A604n and C4 in different revisions of A604n

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Don't Panic. Please wash hands.
  • So I was just wondering. I know C4 will conflict with A600 motherboards that has non VBB Gayle chips.


    Is C4 the same in both the latest version of A604 and the next newest version which has that square chip on the left of the ECS socket? So C4 has the same function in both of these A604n revisions, and will require removal for A600 motherboards with non VBB Gayle? I noticed C4 is place on the right side of the expansion slot on the older revision, while in the newer revision it's placed to the left of the ECS socket.

  • Removal of C4 is only required for the 2016 version (with the square chip) of the board. The 2013 version, which we returned to for this current batch, is shipped with a small modification on the bottom of the board, so no action required here.

  • Removal of C4 is only required for the 2016 version (with the square chip) of the board. The 2013 version, which we returned to for this current batch, is shipped with a small modification on the bottom of the board, so no action required here.

    I have an A604n 2013 version with the black PCB bought in 2015-04-02. I also have an A604n 2016 version (with the square chip bought in 2017-11-19.


    Unless the 2016 version was sold in 2015. I'm looking through my purchase history here. So basically both of these A604n would require removal of C4 if used with a non VBB Gayle? What year did you start to ship your new batch of the 2013 version with the small modification on the bottom?


    Or you say that all 2013 versions of A604n will be fine with C4 in place when used on a non VBB Gayle?

  • So basically both of these A604n would require removal of C4 if used with a non VBB Gayle?

    No, only the 2016 version requires removal of C4. The 2013 version requires cutting a trace at the bottom, but only if you want to use Indivision ECS V2. For the 2013 version, it does not matter when it was sold; C4 should always remain in place, as it has a different function.


    What year did you start to ship your new batch of the 2013 version with the small modification on the bottom?

    That must have been early 2019, or late 2018. I therefore assume that your 2013 card does not have the modification. The layout of the 2013 version routed the C14M signal to the clock input pin of the 48-pin socket, which was meant to support Indivision ECS. When I finally designed the new version of Indivision ECS, it turned out that this signal is different on different versions of the A600. In order to make all installations behave the same, I decided to cut the trace and use a different source of information to auto-detect that "this" is an A600.


    This is a bottom view of the 2013 version. The highlighted trace is the "VBB" line (which happens to be a clock line for the non-VBB Agnus chips). This should be cut (at any point you feel comfortable) in order to make Indivision ECS V2 work properly.

  • I removed C4 from 2013 version a few years ago when I was troubleshooting some stuff. Must have been confused as to what version it was necessary on. Is C4 in 2013 version also 100nf like in the 2016 version? You say it has another function in the 2013 version so I better replace it then.


    Info about ECS V2 is interesting as I just tried a ECS V2 in the 2013 version of A604n. Looked like it was working fine. Mind you, it is missing C4 currently. Don't know if that has something to do with it.

  • You say it has another function in the 2013 version so I better replace it then.

    Yes, C4 on the 2013 version is a standard decoupling cap on the 5V rail, near the memory chip. You should put that back in place,



    Info about ECS V2 is interesting as I just tried a ECS V2 in the 2013 version of A604n. Looked like it was working fine. Mind you, it is missing C4 currently. Don't know if that has something to do with it.

    Indivision ECS V2 will work fine in the unmodified 2013 version if the host Amiga has a non-VBB Agnus. If it's a VBB Agnus, then the negative bias voltage (VBB) will be clamped by the input stage of the flicker fixer, causing parts of Agnus to malfunction. If you have a non-VBB Agnus, you're safe.

  • Yes, C4 on the 2013 version is a standard decoupling cap on the 5V rail, near the memory chip. You should put that back in place,



    Indivision ECS V2 will work fine in the unmodified 2013 version if the host Amiga has a non-VBB Agnus. If it's a VBB Agnus, then the negative bias voltage (VBB) will be clamped by the input stage of the flicker fixer, causing parts of Agnus to malfunction. If you have a non-VBB Agnus, you're safe.

    And C4 should be 100nf in 2013 version? It's long gone so I need to replace it.


    I see. Yes, this rev 1.1 A600 motherboard has a non VBB Agnus. So that's why it worked then.


    Edit: I could just transplant C4 from 2016 version. I'm guessing C4 should be around 100nf in 2013 version aswell, since it's for decoupling


    Edit 2: I have transplanted the 100nf C4 from 2016 version of A604n over to C4 on 2013 version A604n. This surface mount cap is incredible small. But all went well.

  • Yes, 100nF/X7R, 50V.

    Thanks for confirming. I did transplant the 100nf C4 from A604n 2016 version over to C4 on this A604n 2013 version. So now I could also use the 2016 version in my non VBB Gayle rev 1.1 A600 board.


    Edit: I just realised this was probably posted in the wrong section. This thread could probably be moved to 'Amiga memory expansion' section