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4078Re: [midatlanticretro] Re: Apple II Troubleshooting Question

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  • Bob Grieb
    Aug 31, 2006
      Jim,

      If you go to www.1000bit.net, then to the manuals
      section, and select Apple, you can find a complete
      copy of the Apple ][ ref manual. Unfortunately, the
      scanning job is not great so the schematics are
      pretty much unusable, but it also has a description of
      how the video section works.

      I downloaded something called
      the Apple II mini manual, and on page 60 it has a
      complete schem of just the video circuit. This should
      help you to see how things are set up. A5 is the location
      on the circuit board of the char gen EPROM, a 2513 type.

      With a 'scope and this schem, you should be able to
      see what's not working.

      Bob Grieb

      --- macmothership <macmothership@...> wrote:

      > I'm going to try Herb's suggestion to see if it reads a disk, but I
      > suspect it will. It seems to
      > function. I just got a complete new ROM set I am going to try as
      > well, although swapping
      > with the II+ didn't change the symptoms.
      > I've had a suggestion that the charactor ROM may be the problem. Is
      > that the charactor
      > generator that you mention? The large chip under the keyboard
      > location?
      >
      > I did swap this with the II+ when doing the chip swap with no change
      > in symptoms. The
      > chip in the II looks weird, though. It is brown, has a clear circular
      > window in the middle,
      > and is marked with a large lower case letter i. But as I said
      > swapping it didn't change
      > anything.
      >
      > I know the Apple II isn't a REV 0 (It has the extra pin behind the
      > video port) but other than
      > that, I don't know any other details. I am using the B&W (green,
      > actually) Apple tilting
      > monitor
      >
      > Thanks!
      > Jim
      >
      >
      >
      >
      > --- In midatlanticretro@yahoogroups.com, "buseyl" <buseyl@...> wrote:
      > >
      > > Hi Jim, I just read about your Apple troubles (I get the digest).
      > It's
      > > kind of late tonight but maybe I can help. I have an Apple ][ rev 0
      > > and an Apple ][+ rev RFI D. All revisions of the Apple and Apple
      > ][+
      > > are very similar but there are differences so you should be careful
      > > about swapping parts. For instance, the character generator in IIRC
      > > rev 7 Apples on up was changed to be pin compatible with a 2716
      > EPROM
      > > to allow for custom character sets. If you swap incompatible
      > character
      > > generators something could get cooked. Do you know what revs your
      > ][
      > > and ][+ motherboards are? Do you know firmware does your Apple has
      > > (autostart or old monitor, integer or Applesoft BASIC)?
      > >
      > > Good news. You get video, can move the cursor with the keyboard,
      > and
      > > get the machine to beep with ctrl-G so your Apple mostly works. I
      > > wonder. Are you using a color monitor with your ][? Is the garbage
      > > color (lores) or mono (text)? I'd be curious to see if hires is
      > > working. The Applevision demo on the DOS 3.3 System Master disk
      > would
      > > probably give you a good idea but that may be hard to type in
      > blind.
      > >
      > > There're a lot of knowledgeable people here. I think the prognosis
      > for
      > > your Apple is good.
      > >
      > > Liam
      > >
      > > --- In midatlanticretro@yahoogroups.com, "macmothership"
      > > <macmothership@> wrote:
      > > >
      > > > I just want to say thanks to everyone who has taken the time to
      > > respond. It really means
      > > > alot to me, and when I eventually get this one working it will be
      > > quite a pleasure to display
      > > > it at upcoming MARCH events. It took me a long time to find an
      > Apple
      > > II and I had almost
      > > > given up hope, so I had to jump on this one, even though it had
      > > problems. Cosmetically it
      > > > is quite good. Thanks again for your help so far.
      > > >
      > > > Jim
      > > >
      > > > --- In midatlanticretro@yahoogroups.com, BOYD BORRILL
      > <b.r.borrill@>
      > > wrote:
      > > > >
      > > > > Hi Evan;
      > > > > I've been following this thread all day and would like to
      > make
      > > an offer. I have a book
      > > > published by SAMS, entitled "The Apple II Circuit Description" by
