Folks, I've determined that the piece of my S/23 that's causing the power supply to blow its 12V fuse is the machine update card. The manual says this provides additional R/W storage for microprogram updates. That sounds like something that wouldn't be necessary for normal operation.
Questions: 1. Can anyone confirm that I'm not losing anything by just pulling this? 2. Anyone have a cross ref for the IBM house numbers on these chips? 3. Anyone have a spare card they'd part with? 4. As long as I'm dreaming, anyone have a set of BRADS floppies or images? Machine update card photo: https://sysovl.info/pages/galleries/ibm/s23guts/s23guts13.jpg Interestingly, the underlying PCB for this seems exactly the same as the one for the word processing feature card. Many thanks, De
