> On 23 Aug 2017, at 00:49, Rob Doyle via cctalk <cctalk@classiccmp.org> wrote: > > It's a little switching power supply. It steps up the 9V input voltage to > something a few volts greater than 12V to feed the 12V regulator. > > If your 12V is correct, it is probably working. >
This is from 2 months ago but I was puzzling over the 12V circuit in this particular machine and also maybe suffering from a red herring since the PSU I was using is from a ZXSpectrum+2 which is an unregulated 12-14V lump so the coil was already being fed 12V. A > Rob. > > On 8/22/2017 4:30 PM, Adrian Graham via cctalk wrote: >> Hi folks, >> Failing Atari PSU aside I remembered a question I had ages ago but never >> posted about the power circuit of another 80s home micro, the Enterprise 64. >> This machine is powered by a 2A 9V unregulated PSU and internally there’s a >> pair of 7805s and a 78L12 to smooth things out. >> There’s also a small transformer coil in there too (L1 on the following >> schematic) and I’m not entirely sure what it’s for. Here’s the schematic of >> the original circuit, any enlightenment gratefully received since I have an >> Enterprise 64 with a dead coil :) >> http://www.binarydinosaurs.co.uk/ep64PowerRegulators.png >> <http://www.binarydinosaurs.co.uk/ep64PowerRegulators.png> >> Cheers! >> — >> Adrian/Witchy >> Binary Dinosaurs - Celebrating Computing History from 1972 onwards >
