From - Thu Feb 20 18:40:23 1997 Path: jupiter.dnai.com!news.c2.net!re.hotwired.com!j6.inktomi.com!nntp2.snfc21.pbi.net!news.pbi.net!su-news-hub1.bbnplanet.com!cam-news-hub1.bbnplanet.com!news.bbnplanet.com!howland.erols.net!cs.utexas.edu!geraldo.cc.utexas.edu!piglet.cc.utexas.edu!jwelser From: Newsgroups: rec.games.video.arcade.collecting Subject: TECH: Kick fix Date: Wed, 12 Feb 1997 16:07:44 -0600 Organization: The University of Texas at Austin, Austin, Texas Lines: 38 Message-ID: NNTP-Posting-Host: piglet.cc.utexas.edu Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Sender: jwelser@piglet.cc.utexas.edu Hey all, I just finally fixed a Kick (MCR I CPU, MCR II sound and video boards) boardset that I posted to the group about. Symptoms: No sound. I got a "Sound Board Interface Error" no matter what test mode theboard was in. The LED indicated no bad ROMs/RAMs. The fix: I started probing around with a scope, and found that the analog outputs of the 8910s were flatlined, AND the outputs of the LS191s were incorrect (Not time-varying at all.) Thus, I knew that the immediate problem, at least, was not in the analog section of the board. I swapped out the 8910s with good ones, and there was no change. I started pulling TTL chips, in order of their likeliness to send bad data to the 8910s (i.e. if they drove or buffered the Sound data bus.) I found a bad LS166 (I think that's the number...it's a shift register...) and replaced it. This got rid of the "Sound Board Interface Error" messages, but I still got no sound out of the board. I DID notice, though, that the yellow LED stayed lit solid with normal operation (or any operation, actually.) To make a long story short, I wound up pulling, testing, socketing, and replacing/reseating all of the TTL chips on the board. This still didn't fix the problem. I looked at the inputs of the Z80 and the inputs of the 8910s during the channel test self-test on my TRON, and compared them to those on my kick. Now, it was pretty obvious that the address bus of the CPU was getting bad data. I checked continuity of the address and data busses, and noticed that the D0 output of one of the ROMS wasn't connected to all the rest (the data bus.) So, I replaced that socket (the pin was broken underneath the socket) and powered up my board, and got to hear the sounds of Kick for the first time in like 10 years.... Sorry to blabber on, but I just hope that this might help someone out in the future.... Joe