Rabbit Punch PCB Problem
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mastercello
- Posts: 353
- Joined: Thu Mar 15, 2007 12:24 pm
- Location: Switzerland
Rabbit Punch PCB Problem
Got a Rabbit Punch PCB of ebay, seller sold as working board.
Unfortunatly i got it in the following state:
- All moving sprites are the same, changing the type of the object constantly.
- Background is perfect, also the bullets are shown normal.
Here are a few pictures of it:
What i've done already:
- Checked voltages, all fine with +5 and +12V
- Cleaned up the boards (2 Layer pcb)
- Reseated all socket EROMS and cleaned the sockets
- Reseated the connections between the boards
- Checked for bent pins
- Checked for visual cuted pins
When i run my fingers around two of the RAM IC's (HD74LS273) the pattern is stop moving from one to another object and stays in the same object.
Do i have a bad RAM?
How can i check this?
Do i have another problem?
Thanks for any advices
Unfortunatly i got it in the following state:
- All moving sprites are the same, changing the type of the object constantly.
- Background is perfect, also the bullets are shown normal.
Here are a few pictures of it:
What i've done already:
- Checked voltages, all fine with +5 and +12V
- Cleaned up the boards (2 Layer pcb)
- Reseated all socket EROMS and cleaned the sockets
- Reseated the connections between the boards
- Checked for bent pins
- Checked for visual cuted pins
When i run my fingers around two of the RAM IC's (HD74LS273) the pattern is stop moving from one to another object and stays in the same object.
Do i have a bad RAM?
How can i check this?
Do i have another problem?
Thanks for any advices
Is the RAM socketed ? If so try swapping them around to see if the behaviour changes.
It looks like you have a logic problem i.e. your address decoding might be broken. This problem is normally releated to PAL/GAL but you might also need to check the TTL logic connected to the PAL/GALs.
rtw
It looks like you have a logic problem i.e. your address decoding might be broken. This problem is normally releated to PAL/GAL but you might also need to check the TTL logic connected to the PAL/GALs.
rtw
http://world-of-arcades.net
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The future of ST-V rests upon our work and your work
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mastercello
- Posts: 353
- Joined: Thu Mar 15, 2007 12:24 pm
- Location: Switzerland
Unfortunatly the RAM are soldered, so not easy to change them around.rtw wrote:Is the RAM socketed ? If so try swapping them around to see if the behaviour changes.
It looks like you have a logic problem i.e. your address decoding might be broken. This problem is normally releated to PAL/GAL but you might also need to check the TTL logic connected to the PAL/GALs.
rtw
Here is the pdf maunal of the game, wich include 6 pages of schematics of the game.
http://www.masto.ch/egret/pdf/rabbitpunch.pdf
Would be nice if you could point me in some direction rtw.
Thanks in advance
I'm sorry but this is not a trivial issue The schematics are a bit vague and it's hard to make out the logic. What happens if you enter setup mode ?mastercello wrote:Would be nice if you could point me in some direction rtw.
rtw
http://world-of-arcades.net
The future of ST-V rests upon our work and your work
The future of ST-V rests upon our work and your work
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mastercello
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- Joined: Thu Mar 15, 2007 12:24 pm
- Location: Switzerland
Check page 18 in the PDFmastercello wrote:There is no setup mode at all.
rtw
http://world-of-arcades.net
The future of ST-V rests upon our work and your work
The future of ST-V rests upon our work and your work
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mastercello
- Posts: 353
- Joined: Thu Mar 15, 2007 12:24 pm
- Location: Switzerland
Sorry, i was not reading it right.rtw wrote: Check page 18 in the PDF
rtw
All fine in test mode, there is just one page were you can see the dip switch settings. Another were you can test all the inputs and the last one wer you can switch through the sound register.
Everything is fine in this three test modes.
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mastercello
- Posts: 353
- Joined: Thu Mar 15, 2007 12:24 pm
- Location: Switzerland
Thanks boys, he put a claim for the parcel already.sven666 wrote:..and then buy a new board off meJockel wrote:There is at least a partial solution.
Beat the ebay-seller to death with a blunt object.
(And claim your money back)
So i might get back the money, but the game still will not work.
@sven666 - do you have a Rabbit Punch for sale?
If you're up for a learning experience, try this:
Locate the RAM chips on the schematics, they're probably sprite ram given what happens. The fact that they're changing constantly and stop when you interfere with the chip, probably means one of the address or I/O lines are floating. For an interesting test, put your finger in the place that stops the cycling and power the game up just to see if there are any differences.
Really you need a logic probe for this, you need to test each leg of the affected RAM chip, to see which one(s) aren't pulsing as you'd expect. As a rule of thumb, anything which is connected (which will probably be every leg on the RAM) which isn't showing high/low or a pulse, can be considered a floating input or output. If the leg is an address line, then usually it's the chip connected to it at fault. If it's I/O, then it could be the RAM or the chip connected. Either way, replace the relevant chip(s).
If you don't have a logic probe, try to work out as best you can which legs on the chip have the effect of stopping the sprite cycling, it should be fairly easy to identify which chips are possibly bad.
This may not fix the game of course, I'm self taught but it's where I'd start personally.
Edit: by the way, the LS273 is not a RAM chip Sorry I didn't read more closely to begin with. You'll probably find it's connected to some RAM or ROM chips though, similar theories to above apply.
Locate the RAM chips on the schematics, they're probably sprite ram given what happens. The fact that they're changing constantly and stop when you interfere with the chip, probably means one of the address or I/O lines are floating. For an interesting test, put your finger in the place that stops the cycling and power the game up just to see if there are any differences.
Really you need a logic probe for this, you need to test each leg of the affected RAM chip, to see which one(s) aren't pulsing as you'd expect. As a rule of thumb, anything which is connected (which will probably be every leg on the RAM) which isn't showing high/low or a pulse, can be considered a floating input or output. If the leg is an address line, then usually it's the chip connected to it at fault. If it's I/O, then it could be the RAM or the chip connected. Either way, replace the relevant chip(s).
If you don't have a logic probe, try to work out as best you can which legs on the chip have the effect of stopping the sprite cycling, it should be fairly easy to identify which chips are possibly bad.
This may not fix the game of course, I'm self taught but it's where I'd start personally.
Edit: by the way, the LS273 is not a RAM chip Sorry I didn't read more closely to begin with. You'll probably find it's connected to some RAM or ROM chips though, similar theories to above apply.
System11's random blog, with things - and stuff!
http://blog.system11.org
http://blog.system11.org
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mastercello
- Posts: 353
- Joined: Thu Mar 15, 2007 12:24 pm
- Location: Switzerland
Yup - they're often a source of simple PCB faults, I had -three- bad ones in a chain on a Psycho Soldier board a while ago.mastercello wrote:LS273 is some kind of Flipflop Chip.
System11's random blog, with things - and stuff!
http://blog.system11.org
http://blog.system11.org