's" or "1's" - I don't know which number would make the chip cleared though.

I would tend to believe that grounding some of legs to metal sends electrostatic electricity
to the legs that contact and corrupt the hell out of a chips' written data.
That's the primary reason why eproms should be handled very carefully
and really should be installed using an ESD wrist strap -
Though, I don't think anyone actually has one or uses them.... :72-
I just keeping touching the metal part of a machine or the metal part of the tray...  :5-
The room where my slot is has plush carpeting and because of the high-level of winter-time static -
I'm shocking :50- the heck out of myself all the time... :96-

( BUNKER QUOTE )
I would tend to believe that grounding some of legs to metal sends electrostatic electricity
to the legs that contact and corrupt the hell out of a chips' written data.
That's the primary reason why eproms should be handled very carefully
and really should be installed using an ESD wrist strap -
Though, I don't think anyone actually has one or uses them.... :72-
I just keeping touching the metal part of a machine or the metal part of the tray...  :5-
The room where my slot is has plush carpeting and because of the high-level of winter-time static -
I'm shocking :50- the heck out of myself all the time... :96-
[/quote] BUNKER if your humidity level is low in the room static electric shock is common . As in   rubbing    shuffling    dragging    across  carpeted flooring  or petting cats and dogs and touching any metal surface in the dry room. Its the same way rubbing a balloon against hair will make the balloon magically stick to the wall  . Just add a humidifier in the room and it will go away  NO MORE SPARKY

The CMOS RAM chips are RAM, not any form of an EPROM (They are totally different)
that is why they need a battery to keep the data in them when the machine is off.

So I'm home now and first thing I did was switch the two chips in my 502 MPU at locations U-18 & U-45.
I got the "Call Attendant", opened the door and the horn sounded with the message "RAM ERROR"
I pressed the white Test button for about 3 seconds then closed the door - the game booted up and played like before.

I wasn't happy... :60- my machine saved itself & I didn't blow up anything...   :37-
So I removed the two chips again and threw in similar chips from an entirely different 504 MPU.
I got the "Call Attendant" message again, opened the door, got the horn & "RAM ERROR" message again,
pressed the TEST button for a few seconds, closed the door.
The machine again booted itself up into normal game mode.  :8-

I went into accounting, checked my settings and everything was normal.
Even my history was saved and meters still the same.
It was like as if my machine didn't even know I was screwing around with it!  :97-

I did the same thing when I used the RAM off one of my extra MPU boards. It is quite easy and painless that"s for sure :89- You get to keep all your settings because the memory for those is on the chip on the motherboard. The only thing you lose is accounting info as far as activity history and any credits that were on the machine when you changed the chips. The motherboard saves all user access programming settings. I'm not afraid swapping chips will damage it, I'm afraid every time you pull and mess with an MPU you're opening yourself up to potential damage. It's easier to beat the odds when you keep them in your favor :89-

I forgot to add this picture of the chips I took.
I flipped over the right one to show you guys what they look like underneath.
They're definitely NOT cased like normal eprom packages - look more like flash memory chips.

Click on photo to enlarge if desired...>>>

Bunker  Most but not all look like yours. Some look like regular chips.  If you recall you and I talked about them and you came up with a price of around $18 each for replacements.  HM628512BLP-7

They are M5408BFP-70 on my 504B
Oh by the way you cant pull them on the 1270
 Which are Static RAM chips, 4MBit (512Kx8)
Static RAM does not need a refreshing signal (basically a clock signal) to keep the data intact.
just some form of power either from the power supply or the CMOS RAM battery.

Where as our computers use Dynamic RAM, as far as I know DDR (2 and 3 included) are still some form of DRAM

Yeah...those suckers are hard to find.
I think I looked for them one time as Buzz said.
I believe mouser.com had them or Jameco.

HM628512B Series...>>>

http://melca.com.ar/HOJA%20DE%20DATOS/MEMORIAS/hm628512.pdf (http://melca.com.ar/HOJA%20DE%20DATOS/MEMORIAS/hm628512.pdf)

The BLP series on page 3.