Defender weirdness

LyonsArcade

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Hello;
I'm working on a Defender for a guy, and i'm getting a rug pattern at boot up. He had somebody else work on it, and one of the decoder roms had a broken leg, and a cap had been broken next to the other decoder rom, so I repaired that stuff. I checked all my roms, everything seems good, sockets all meter out good, so I was looking around on here, lots of suggestions on checking the power supply.

This cabinet has a switching power supply installed, a pretty hefty one that isn't adjustable, it's the big silverbox kind, and looks like a kit somebody ordered from somewhere, because it has pinned connectors for the (three?) boards that get power from it.

Here's the strange part, when I check the voltages at the cpu's pins (which have been replaced) I get all the correct voltages.

Measuring at the RAM, though, I get craaaaaazy voltages. For example, using the battery holder as the "Negative" post, I get -1.4v at pin 1, 5.1v at pin 8, 5.1v at pin9, and nothing (shorted to ground I suppose?) at pin 16.

Uhh.... help?!
 
The RAM is 4864's, so maybe I'm looking at a pcb that's been upgraded, and had the -5 disabled? I'm getting like -1.5 or so at pin 1. Also I'm not getting my 12v at pin 8, i'm getting 5.1, I just rechecked to make sure.


EDIT: Just checked how to mod the power supply connector for this, and apparently the voltages are o.k. for the 4164's. On one hand I'm relieved, on the other hand the board don't work, lol.

What should I check next, folks? Should I try to just replace all the ram, the guy had a whole bag of 4164's.
 
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The RAM is 4864's, so maybe I'm looking at a pcb that's been upgraded, and had the -5 disabled? I'm getting like -1.5 or so at pin 1. Also I'm not getting my 12v at pin 8, i'm getting 5.1, I just rechecked to make sure.


EDIT: Just checked how to mod the power supply connector for this, and apparently the voltages are o.k. for the 4164's. On one hand I'm relieved, on the other hand the board don't work, lol.

What should I check next, folks? Should I try to just replace all the ram, the guy had a whole bag of 4164's.

Ouch!

So the reason you are getting -1.5 is that the 4164 do NOT require -5 nor do they require 12V. Just the +5V.

You have a board with fried 4164 RAM.

Either: A, replace the ram with all 4116 RAM

OR B, do the power mod for 4164 and replace the fried 4164 RAM with good 4164 RAM.

Just my $0.02 worth,

Saltbreez
 
Ok, this may sound a bit wonky....
But I start with ram chips that either feel "dead cold" or "extremely hot". Hopefully if it's a bad ram issues that may be enough to get further along and actually get errors coming up if there are more bad ones.

Last one I had that didn't make it past the rug pattern was due to bad ram, lots of them....power supply went south and cooked nearly half the ram.
Generally I take all the "suspect" ram and set it aside and once things are up and running double check each one at a time so it'll pop a specific location error.
 
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Ouch!

So the reason you are getting -1.5 is that the 4164 do NOT require -5 nor do they require 12V. Just the +5V.

You have a board with fried 4164 RAM.

Either: A, replace the ram with all 4116 RAM

OR B, do the power mod for 4164 and replace the fried 4164 RAM with good 4164 RAM.

Just my $0.02 worth,

Saltbreez

Thank you for your .02, but the board has had the power mod, that's why there's no -5 and no 12v. If I replaced them all with 4116 ram, I think i'd fry all that!
 
Ok, this may sound a bit wonky....
But I start with ram chips that either feel "dead cold" or "extremely hot". Hopefully if it's a bad ram issues that may be enough to get further along and actually get errors coming up if there are more bad ones.

Last one I had that didn't make it past the rug pattern was due to bad ram, lots of them....power supply went south and cooked nearly half the ram.
Generally I take all the "suspect" ram and set it aside and once things are up and running double check each one at a time so it'll pop a specific location error.

I understand completely what you're saying about the cold/hot, a working chip should be kind of warm I guess and if it's dead cold it's probably shorted open and if it's hot it's probably shorted closed! I'll try that out, the guy brought it to me with a whole bag of ram, somebody ordered a bunch for him but never got around to switching them out or something.

Also, the 3E? rom had a broken leg, and was a new chip they got about 6 months ago from hobbyroms. It had a paper sticker on it, that was really charred up, already. Does that chip usually run hot? I was able to solder another leg back on it, but I haven't been able to check that rom chip because I don't know what I can check it as in my pocket programmer. It's a 74series rom, I've never seen one.
 
Oh, so it has this piece of crap in it?

!BS8UW!!B2k~$(KGrHgoOKisEjlLl5Pu2BKF)Srz!B!~~_12.JPG


http://forums.arcade-museum.com/showthread.php?t=126239
 
Also, the 3E? rom had a broken leg, and was a new chip they got about 6 months ago from hobbyroms. It had a paper sticker on it, that was really charred up, already. Does that chip usually run hot? I was able to solder another leg back on it, but I haven't been able to check that rom chip because I don't know what I can check it as in my pocket programmer. It's a 74series rom, I've never seen one.

