At startup, the floppy drive makes noises then the desktop is displayed without drives A nor B (video 1: https://youtu.be/DYs9ybEFtOI).
If I add an ultrasatan, the floppy drive still makes noise, the ultrasatan works fine (all programs too), but no access to the floppy drive (Message is : "the selected drive does not exist") (Video 2 : https://youtu.be/-Gx67mWr7qY)
Using the diagnostic cartridge
- Memory 1 MB -> OK
- ROM -> OK
- Keyboard -> OK
- Audio -> OK
- floppy drive test -> noise then message "F0--Drive not selected" KO
Here are all the tests and actions I did (but did not change anything)
What has been tested (on another machine) so I'm sure they work:
- WD1772 -> OK
- DMA C398739-001A -> OK
- PSG YM4921F -> OK
- Floppy drive -> OK
- Floppy disk -> OK
- CPU -> OK
- C301712-001 -> OK
- U305 (SN74LS06) -> OK
What has been done but still do not change anything:
- 4700uF Exxos capacitor -> no change
- Mandatory #1 - PSU SR98 Recapped -> no change
- Mandatory #2 - Not necessary, 4 strips of 256KB 8 chips without parity -> no change
- Mandatory #3 - DMA Pull Up -> no change
- Mandatory #4 - 1772 Pull Up -> no change
- Mandatory #5 - CPU changed to HC Type -> no change
What I also did but (again) did not change anything:
- Changed the cable to the floppy drive -> no change (Power to the FD is good +5v +12v)
- Changed U304 (74LS74) -> no change
- Changed U306 (74LS74) -> no change
- Changed U307 (74LS244) -> no change
- Changed U308 (74LS245) -> no change
- Changed C204, C205 -> no change
So I don't know what to do anymore. I also tried looking for a cut trace on the motherboard but couldn't find any.
Would you have an idea (or two) to explore ?
Thanks.
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