Hi Jeff! On Fri, Jul 10, 2020 at 8:19 PM Jeffrey Birt <birt_j_at_soigeneris.com> wrote: > > I have been working on a MOS 8701 clock chip replacement that is just a bit bigger than the original so it will fit into a C128 with the RF shield cover in place. > > The design is based on Frank IZ8DWF's design from one of his videos. The PCB size is about 0.5"x0.9" with the holes on 0.4" centers. This was needed to make room for the SSOP28 clock chip. > > The 0.4" spacing required making a fixture to custom bend some leads into a 'Z' shape. And another fixture is used to align the leads for soldering. To make it even more fun the resistors and caps are 0603 size which is about as small as I care to do without a proper microscope. I built the first board this morning and it works!! It takes a fair amount of time to build one of them, and you need the special fixtures for the leads, but it was an interesting challenge. I like your method of bending the pins. At some point I had tried using pin strips with SMD pads on the other side, to maintain the small size of my original PCB, but I didn't need more replacement as of today. You've done a great job! > This version of the PCB uses cut pads to configure NTSC or PAL. I have a new design that should do this automagically. I should have some of those PCBs in a few weeks for testing. I bet you had to add some small logic gate to make this happen. I thought about automatic config too, but I've never found a good method that didn't need more logic chips. > > > > _at_IZ8DWF – Frank when I am able to confirm that PAL works, I will send you some completed units, gratis. so nice, thank you very much! FrankReceived on 2020-07-11 21:00:03
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