      > > Winston D. Gaylor.
      > > > > It is abut 2 inches thick, spiral bound and contains a
      > complete
      > > set of circuit
      > > > descriptions for every revision of the Apple II from the
      > olriginal
      > > through the Apple II +. It
      > > > includes timing diagrams, waveforms, keyboard differences and
      > > circuit/logic diagrams. It
      > > > thorolughly covers circuit analysis and how to tell the
      > differences
      > > by the numbers of the
      > > > various models.
      > > > > I have sold two copies of this book on E-bay for up to
      > $55.00. I
      > > recently found this
      > > > copy in a local thrift store and bought it. Considering the
      > content
      > > of this thread I would
      > > > like to offer the following: I will give this book to MARCH as a
      > > contribution to pay my initial
      > > > financial offering (because I have no cash anymore). I would
      > suggest
      > > that MARCH make it
      > > > available to members as needed, like a "lending Library" and
      > > otherwise keep it displayed in
      > > > the museum. It would save a lot of internet searching.
      > > > > Given a p;ositive response from you, and a mailing address, I
      > > could have it in your
      > > > hands in about a week.
      > > > > Ray
      > > > >
      > > > > Evan Koblentz <evan@> wrote:
      > > > > I'd guess that someone on classiccmp must have it.
      > > Perhaps someone like
      > > > > Hans Franke...?
      > > > >
      > > > > Or how about you, Tom Owad?
      > > > >
      > > > > Or just send an email to Sellam (sellam@) .... He'll either
      > > > > have it or know who does.
      > > > >
      > > > > -----Original Message-----
      > > > > From: Bob Grieb [mailto:bobgrieb@]
      > > > > Sent: Tuesday, August 29, 2006 1:15 PM
      > > > > To: midatlanticretro@yahoogroups.com
      > > > > Subject: Re: [midatlanticretro] Apple II Troubleshooting
      > Question
      > > > >
      > > > > If anyone has an Apple ][ manual, the schematic is included. So
      > > far I have
      > > > > not found a copy of it on the web.
      > > > >
      > > > > Bob A - Do you have an Apple II manual?
      > > > >
      > > > > Bob Grieb
      > > > >
      > > > > --- macmothership <macmothership@> wrote:
      > > > >
      > > > > > Last week I finilly aquired an original Apple II. I have had
      > a
      > > II+ for
      > > > > > some time, but just never found an origiinal II for the right
      > > price.
      > > > > > But this one has a problem that I'm hoping someone can help
      > me with.
      > > > > >
      > > > > > . The computer turns on with a normal beep.
      > > > > > . The monitor lights up, but with a set of maybe 4 pixel wide
      > > bars a
      > > > > > pixel or so two apart vertically up the screen. In the lower
      > left
      > > > > > there is a blinking "cursor", which is actually a block of
      > > pixels the
      > > > > > size of a character in the second bar, that blinks like a
      > cursor.
      > > > > > . The "cursor responds to keyboard input by moving to the
      > right
      > > just
      > > > > > like it should, but no text.
      > > > > > The reset button functions normally, with a beep and a
      > "return"
      > > of the
      > > > > > cursor on screen.
      > > > > > . "Control + G" rings the bell
      > > > > > . Typing "Load + Return" cycles through about 10 lines and
      > goes
      > > back
      > > > > > to the blinking "cursor"
      > > > > >
      > > > > > Over the weekend, I switched out every chip that is socketed
      > > from the
      > > > > > Apple II+ to the apple II one section or row at a time. I did
      > RAM,
      > > > > > ROMS, processor, everything. (that was a tedious job!) Each
      > and
      > > every
      > > > > > time there was no change in the symptoms. Also, I tried the
      > II+
      > > power
      > > > > > supply and keyboard. I checked the bottom of the board for
      > anything
      > > > > > strange, but didn't see anything that looks out of wack.
      > > > > >
      > > > > > It almost seems like a fault in the location that takes the
      > > processor
      > > > > > output and keyboard input and converts it or decodes it to
      > ASCII
      > > > > > characters for display on the video. If there is such a
      > place, I'm
      > > > > > just guessing, I'm not good at the component level.
      > > > > >
      >
      === message truncated ===


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