Well, flawless isn't so true after all. It worked flawlessly on the test bed, but wouldn't work in the game...so I tried various combinations of Supervisor IC's resetting the 6821 independently of the 6809 - this also worked on the bench but not in the game. Now I'm really ticked. The stupid sound board works fine with Police Force ROMs (strapping fixed), but not with the 512 ones for Riverboat Gambler. Gave up and installed a sound board from a Midway basketball game that used the same board - it works just fine with the same ROMs as were in the defective sound board. I am considering tracking this down further, but I have several spare sound boards and lots of other projects that are more important - but I do hate surrendering to a stupid PCB! Maybe some day I'll take a good board and the flaky board and do a 9010 LEARN function and see if there are any differences when the board is not booting... John :-#(# At 12:11 PM -0800 2/23/05, John Robertson wrote:
Once I added the RESET jumper to the 68B21 the pod worked flawlessly. It's a 68B09E CPU by the way...
however the board is not working in the game - but if I force a reset it does. Yet the game MPU IS sending the RESET signal, but I think the original powerup should have a proper RESET on the audio board. SO I shall experiment with a NOR or NAND gated Supervisor IC to see if that makes it work better. However, first I'll secure the boards to get the ground path solid...
I must be missing something!
John :-#)#
At 11:54 AM -0800 2/23/05, Tony Gonzalez wrote:
Maybe the Z80 pod may also have some kind of similar issue as well?
Tony
--- John Robertson <jrr@flippers.com> wrote:
It's starting to look like a design flaw. The 68B21's RESET line is simply tied to Vcc through a pull-up resistor. I've now jumpered that to the board RESET line and I get a clean start up almost every time (I have substituted a good 68B21 to no avail previously).
Sooo, if this works in the game, another Tech Tip will appear on RGP I guess.
John :-#)#
At 11:51 AM -0600 2/23/05, Robert C. Bullock wrote:
John:
----- However when I replaced the suspect 175, no sounds, and when I put the original 175 back in the (now socketed) PCB, I don't get the sounds even with the Bugtrap the same way. -----
Hmm, the only similar thing I've seen is a bad -5V reg (7905) on Atari Roadblasters in the sound section. Putting my logic comparator on one of the chips fixed a problem with the scrolling playfield, but killed the sound. Take it off, it scrolls again, sound works.
Replacing the voltage regulator fixed it. The voltage on the pulse to sync that section of the board was low.
You'll have to Google this or give me a deal on that pinout cart :) and I'll dig the particulars back out. This sounds somewhat similar.
_______________________________________________ Techtoolslist mailing list Techtoolslist@flippers.com
http://seven.pairlist.net/mailman/listinfo/techtoolslist
-- John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9 Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, VideoGames) www.flippers.com "Old pinballers never die, they just flip out" _______________________________________________ Techtoolslist mailing list Techtoolslist@flippers.com
http://seven.pairlist.net/mailman/listinfo/techtoolslist
__________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com _______________________________________________ Techtoolslist mailing list Techtoolslist@flippers.com http://seven.pairlist.net/mailman/listinfo/techtoolslist
-- John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9 Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, VideoGames) www.flippers.com "Old pinballers never die, they just flip out" _______________________________________________ Techtoolslist mailing list Techtoolslist@flippers.com http://seven.pairlist.net/mailman/listinfo/techtoolslist
-- John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9 Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, VideoGames) www.flippers.com "Old pinballers never die, they just flip out" _______________________________________________ Techtoolslist mailing list Techtoolslist@flippers.com http://seven.pairlist.net/mailman/listinfo/techtoolslist