lyra 2 bigbox wiring

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Don't Panic. Please wash hands.
  • Hello,


    i want to rewire my lyra 2 bigbox to western plug for using it with an amiga 1000. I hope that's possible.

    What is the color code. When i open up the lyra 2 bigbox, i can see a brown, green, yellow and orange cable.


    Thanks

  • i want to rewire my lyra 2 bigbox to western plug for using it with an amiga 1000. I hope that's possible.

    That'll be possible - I have never tried it myself, but I know for sure that the protocol is the same.


    What is the color code. When i open up the lyra 2 bigbox, i can see a brown, green, yellow and orange cable.

    There are no fixed colours, as cable vendors have changed over the years. Lyra2 is based on the Lyra1 hardware that I designed in March 2001, so over 19 years ago. The version step from Lyra1 to Lyra2 was made in October 2008 when we switched to a new (but pin-compatible) chip. You may have either a gree, or a blue circuit board (where blue is more probable).


    I do not have the old CAD system any more that I used to design that board. However, I found this picture:

    Red and Orange directly go to a decoupling cap, so that's the two supply lines. You'll have to measure which one is GND and which one is Vcc. It is wrong to assume that "red is plus" in this case - you only have a 50% chance for this to be true. Your multimeter will give you the answer. If you don't have a multimeter, you should NOT attempt the mod, as you'll burn the chip otherwise.


    Black and yellow are clock and data. Again, I have no way of telling which one is which, but it's safe to just connect them and see if it works on the A1000. If it doesn't, just swap the signals and it'll work. Again, 50% chance for "first time right", but in this case, measuring won't help (where it's mandatory on the supply lines).


    Sorry for not being of more help - it's just too long ago.

  • Thank you Jens,


    unfortunately, it looks like i have fried my chip already before writing this post...

    Now my chip either way i connect the red and orange cable, just gets quite hot.


    I got at least the startup blinking from my keyboard, but that also works without the pic chip.

    I was wondering, if it's easy to get one of those chips 12c672/p already pre-programmed from you?


    Or maybe i can get a programmer and one of those chips i could flash the eeprom myself, if you would give me the software?

  • I was wondering, if it's easy to get one of those chips 12c672/p already pre-programmed from you?

    While I still have the programming equipment, I don't have the chips any more, and I refuse to buy any Microchip stuff any more. Their pricing policy ist just destructive for small businesses like mine, so I won't be supporting them with a single cent any more.


    Or maybe i can get a programmer and one of those chips i could flash the eeprom myself, if you would give me the software?

    That would require a total-buyout of the Lyra product line, which is not for sale at the moment. It'll be most cost-effective for you if you just go for a new Lyra3 "big box".

  • Ok, thanks, i can understand that. Just ordered one.

    How can i make sure, then that i don't fry again the chips. Do you have the schematics to post here?

    And any suggestions how to modify it.


    Thanks :)

  • Sure, the new version is made in my current CAD system, so I have that at hand:

    Please enlarge the picture to see the signal names. Note that this version is a multilayer board, so you'll need a good soldering iron for VCC and GND. I guess the best idea to not fry it is to make sure you're counting from the correct side. I haven't done an A1000 mod myself, but would take special care to find the GND and VCC lines by doing continuity and load measurements, as the VCC line may be confused with one of the data/clock lines if you only measure with a volt meter. If you load your line-under-test with a 470R resistor, the voltage should remain near 5V and the resistor should get hot. For Dat and CLK, the voltage will drop considerably.

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