[Search for users] [Overall Top Noters] [List of all Conferences] [Download this site]

Conference hydra::amiga_v1

Title:AMIGA NOTES
Notice:Join us in the *NEW* conference - HYDRA::AMIGA_V2
Moderator:HYDRA::MOORE
Created:Sat Apr 26 1986
Last Modified:Wed Feb 05 1992
Last Successful Update:Fri Jun 06 1997
Number of topics:5378
Total number of notes:38326

3252.0. "Escort HD and Minimegs Memory" by YUPPIE::WILSON (Tony, the HOSS TRUMPET) Thu Dec 21 1989 21:51

    I've had an Excort (Expansion Technologies) 65 MB Harddisk on my A500
    for about a year and just received an M.A.S.T. 1 meg memory upgrade and
    guess what!  They don't work and play well together.  Specifically, the
    power led doesn't even turn on on the memory when it attaches to the
    pass-through bus connection on the disk controller.  When I attach the
    memory directly to the CPU, it works fine.
    
    With the disk controller and the memory in place, everything works
    except the memory.  I thought at first the power might be dragged down,
    but symptomatically the whole system should fail if this were true.
    
    Any thoughts?
T.RTitleUserPersonal
Name		DateLines
3252.1broken pass-throughSAUTER::SAUTERJohn SauterFri Dec 22 1989 08:543
    The obvious thought is that your disk controller's buss pass-through
    is non-functional.
        John Sauter
3252.2Check pass thru power...HPSTEK::SENNATue Dec 26 1989 09:024
    Does the buss pass through pass power? I wouldn't if
    I were them! You never know what people might attatch
    out there!! You shouldn't try to run them both off of
    the 500 power supply anyway, if you are!
3252.3It's still under warrantyYUPPIE::WILSONTony, the HOSS TRUMPETTue Dec 26 1989 22:0610
    I took the drive back to the dealer for checkup.  As an 18 year student
    of things like UNIBUS, I guess I expected more when they call it a
    "Buss".  Yes, I suspected that power was not being passed through, but
    after looking at the runs (clads), power seems to be connected from one
    side to the other (I don't have a Ohmmeter).  It is most probably one
    of the plate-through holes doesn't quite make the connection.  I've
    seen this happen frequently.
    
    As for having enough power, I'm taking a wait-and-see approach.  If the
    power sags, I'll get a bigger brick.
3252.4POTS::VISSERThu Jan 11 1990 09:5737
    Wait a minute.  You shouldn't be trying to power anything but the
    backplane's buffers, data direction, collision detection, and
    bus acquisition logic from the '500.  I don't have the '500 spec. with
    me, but the '1000 supplies a maximum of 1 Amp at +5 Volts to the
    expansion port; '2000 slots are spec'd to deliver 4 A, and indeed many
    cards will use it.  The A2090 HD cotroller is spec'd at 3 A max.    
    
    "after looking at the runs (clads), power seems to be connected from
    one..."
    
    Maybe they have a multi-layer board with a power and ground plane, and
    that's why you won't see seperate etch for the power.  Check pins 5 and
    6 on both sides; these are the +5 V connections.  An Ohmmeter is a good
    investment, try Radio Shack's absolute cheapest at < $10.00.
    
    
    "It is most probably one of the plate-through holes doesn't quite make
    the connection.  I've seen this happen frequently."
    
    I have never, ever seen this happen with good artwork.  If it does
    either the artwork or the board manufacturer stink.
    
    "If the power sags, I'll get a bigger brick."
    
    This won't work.  The amount of power delivered to the expansion port
    is limited by the amount available from the supply AND the current
    carrying capability of the path to the load.  You might smoke the
    connector or the etch if you overload the port;  hopefully there is a
    fuse inside the Amiga between the system power and the expansion port. 
    
    You will probably need to externally power your accesories.  If you need
    some help doing this, let me know.
    
    John
    223-1852
3252.5Fuse???HPSTEK::SENNAThu Jan 11 1990 11:304
    re: .4
    
    The only fuse in the 500 is the weekest component/etch in the path 8^)
3252.6Buy my tools at Radio ShackYUPPIE::WILSONTony, the HOSS TRUMPETThu Jan 11 1990 11:3313
    Thanks for the input.  I have seen COHU camera controller systems fail
    over and over and each time it happened, I traced it to a
    plate-through.  I finally resolved this by soldering bare wires through
    every hole in the board.  I never had another problem with the board. 
    
    As far as being able to supply current from one side of the board to
    the other, the MINIMEGS works when plugged directly into the computer. 
    Surely the clad on the controller board is big enough to ship the power
    across to the other side.
    
    The disk drive has a separate (and substantial) power supply.  I don't
    know whether it supplies to the controller or not.  If it does, it
    should provide adequate power.
3252.7Get a bigger hammer...YUPPIE::WILSONTony, the HOSS TRUMPETSun Jan 14 1990 00:2810
    I purchased a DVM to test the Escort board.  Although my new DVM
    doesn't work, the Escort now does!  The pressure on the board while
    attempting to measure voltage must have caused it to start working. 
    Both Escort and memory are doing fine.  (HandyWB does not start up
    correctly with it, though.  I took it out of the startup sequence and
    started it from the icon later and it seems to work.  I will research
    this one.)
    
    Tony