Bombjack ram location

[Retroman839]

Ok só I am getting a ram 2 error

Anyone know ram locations
For ram 0 1 2 3 &4?
Pls

I have 4 rams @ 4, abcd
Which one is ram 2?

 

[TheDaddy]

I cant look myself at minute as busy but the CPP may help here https://github.com/mamedev/mame/blob/master/src/mame/tecmo/bombjack.cpp

There is a lot of ram on these from memory both on top and bottom board.

Dave.

 

[Retroman839]

I cant look myself at minute as busy but the CPP may help here https://github.com/mamedev/mame/blob/master/src/mame/tecmo/bombjack.cpp

There is a lot of ram on these from memory both on top and bottom board.

Dave.

Hey Dave 👍
Cool will check it out thanks ..
Someone must have mapped it 😊

 

[TheDaddy]

You have slice now , so you can slice them maybe ?

Dave.

 

[Retroman839]

Yeh schimatic I have been reading it mentions U8
A lot which triggers sound as well as I have no sound I think U8 does colour pallet too ,
My problem is I don’t have U as a letter on my silk screening

 

[Retroman839]

You have slice now , so you can slice them maybe ?

Dave.

Been slicing and got some suspects ..
But I would love to know which rams are which 😊.

I will piggy back when they come but been advised I might blow good rams this way

 

[Jacmar]

https://www.thedefenderproject.com/other-arcade-games/bomb-jack-fix-logs-and-other-information/

Bunch of fix logs for Bomb Jack relating to RAM and TTL. Also some info at the very bottom of the page relating to RAM use and positions. Not RAM 2 though anyway hopefully some info there that can help?

 

[Retroman839]

https://www.thedefenderproject.com/other-arcade-games/bomb-jack-fix-logs-and-other-information/

Bunch of fix logs for Bomb Jack relating to RAM and TTL. Also some info at the very bottom of the page relating to RAM use and positions. Not RAM 2 though anyway hopefully some info there that can help?

Thank you man 👍will give this a look

 

[Retroman839]

Slice shows This ram has errors,
Ram next door to it passes all cycles @50 cycles
This ram fails on cycle 1!
Só seems bad .. just need to find a replacement now.

 

[Jacmar]

I wouldn't assume that chip is definitely faulty. Those are low error numbers, have you tried tweaking the propagation time up a little? might pass then...
(keep meaning to get a 24pin clip myself for those bigger IC's!)

 

[Retroman839]

https://www.thedefenderproject.com/other-arcade-games/bomb-jack-fix-logs-and-other-information/

Bunch of fix logs for Bomb Jack relating to RAM and TTL. Also some info at the very bottom of the page relating to RAM use and positions. Not RAM 2 though anyway hopefully some info there that can help?

Cheers jack

https://www.thedefenderproject.com/other-arcade-games/bomb-jack-fix-logs-and-other-information/

Bunch of fix logs for Bomb Jack relating to RAM and TTL. Also some info at the very bottom of the page relating to RAM use and positions. Not RAM 2 though anyway hopefully some info there that can help

I wouldn't assume that chip is definitely faulty. Those are low error numbers, have you tried tweaking the propagation time up a little? might pass then...
(keep meaning to get a 24pin clip myself for those bigger IC's!)

I will give it a go👍

 

[Retroman839]

When game is booting and is just going through ram rom check it passes it’s cycles .

As soon as the game begins the ram fails .

And it keeps failing ,
The other 2116 next to it always passes , só I would say if others pass no problem with the same test then this one is bad .

I have repeated the test 8 times with both rams and results are consistent,

I would be surprised if I don’t have some other 2114 Thats also playing up.
I have bought a replacement now Só can piggyback it ser if that changes anything

 

[Jacmar]

I've got loads of games with IC's on that fail slice test but work fine. Often it is contention on the bus or that the circuit doesn't like the extra loading slice puts on the pins. I've learned that very low number fails like yours (0-20) are usually not an issue, the chip either passes with increased prop time or just don't pass the slice test but work fine in the board.
But I've also spent hours with analysis paralysis looking at data and sometimes you've just got to get stuck in and swap things out

 

[Retroman839]

I've got loads of games with IC's on that fail slice test but work fine. Often it is contention on the bus or that the circuit doesn't like the extra loading slice puts on the pins. I've learned that very low number fails like yours (0-20) are usually not an issue, the chip either passes with increased prop time or just don't pass the slice test but work fine in the board.
But I've also spent hours with analysis paralysis looking at data and sometimes you've just got to get stuck in and swap things out

Yeh I hope piggy backing will show a sign of improvement on this 24 dip ram ..
I have a compatible in order Só hopefully it improves things ..
Then I will turn to the 2114’s

 

[Monstermug]

More often than not, ram do not die gracefully. Usually, faults will show up as intermittent lines, intermittent faults, etc. Most of the time simple ram checks wont be able to check ram completely. They just send a signal to the ram, then reads it and if its the same it passes. To completely check ram, you need to r/w to the entire ram which equipment like the fluke 9010a etc can do. I'm not even sure most chip testers can accurately test ram? As slice is only passive, it cannot write, just read the signals.

 

[GadgetFreak]

Ram 0 & 1 are lower & upper 1K of the same 2Kx8 ram chip @1E on the bottom board
Ram 2 & 3 are lower & upper 1K of the same 2Kx8 ram chip @1H on the bottom board
These are right next to the ribbon connectors next to the 5 maincpu eproms in a line.

 

[Retroman839]

Changed last night ram 2&3
No dice ,,

I’m starting to suspect a broken trace

 

[Retroman839]

2116’s

 

[Retroman839]

This is my pcb it was working ok 2 years ago last time I had it on,

Going to look closer tonight at a scratch I have found.



Mame source code mentioned
Right at the start ram @ u8 ?

I would love to know what u8 is ?

As I have no sound u8 handles colour pallet & triggers sound cpu.

I’m just assuming u8 is the ram 2 /3 as I’m getting fault here ,on power up & it’s next to the pallet sprite eproms

 

[GadgetFreak]

Changed last night ram 2&3
No dice ,,

I’m starting to suspect a broken trace

You have the Schematics I presume?
There isn't much between ram and cpu, and only a few chips handle the select for rom/ram/IO.
Unusually it uses a bunch of 74LS86's to handle address line buffering. These are @ 2J-2M, basically next row to program eproms.
74LS139 @ 3M, 74LS138 @ 4M & 5M handle main bulk of addressing.
74LS32 @ 7T & 3H, 74LS27 @ 1C handle some of the control lines.
74LS245 @ 2H sits on the data bus and 74LS20 @ 6N controls enable.
You should also be able to use the schematics and buzz the address/data lines with a meter to check for connection.
And of course Slice will identify any inputs that are floating using the Float test.