Re: [N8VEM: 14618] SBC V2 build not working

[vk5dg <vk...@internode.on.net>]

/BUSRQ is now LO since you pulled out U17.  Better put U10 and U14 back in or you won't get any I/O working.

One test is to remove U15 and measure with an ohmmeter if the FLASH /CS line is being pulled high and there is continuity between U15 pin 8 and U2 pin 22.  If ok swap U15 and U14 to see if U15 is the culprit.  Failing that it's a case of working your way back through the RAM/ROM memory decode section of the schematic.

Regards

David

On Friday, 14 September 2012 16:47:16 UTC+9:30, opticpow  wrote:

Hi All,

Today I removed all the non-critical chips (i believe, photo below) and done some testing. Something interesting that I found is that the flash CS is still at that strange 2.5-5v level (see the scope grab below), but tracing it on the schematic to U15 pin 8, checks out as a solid high @ 5v. How can this be?

The other thing I noticed is that while /RESET, /INT, /NMI are high, /BUSRQ is low.

Thanks, Wayne.