3E is one of the Decoder Proms, along with 3K. They were originally 7641 Proms, and they're hard to find and most eprom programmers can't write them. But you can substitute a 2716 or 2732 if you bend/cut a couple of pins and solder in a jumper wire (on the chip). Normally I'd use this link to explain it:
http://www.arcadesolution.com/decoder2.html
but for some reason the site is down??? Bob Roberts also has an explanation:
http://www.therealbobroberts.net/decoder.html
I've used 2716's as decoders, but in my experience the chip needs to be 350ns or faster - the faster the better. You can get the code for the eprom from Mame.
 
D it's not exactly like that, but very similar. It's a square box, like your typical 250amp/350amp power supply you'd see in a "NFL BLITZ" or something, and has green, white, black, red, and one white with black stripe lines coming out of it. It has three connectors like yours there but not labeled, just sharpied "CPU" "ROM" "SOUND". I would imagine the same place probably made them.
 
3E is one of the Decoder Proms, along with 3K. They were originally 7641 Proms, and they're hard to find and most eprom programmers can't write them. But you can substitute a 2716 or 2732 if you bend/cut a couple of pins and solder in a jumper wire (on the chip). Normally I'd use this link to explain it:
http://www.arcadesolution.com/decoder2.html
but for some reason the site is down??? Bob Roberts also has an explanation:
http://www.therealbobroberts.net/decoder.html
I've used 2716's as decoders, but in my experience the chip needs to be 350ns or faster - the faster the better. You can get the code for the eprom from Mame.

Thank you for the info. Apparently the guy just had them burned about 6 months ago... so i'm leaning more towards it's the ram, although anything is possible I guess. The leg DID break off in the socket, but I think that may have had more to do with the j.a. he had working on the board before. Of course he could have also put the chip in backwards and fried it, so I don't know.

I was going to just try and read it, but like you said I don't think my programmer can support that chip. I've got the code.

Also the two original chips came with it, but they say Decoder 4 and Decoder 5. WTF? I thought it was supposed to be 2 and 3.
 
Also the two original chips came with it, but they say Decoder 4 and Decoder 5. WTF? I thought it was supposed to be 2 and 3.
I think Decoders 4 & 5 was an early Stargate thing before Stargate went to 4 & 6, but if the machine previously worked with those decoders then I wouldn't worry about what numbers they are. I've heard about a Defender running on 4 & 6, and I've had an upright work with 2 & 3 where they usually use 1 & 3. Decoders 2 & 3 was the cocktail setup:
http://arcadecontrols.com/BBBB/decode.html
 
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The thing is, I don't know the history of this board. They could have bought a stargate board and transplanted it into the cabinet, then replaced the roms. The gentleman that has the game doesn't know anything about them, he's had some guy half-ass working on it, so not only do I not know what he did, I can't trust anything he did either. These definately say 4&5, so I guess maybe it was an early stargate board. Board is clean, no acid damage and minimal work has been done to it.

I'm going to try running down some rams tommorow and see if that changes my image. I had a lot of straight lines, before I found the broken rom pin and the broken cap(the guy broke it prying one of the rom chips out!)... now I've got a more typical 'rug' pattern, lots of red and blue zigzag patterns on the screen.
 
Read out the model numbers off the boards and post them. Or post decent pictures. It sounds like somebody did a half assed RAM upgrade and then either swapped the wrong CPU board in or fried the decoders and swapped whatever was handy.

Stargate CPU will be model 5770-09656-00 (it will be above the battery holder)
Defender will be 5770-09616-X0 (it will be in the upper left corner next to the ROM connector)

ken
 
Alright, I took some pictures. The board say s09616-01 up near the rom connector. The serial number tag was over this, so I took it off, but the serial number didn't match the other boards so it's at least been swapped.

Here's a picture of the rug as well, I think i'm going to start testing those RAM for heat, maybe repace a row at a time.
 

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The board is definitely a Defender, but what you have on the screen isn't a normal rug pattern. Here's what the rug pattern looks like:
 

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I found a problem, they have MOST of the chips as 4864, but some of them are 416c's. So I'm going to remove the 416's and install the rest of the 4864's.
 
I put the guys hand full of 4864's back in, so now all the chips are 4864's. It's booting to a slightly different pattern now, but still not the correct one. I'm thinking he's probably still got bad ram, and maybe even those decoder chips are bad.
 
I put the guys hand full of 4864's back in, so now all the chips are 4864's. It's booting to a slightly different pattern now, but still not the correct one. I'm thinking he's probably still got bad ram, and maybe even those decoder chips are bad.

Actually, since it never got to the rug pattern, even the ROM board could be bad - and just because all the ROMs read okay doesn't mean the ROM board works. Do you hear any sounds when you power it up? Any LED's lit on the ROM board? Any chance you could get a known-working CPU or ROM board to test with?
 
When you see horizontal or vertical patterns occurring in the rug test, that is usually a good indication that there is a problem with the addressing circuits. The RAM may or may not be good (in fact if you had 4116 RAM chips left on the board, they are probably toast, the 4164 power supply adapter took care of that).

It is definitely a Defender board. The fact that you are seeing anything changing in the display when the RAM test runs is proof of that.

Drop Saltbreez a PM, maybe you can work out a deal with him on a new Defender motherboard. I'd offer you one of mine, but the only one I currently have that I would trust is scheduled for my Defender rebuild this summer.

ken
 
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