> -----Original Message----- > From: Jon Elson [mailto:[email protected]] > Sent: 01 January 2018 18:07 > To: [email protected]; Rob Jarratt <[email protected]>; General > Discussion: On-Topic and Off-Topic Posts <[email protected]> > Subject: Re: ZX Spectrum Z80 Keeps Resetting > > On 01/01/2018 11:22 AM, Rob Jarratt via cctalk wrote: > > I just replaced the last of the electrolytics, but the spikes on the > > Z80 5V rail have not gone away. They only exist on the 5V rail in > > close proximity to the Z80, other chips with a 5V supply don't have > > the spikes on the 5V rail. > > > It could be caused by bus contention, which may also be the cause of the > resetting. Possibly some of the decode logic has failed, and is allowing two > devices to drive the data bus at the same time. I've seen this before, and it > does cause spikes on the 5V rails. >
That is interesting, I hadn't considered that. Given that it gets a fair way into the boot sequence it would have to be an intermittent failure. Regards Rob
