Re: Apple II Minus Question

["Bryan Parkoff" <bryan.nospam.parkoff@nospam.com>]

Rubywand,

    Didn't you understand?  I trashed all old 74xxx chips and static RAM
chips.  Cleaning chip's pin is not worth.  I bought new 74xxx chips and
static RAM chips from electronic store a month ago.  They are IDENTICAL to
the OLDEST 74xxx chips and static RAM chips.
    How do I clean each socket's hole (Not Pin)?

-- 
Bryan Parkoff
"Rubywand" <rubywand@swbell.net> wrote in message
403E7B43.16FF6EBF@swbell.net">news:403E7B43.16FF6EBF@swbell.net...
> Bryan Parkoff writes ...
> >
> >     I would like to know Apple II Minus history that it is the earliest
> > model that it starts with Old Monitor Routines rather than AutoStart
> > Routines.  Do white horizontal block like GR (low resolution) appears in
the
> > screen?  Or...Do white horizontal block like TEXT ("@@@@" and "??????")
> > appears in the screen?
> >     If it is GR, must you always press RESET before it returns to "*"
> > prompt?
> >     First, you turn on Apple II Minus.
> >     Second, odd lines (1, 3, 5, 7, 9, etc) appears "@@@@@@@@" and even
lines
> > (2, 4, 6, 8, 10, etc) appears "????????".  They are all inverse.
> >     Third, "*" prompt appears in 24th line.
> >
> >     Sometimes, "???>@.?1??<??" show.  Do you suspect that it may be bad
RAM?
> > Or it may be static leakage?
> >
> >     Are all "00 00 00 00 00 00 00 00" store in odd pages between $0000
and
> > $BFFF and "FF FF FF FF FF FF FF FF" store in even pages between $0000
and
> > $BFFF?  If each page do show like "01 01 01 01", "7F 7F 7F 7F", "E1 E1
E1
> > E1", "FE FE FE FE", or etc.  I claim that all static RAM chips are bad.
It
> > is why I have Apple II Minus and Apple II Plus motherboards that are
> > defective in my hand except extra Apple II Plus is working OK.
> >
> >     I bought all 7xxxx chips and RAM chips from electronic store.  I
removed
> > all old chips out of all sockets.  I threw them in the trash.  I put new
> > 7xxxx chips and RAM chips in all sockets.  I did test, but the result is
> > still the SAME.  Such as GR and HGR are not working (never turn on, but
stay
> > in TEXT only).
> >     It may be motherboard that is bad.  Probably some resistors,
capicators,
> > and other electronic parts are bad however all chips are working fine on
> > another Apple II+ motherboard.  I do have Apple II+ repair manual.  It
does
> > provide me a lot of information, but it does not specify where defective
> > occurs.  It suggests to use electronic diagnostic tools to measure
voltage,
> > resistors, currents, etc on the motherboard.
> >     Please suggest which electronic diagnostic tools that is very worth
for
> > me to buy before I can be able to isoslate defective parts.  If I have
found
> > defective, I would be ABLE to repair.  Please advise.
> >
>  ....
>
>      The best diagnostic tool is usually the computer itself-- you try
> different things and notice what it does.
>
>      Maybe some RAM interface IC is loose or defective. Try pulling and
> cleaning the pins of the 74LS174's at B5 and B8 (near the front of the
> motherboard). Do the same for the 74LS257's at B6 and B7.
>
>      If that doesn't fix things, try pulling and resocketting every IC.
It's
> pretty common for old computers to develop problems due to loose IC's or
IC's
> which have developed corrosion on pins. (Out II+ did that about a month
ago.
> Pulled and cleaned the IC's and the II+ has been working fine since.)
>
>
>
> Rubywand