Midway clowns and 2716's

[jetusenet]

Quick update, my monitor crapped out and I am now in the process of the rebuild, once completed I'll get back to the boardset.....
Also took this time to touch up the cab, looking good!

 

[jetusenet]

Monitor rebuilt and looks kinda nice......

 

[jetusenet]

This is with the Test Rom installed:

Test ROM.mp4

Shared with Dropbox

www.dropbox.com

 

[jetusenet]

This is with No ROMs installed:

No ROM.mp4

Shared with Dropbox

www.dropbox.com

 

[jetusenet]

This is with the Program ROMs (3 X 2716's) installed

Game ROMs.mp4

Shared with Dropbox

www.dropbox.com

 

[jetusenet]

Next is troubleshooting the boardset......

 

[wugly]

Never seen something like that. The no roms proved that your board is capable of generating a proper formated image with monitor horizontal and verticle signals. Ram has a problem but you need to fix how data gets from rom to ram. Changing to test rom puts rom out of mix. It has lines so it did a cpu reset and run. Would look to see address lines active to rom and enable. Check data flow to cpu and rams and chip enable for the bidirectional data and mux chips. Last look Would be ram addressing

 

[wugly]

Cpu can update the ram since it is drawing lines. Unknown if data is getting to cpu or being corrupted going to cpu

 

[jetusenet]

Thank you for that guidance....

I'll be back on this tomorrow and will post the results.....

 

[jetusenet]

Well that was a long night!

Back to the board and I probed the CPU and the EPROM with my logic probe and one item that jumps out is that pin 19 of the EPROM (A10) is dead. Not Hi and not Lo just nothing. Is this normal?

Thanks

Jeff

 

[jetusenet]

....also pin 12 of the CPU (Reset) is LO and every few seconds I get a "blip"..... trying to reset?

 

[wugly]

pin 12 being low means it is trying to run. it operates in low signal th ehigh pulse is the reset pulse. a10 is a more complicated story that has 2 answers. pulse is the watchdog kicking in

 

[wugly]

A10 being disconnected on the rom chip is not correct. as you look at the schematic A10 on the chip does not in anyway connect to a10 from the cpu of any chip connected to it. pin 19 on the rom chip depending on the rom chip must be connected to either +5 volts or 12 volts (someone should double check me but I believe its 5 volts) A10 from cpu goes to E2 which gives the proper chip select signal

pin 19 labeled a10 is connected to 5 volts or 12 volts not cpu a10

 

[jetusenet]

This is the strapping I am using, can I get an Amen?

 

[philmurr]

This is the strapping I am using, can I get an Amen?

That strapping is for 2716's as per my earlier post. Aren't you using 2708's?

 

[wugly]

isn't your s3 one line too low?

 

[jetusenet]

On this thread there are 2 different strapping for the 2716

That strapping is for 2716's as per my earlier post. Aren't you using 2708's?

Hi, Using 2716's

 

[jetusenet]

isn't your s3 one line too low?

On this thread there are 2 different strapping for the 2716

Post #24 is the first

Post #11 is the second

 

[jetusenet]

S2 is different .....

Mine is strapped as the first pic. post #24

 

[wugly]

the bottom connection is low. you are connected under the s3. the others are connected above s3