Pole Position RAM06 and a bunch of zeros

jacklick

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Just wanted to check if this looked right. Ram6 is 7J but don't trust how it is being displayed. I was getting weird characters initially and then reseated the interboard connector and pressed on all socketed chips then got this.


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Went ahead and socketed 7J and replaced with known working 2148sram and got the same behavior. Tried the removed suspect sram with my working cpu board and it works, goes to test mode with no errors. So something else going on on suspect cpu board.
 
watched ian's video here which should help focus on the first few areas to check. There was some prior acid damage that I am not sure was ever addressed thoroughly. I cleaned it up and socketed/replaced ls161 at 6a just to be sure it wasn't the issue.

Just got it set up on the bench with power and video so can easily start probing. I guess more reading and probing.

 
I haven't continuity checked everything in the area but when I socketed the 2148s I did check those lines. Will continue to investigate possible trace damage but the board looks good in this area.

I have swapped the following into my working board and they all work fine there. roms 7H&7F, 6116 RAM 7E, Custom @ 8H, and both 2148s 7J & 7K. Vice Versa, those to non-working board usually produce the same RAM06 error.

I was led down a path thinking it was rom in 7F as the behavior changed (random changing characters like it is making further through initial self-test) on swap out but maybe the socket isn't great or something else caused that or it wasn't making it as far...hard to tell.

Also piggy backed some LS157s at 6k and 6j with no change/impact. might try to piggy back some LS367 at 6F and then really try to understand the schematic on what lines are doing what.

I all that fails, I have a working board and busted out my sig2 analyzer. I think if I make a NOOP adapter for the z80, I will be able to measure some good signatures from the good board and compare, trace what is going.

Anyone know if atari published signatures for pole position as I think the KK sig2 and catbox sigs are the same?
 
actually Ian, if you built these noop adapters, I would buy some for the z80, 6502, etc. I am lazy and like having things clean not with a bunch of wires and pins bent out etc.

https://www.lo-tech.co.uk/wiki/Lo-tech_Z80_CPU_Test_Adapter

I picked up one of these z80 nop adapters but would have been probably better of building one myself or studying it a bit more first.

Below are the questions I asked the seller. It appears maybe the board will successful test a z80 but is likely not a true nop adapter. So I can't recommend nor use this adapter quite yet. Will post follow-up though.

1) the Data lines need to be tied Low (to Gnd) but by default are not on the adapter. Is it expected to wire them to gnd pin29 with manual jumpers or leave them floating/disconnected?
2) Not sure what C1 is used for or what its value should be.
3) Wiki doesn't state what the positions of RN1 are used for. I assume just easy test points of data lines once they are jumpered through to board?
4) according to my sig analyzer z80 nop fixture drawing, BUSRQ(p25), NMI (p17), and INT(p16) all should be tied to +5 but they go straight through to board under test.

Z80-Test-Socket-r01-Top.png
 
i have built NOP fixtures for both the 6502 & 6800 mpus and tied the data lines with wire to the ground pin, your diagram shows which pins are to be tied on the Z80 and where each goes so go with what it shows - and btw thats one nice diagram too, thanks for posting it


found this ...... http://www.ostermayer.ch/fehlersuche.html
 
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1) the Data lines need to be tied Low (to Gnd) but by default are not on the adapter. Is it expected to wire them to gnd pin29 with manual jumpers or leave them floating/disconnected?
3) Wiki doesn't state what the positions of RN1 are used for. I assume just easy test points of data lines once they are jumpered through to board?
That's what RN1 is for... pulldowns for the data lines. Jumpers connect them to the data lines on the board instead.

2) Not sure what C1 is used for or what its value should be.
Decoupling cap... 0.1u or nothing.

4) according to my sig analyzer z80 nop fixture drawing, BUSRQ(p25), NMI (p17), and INT(p16) all should be tied to +5 but they go straight through to board under test.
None of those should be firing when the board's not actually running code.
 
That's what RN1 is for... pulldowns for the data lines. Jumpers connect them to the data lines on the board instead.


Decoupling cap... 0.1u or nothing.


None of those should be firing when the board's not actually running code.

Thanks Mark! It does show the data lines are connected to the pins above RN1, which I can tie together and jumper to RN1 to gnd them. I was just expecting them to be gnd'd to start but then I guess the jumpers to pass them through to board under test wouldn't work.

So I guess I will give it a shot and see how it reads and signatures I get.
 
I did assemble this adapter. FWIW. Might get around to using it this weekend.
 

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Actually creepykenny (via pm) and Mark made a good observation which I obviously didn't understand 100%.

So have to put in my words and then have someone correct me or elaborate. RN1 column is for the pull down of the data lines to gnd. The link creepykenny referenced showed 8 470 ohm resistors. Not sure why the 470 values were used but believe a part like this might work for this application.

http://www.mouser.com/ProductDetail/Bourns/4609X-101-471LF


>>edit>> I obviously don't know jack about electronics but happy to read, self educate, and thankfully get some pointers from you all.
pull-up/down resistors
https://learn.sparkfun.com/tutorials/pull-up-resistors
decoupling capacitors
https://learn.sparkfun.com/tutorials/capacitors/application-examples
 
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....
Decoupling cap... 0.1u or nothing.
.....

Just seeing if I am further understanding this. Would the decoupling cap be used/required if you want to power the adapter without inserting into board/device under test or in case maybe the DUT doesn't have them? You say "or nothing" because it is likely the DUT already has them so likely not a big deal.
 
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Actually creepykenny (via pm) and Mark made a good observation which I obviously didn't understand 100%.

So have to put in my words and then have someone correct me or elaborate. RN1 column is for the pull down of the data lines to gnd. The link creepykenny referenced showed 8 470 ohm resistors. Not sure why the 470 values were used but believe a part like this might work for this application.

http://www.mouser.com/ProductDetail/Bourns/4609X-101-471LF


>>edit>> I obviously don't know jack about electronics but happy to read, self educate, and thankfully get some pointers from you all.
pull-up/down resistors
https://learn.sparkfun.com/tutorials/pull-up-resistors
decoupling capacitors
https://learn.sparkfun.com/tutorials/capacitors/application-examples

thanks creepykenny for the RN. Still haven't had time to actually use it and test signatures but soon hopefully!

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did you happen to check that PAL/GAL (whatever it is) just under the CPU? 7C I think? I had two fail on recent Pole boards that I fixed.
 
This is why I need to document here, I started on this cpu board again yesterday and basically went right back to square 1 of testing ram in another cpu board before thinking to reread my own thread.

So no, i haven't tested the pal chip. I need a 20pin .3 socket (only have 22). Also, haven't dived deep into the schematic yet but enough to know the z80 is the sound processor and the memory in question is sound memory. Going to print these out and go from there.
 

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in my experience with this error it can be any of the traces around the battery section, that PAL and the CPU IC. Obviously the RAM could be bad but thats easy to rule out. Also, bad sockets.
 
in my experience with this error it can be any of the traces around the battery section, that PAL and the CPU IC. Obviously the RAM could be bad but thats easy to rule out. Also, bad sockets.

Ram is ruled out and same with ram socket. Although I will triple check my work. Here is a pic of the battery section. I probably have checked this area in the past but will do again.
 

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