kodak80 blog

[kodak80]

Okay, my MIDI Opto fix adapter boards arrived today that swap pins 4 and 5 on the opto-isolator IC on the mATX ST board. If anything, the fix adapter makes things worse as MidiMaze cannot communicate at all over the MIDI cables with the fix in place. Clearly there is something else wrong with the MIDI schematic on the micro ATX ST board.

[kodak80]

Yes, 8 bit ISA slot is what is in the EtherNEC adapter.

I have built up 3 x 8 bit network cards from this one: https://github.com/skiselev/isa8_eth

I need to find a way to program the 93C46 - 1 Kbit EEPROM as the network cards do not seem to work without the chip being programmed. A program is provided to do this but I don't have a working PC with an ISA slot at the moment.

Purchased an ATX motherboard with ISA slots to allow me to program the 93C46 - 1 Kbit EEPROM. Connected a gotek drive, booted to DOS 3.3 and then used the PG8019.EXE and CFG to get the job done. The CFG updates and increments the MAC address after each successful use.

rig for programming 93C46 IC.jpg (161.37 KiB) Viewed 2326 times

All 5 programmed network cards ready for testing. LED link light now lights up when I plug in a network cable:

kodak80 isa8_eth boards.jpg (158.29 KiB) Viewed 2326 times

[JezC]

Yes, 8 bit ISA slot is what is in the EtherNEC adapter.

I have built up 3 x 8 bit network cards from this one: https://github.com/skiselev/isa8_eth

I need to find a way to program the 93C46 - 1 Kbit EEPROM as the network cards do not seem to work without the chip being programmed. A program is provided to do this but I don't have a working PC with an ISA slot at the moment.

Purchased an ATX motherboard with ISA slots to allow me to program the 93C46 - 1 Kbit EEPROM. Connected a gotek drive, booted to DOS 3.3 and then used the PG8019.EXE and CFG to get the job done. The CFG updates and increments the MAC address after each successful use.


rig for programming 93C46 IC.jpg


All 5 programmed network cards ready for testing. LED link light now lights up when I plug in a network cable:


kodak80 isa8_eth boards.jpg

Lovely!

Now all we need to hear is how @PhilC is getting on with the version of the ATX board for the Mega ST form factor!

[PhilC]

@DoG i wish I could say I’d nearly finished it but it’s going to be a long job for me.

[LarryL]

Okay, my MIDI Opto fix adapter boards arrived today that swap pins 4 and 5 on the opto-isolator IC on the mATX ST board. If anything, the fix adapter makes things worse as MidiMaze cannot communicate at all over the MIDI cables with the fix in place. Clearly there is something else wrong with the MIDI schematic on the micro ATX ST board.

Hi,

The original PinOut is absolutely Ok for the 4N33, but the chip itself seems to be not suitable - too slow.
I have been successful with a CNY17F (available via e.g. eBay) using the original pinout
At least using a Diag Card and a MIDI Loopback cable this gives me a „pass“ (I do not own any MIDI equipment to check)

But: the CNY17F should not be optimal (not sure why, but an expert told me)

A more original replacement of the PC900 is a H11L1 (or H11L3) - which is still produced and available easily
Then you indeed need the adapter PCB to flip pins 4 and 5 - but you also might need 5V on pin 6
I will try this next weekend

Regards
Michael

[kodak80]

Hi,

The original PinOut is absolutely Ok for the 4N33, but the chip itself seems to be not suitable - too slow.
I have been successful with a CNY17F (available via e.g. eBay) using the original pinout
At least using a Diag Card and a MIDI Loopback cable this gives me a „pass“ (I do not own any MIDI equipment to check)

But: the CNY17F should not be optimal (not sure why, but an expert told me)

A more original replacement of the PC900 is a H11L1 (or H11L3) - which is still produced and available easily
Then you indeed need the adapter PCB to flip pins 4 and 5 - but you also might need 5V on pin 6
I will try this next weekend

Regards
Michael

I will give the CNY17F chip a try. Will also give the PC900 / H11L1 / H11L3 a try with 5v on pin 6 and pin 4/5 flipped.

[exxos]

I will give the CNY17F chip a try.

Think we used that on the H5 ? Was also listed as a compatible replacements for MIDI gear "according to the internet" IIRC.

[atari030]

Going well, mate. I have a box full of NE2000's if you run dry. Pulled them from PC's way back when. I still haven't had time to get into the workshop. It's starting to drive me nuts.

[kodak80]

Okay, I have the mATX ST MIDI in working now with original pinout. Using an alternate optocoupler CNY17F-3 chip borrowed from one of my H4 boards.

CNY17F-3 Optocoupler.jpg (289.61 KiB) Viewed 2213 times

MIDImaze 2 connects and works

[JezC]

MIDImaze 2 connects and works

That's the second most important use for the MIDI sockets IMO!

Great news though...still waiting to see how the move into a Mega ST form factor progresses (but no rush on my part...way too many other things to sort out first...second H4 build to complete, fix first H5(C), build second H5(B), fix 2x Amiga 500s etc etc etc)