Apple II plus hardware problem

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

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