On 01/10/2012 09:26 PM, mwillegal wrote:
Could be a ground or power supply issue. Check input voltage levels. With power disconected, compare resistance between power and ground for each power supply input with a good board and your board - don't expect exact match, but it should be in similar range. Check power off resistance between various ground points on the motherboard and power supply ground.
Both the primary system AND my backup GS (mis)behaved in the same manner with the LittlePower connected. The voltages look fine, but I'm thinking it may not provide a solid ground reference. That would account for the Disk 3.5 current waveform emerging from the speaker, and may also explain the freezeups with the Phonenet transformer. I'll bet that looks like a relatively low-impedance load and may push the ground-bounce over the edge.
When I'm a little fresher tomorrow, I'll put a scope on the rails and find out what's going on. This is all just speculation at the moment.
All of this merriment is peripheral to the original instability of the first GS, which happened with the Innerdrive power supply... Probably two unrelated issues.
Fun stuff! Steve