Paperboy 6502 Processor error...

descrentl

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Ok, so Im in the process of trying to get my Paperboy up and running. After some power adjustments and reflowing joints, I get this error. Can anyone shed more light on it? I have swapped it with a known good 6502 and it didnt help. I tested the original in my 720 and it worked fine. Does wacky voltages affect this? Could it be a bad socket? Any help would be great. Thanks

pbtest.jpg
 
When testing, try and go back one solder point from the connector/joint so you know it's not the connector-board solder joint.
 
So heres what Ive done so far. Ive reflowed all the pins on the connectors. I metered the edge connector and none of the pins show open. My switcher and ARII are putting out proper voltages. I got my 5v on the test points on the boards. Now I cant get back into test mode. It just shows garbage. Does anyone know where to begin on what chips I should be checking for correct voltages? Any other areas on the board I can test? Any help would be great. Thanks
 
So heres what Ive done so far. Ive reflowed all the pins on the connectors. I metered the edge connector and none of the pins show open. My switcher and ARII are putting out proper voltages. I got my 5v on the test points on the boards. Now I cant get back into test mode. It just shows garbage. Does anyone know where to begin on what chips I should be checking for correct voltages? Any other areas on the board I can test? Any help would be great. Thanks

It is probably time for a logic probe.
First, check to make shure you are gettin' a clock signal to the chip. If the 6502 does not get a clock/crystal signal it will never start.
Other than that maybee wiggle and push on stuff (rom chips) THEN power back up. Also make try another ribbon cable just 4 fun.
?And maybee check ur dip switches...Happend to me once.
 
Yeh, when I did get into the test mode, the 6502 was failing. It doesnt have a ribbon cable to connect the 2 boards together. I swapped out a known good 6502 and it didnt help.
 
It is probably time for a logic probe.
First, check to make shure you are gettin' a clock signal to the chip. If the 6502 does not get a clock/crystal signal it will never start.
Other than that maybee wiggle and push on stuff (rom chips) THEN power back up. Also make try another ribbon cable just 4 fun.
?And maybee check ur dip switches...Happend to me once.

Did you check you crystal?
 
I dont own a logic probe. If I get my hands on one, where do I check to see if its working correctly?

I haven't woked with a 6502 for some time, since kim-1. I do know, from reading several posts here, that ALL CPU chips needs a signal or what is commonly refered to as a "clock" to even get started. Kind of like a starter on a car. My kim-1 had one. It would be x1/y1 or xtal on the pcb and without a logic probe you may see some small voltage changes. I would just ohm it to check the connections to cpu/6502. The voltage is very small and it is more of a pulse.
When I get a chance to look at schematic I will be able to tell you more.

It is usually a small tin colered can type thing with some kind of numbers on the top end.
 
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On page 6-42 of the atari book there is a good pic of the 6502. The clock signals I am talking about are on the upper right side in that pic.
 
A fellow KLOVer that lives real close has a logic probe so I will be checking it out soon. I want to play this so dam bad.
 
So today I swapped all the removable chips from my Paperboy CPU, to my 720 CPU, and it fired up with graphic glitches using the 720 graphics board. I think thats telling me that my CPU board is working, so now Im leaning towards it being a bad graphics board. Theres a ton of chips on the graphics board so I havent done that swap yet. Could a bad graphics board not let the game boot? I still need to get a logic probe and test the crystal.
 
When you do get your hands on a logic probe check the cpu lines. You can use a multi meter to see the voltage changes in a pinch.

nmi=6

irq=4

rdy=2

res=40

r/w=34
 
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