Phil. This is your problem, change the resistors to 150ohm, I bet you it will work, I've had this about 5 times except once, on taito L-shape SI pcbs. Andy Welburn www.andys-arcade.com
-----Original Message----- From: techtoolslist-bounces@flippers.com [mailto:techtoolslist- bounces@flippers.com] On Behalf Of Phil Morris Sent: 15 April 2005 22:35 To: Technical Tools Mail List Subject: Re: [Techtoolslist] Space Invaders
Did you check the power levels with the Fluke pod in? Seems like I heard that it draws more power than the CPU. Also, maybe you have a weak component in the CPU circuit, since adding the pod changes trace lengths, power loading, etc. does it not?
Well, some success - seems that lowering the +5VDC line to +4.5VDC gets one boardset to run via the Fluke - the other one still won't play ball though.
I'm wondering if it's something to do with the clock ..... the two resistors that interface with the 7404 at 7B and the crystal are, according to the schematics, supposed to be 330 ohms. However, on the boardset that WILL work via the Fluke they are both 150 ohms, yet on the boardset that won't work via the Fluke they are 330 ohms and 1K
I don't feel like experimenting with swapping them out right now, but maybe this is the cause.
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