Strange RiscPC floppy fault

Arc/RPCs, peripherals, RISCOS operating system & ARM kit eg GP2x, BeagleBoard
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Strange RiscPC floppy fault

Postby Boydie » Mon Jul 17, 2017 2:12 pm


I've been gradually restoring my first RiscPC (Issue 1 board) to fully working status following nasty battery damage. It's almost fully functional following repair of a bad track between IC16 and VIDC (wouldn't start) and replacing C122 (very shaky video). I thought all was fine apart from the built-in speaker not working (audio out socket is fine), down to what looks like battery damage to C162 (I think that's the correct number - it sits in the audio path to the built-in speaker, right next to the battery).

I've since discovered another, bizarre fault. With a disc in the drive, clicking on the floppy icon causes brief (about half a second) screen corruption, and results in Disc Error 02. Occasionally, it complains disc not formatted, instead.

So far, I've tried different floppies (all work fine in other machines), a drive from a different RPC, an alternative power cable from the PSU, using a different PSU to power the floppy. The fault persisted across all of these. I've checked for continuity between the floppy connector and IC5, 0V, and +5V, and all checks out as it should, with appropriate resistances if there are resistors in the path. It all checks out fine.

Any suggestions for where to look next?