From - Tue Jun 18 17:39:35 1996 Path: masters0.news.internex.net!newshub.internex.net!newshub1.internex.net!news.Stanford.EDU!agate!howland.reston.ans.net!swrinde!newsfeed.internetmci.com!news.campus.mci.net!calweb!jolt.pagesat.net!pagesat.net!news.paonline.com!usenet From: Rodger Boots Newsgroups: rec.games.video.arcade.collecting Subject: Re: TECH: weak sync signals Date: Tue, 18 Jun 1996 04:30:59 -0700 Organization: cedar-rapids.net Lines: 27 Message-ID: <31C69373.64BB@cedar-rapids.net> References: <> <4q5nt4$5gc@tilde.csc.ti.com> NNTP-Posting-Host: sl1.cedar-rapids.net Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Mailer: Mozilla 2.02 (Win16; I) To: keay@tiuk.ti.com John Keay wrote: > > > In doing some Jamma conversions, I've come across three games which seem to > > fail to sync on my (raster) monitor, and one more which sometimes syncs > > horizontally (but not vertically), and sometimes fully fails to sync. > > > > I thought I'd convinced myself that it wasn't my monitor's fault, but now > > I'm beginning to think that maybe my monitor needs stronger sync signals > > for some reason. > > > > Any suggestions? > > Yes, I've had this a couple of times as well. The boards work okay on some > monitors but don't sync up well on others. The sync signals are easy to > buffer. Sync signals (even HSYNC) have a much lower frequency than the RGB > signals and are digital rather than analogue so unlike the RGBs they are easy > to buffer and invert. > > Use a couple of TTL inverters in series (or almost any other spare TTL > chip you have lying around) to buffer them. This worked for me (somewhat > unexpectedly) on two of my boards, so I added the buffering chip to my > JAMMA conversion harness for that game. Or if you need something REAL nasty, you can use a 555 timer IC. Pin 1 goes to ground, 2 and 6 connect together and become the input, 3 is the output, 4 and 8 go to 5 volts, 5 and 7 don't connect anywhere. The result is an inverter with a .2 AMP drive! If that doesn't work you really do have a problem!