ACA1233n IDE Accel not work at all

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Don't Panic. Please wash hands.
  • Hey,
    i tried to test my new ACA1233n with enabling IDE speedup, no matter what i will set (other than Safe Default) System loses disk.
    Tried on 3 different CF cards(different brands) , 2 different CF Adaptors (1 directly attached to board no cable at all) , one physical disk (2 different cables).
    My A1200 board is brand new Re-Amiga 1.2 (based on 1D4 board).
    Any ideas?

  • Well, mine is an Original Power supply that i got NOS, and recaped it just to be sure.
    Well i can hook laboratory class regulated power supply and finetune it to match baseline parameters.
    Additionally what i can see ACA is Rock Stable , now i am running 36 Hour run of heavy antivirus scanning loop involving unpacking heavy archives disk images with heavy usage of ram, etc. No issues spotted.
    Well if power is an problem then in theory amiga should be unstable in heavy load.
    That test is passed.
    I will redo IDE tests with different power source.
    i forgot to mention that my ACA is @40MHz that can be an factor.

  • Well i can hook laboratory class regulated power supply and finetune it to match baseline parameters.

    That's of course a great opportunity. If you have access to that kind of equipment, you surely also understand that the input coil of the A1200 plays a big role, as voltage drop on both the GND and 5V lines add to the equation: You should measure voltage behind that input coil to be sure that at least 4,85V reach the accelerator.


    Well if power is an problem then in theory amiga should be unstable in heavy load.
    That test is passed.

    The accelerator pulls low on the IOR/IOW lines, which are pulled high by the NMOS drivers of the Gayle chip. This appears to be voltage-sensitive.


    Well if power is an problem then in theory amiga should be unstable in heavy load.

    The Amiga chipset is very forgiving if it comes to over/under voltage. Also, the logic on the ACA1233n runs off a local 3.3V regulator, so the input voltage being a bit off doesn't cause big trouble. It just seems that some CF cards (especially on unbuffered interfaces) don't like the not-completely-0V-level of the fast IO lines if controlled externally by the ACA1233n.

  • Jens - case clsoed
    Looks like IDE Accell is quite sensitive on EM Noise generated by board + capacitors used on board.
    It will simply not work if capacitors on board are tantalum ones, especially on +5V line.
    It works like a charm on board with electrolitic capacitors.
    Additonally at last bottom EMI sheild need to be installed.

  • Additonally at last bottom EMI sheild need to be installed.

    If you had removed that, it would have been worth mentioning, right? Yes, practically all Commodore computers largely depend on the EMI shield to be installed and screws tightened, as ground noise kills signal integrety otherwise.

  • The last reply was more than 365 days ago, this thread is most likely obsolete. It is recommended to create a new thread instead.