Started by Shining, 00:45, 13 January 15
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Quote from: Audronic on 01:10, 07 January 19@llopis In general terms I would be looking at the Buffers IC202, IC203, IC204 First as these talk to the outside worldand are prone to Glitches.Just a thoughtGood luckRay
Quote from: Bryce on 10:33, 07 January 19If a different drive works on that CPC, then all the buffers are fine. I'd check what speed the disk is turning at. It maybe be on the border of being too fast or too slow and the tolerances of the other CPC (where it works) are a bit wider.
Quote from: Audronic on 11:41, 07 January 19I was referring to this Schematic
Quote from: Bryce on 12:14, 07 January 19I haven't seen that schematic version either, I don't think? Is it from the ammendment?You can check any of the outputs such as MOTORON or STEP and check that these are going low when they should.
Quote from: Bryce on 13:21, 08 January 19The only signal not shared by the internal and external drives is drive select (NDSEL and NDSEL1), controlled by IC202 (according to Audronics schematic notation). Check that this signal (Pin 10 of the 26pin connector) is definitely going low during disk access.
Quote38. LCT/DlR (Low Current/Direction)In the read/write mode, the LCT output indicates that the R/W head is positioned at cylinder 42 or greater. In the seek mode, the DIR output determines the direction the head will move in when it receives a step pulse. If DIR is 0, seeks are performed in the outward direction; DIR is 1, seeks are performed in the inward direction.
Quote from: llopis on 17:02, 08 January 19NDSEL is permanently high for me.
QuoteUS0 US1(UnitSelect0,1)The US0 and US1 outputs select up to 4 floppy disk drive units using an external decoder.
Quote from: tjohnson on 00:26, 09 January 19Is this an internal 3" drive you are having issues with? Did you say a floppy drive emulator (gotek?) works when connected to the edge connector of the computer?
Quote from: llopis on 23:50, 08 January 19On the non-working CPC, US1 never changes from the high with pulses to 0 (this is measured directly at the FDD).Any thoughts on what else I can test?
Quote from: Bryce on 10:03, 09 January 19If US1 is never going low, then that's your problem. Either the inverter isn't working / stuck high, or the 765 isn't. You need to trace where that issue is originating.
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