Re: Apple II plus hardware problem

["Allen Bong" <sfbong@tm.net.my>]

I didn't see the reply from Rubywand as I went into the NG, my posted
message as well as the replied message were already gone.  So Ruby,  would
you please send me your reply to me by email?

As for Andy, I do have a spare keyboard and after I changed it, the fault
was still there.  So I guess it is not the keyboard problem.  What is the
Chip B10 (74LS74) for?  It was connected to the keyboard strobe.  Should I
try this chip first?

Allen

"Andy" <NOSPAM@PRODIGY.NET> wrote in message
3a0038f4.5127248@News.prodigy.net">news:3a0038f4.5127248@News.prodigy.net...
>
> Hello Allen, it sounds like you may have more than one problem with
> your Apple II+.  In addition to what Rubywand suggests, you might try
> to check the keyboard encoder chip on the small pc card under the
> keyboard.  If you can get a schematic of the keyboard, you can check
> the chip with an ohm meter (diode checking mode-Apple turned off) and
> compare the resistance from ground to each of the matrix keyboard
> pins.  They should all be the same resistance value.  If one is
> different, the keyboard chip is probally bad.  Your best bet is to
> purchase a non-working Apple II+ on Ebay and scavage for parts as I
> couldn't find the keyboard chip anywhere.
>
> Good luck,
>
> >>> Andy
> + + + + + + + + + +
> On Sat, 28 Oct 2000 09:39:30 +0800, "Allen Bong" <sfbong@tm.net.my>
> wrote:
>
> >Hi All,
> >
> >My Apple2+ recently developed an intermittent problem.  When I switched
it
> >on, It went straight to low res graphic mode and the whole screen was
> >scrolling up accompanying with the constant beep sound.
> >
> >I checked with a logic probe and found F14 74ls259 pin 4 to pin 7 were
all
> >L, so I suspected that F14 chip was bad.  I changed the chip and the
fault
> >disappeared for a while and as soon as I plugged in the keyboard the same
> >fault came back again.  I'd removed all the cards plugged in the slots
when
> >I did all the test.
> >
> >Is there anything other chips that would caused this problem ?  I'd also
> >soldered the 6 eproms directly onto the PCB as the sockets were giving
other
> >problems last time.  Please help me if you'd any clue for me.
> >
> >TIA.
> >
> >Allen
> >
> >
>