Image Map Image Map
Page 2 of 2 FirstFirst 12
Results 11 to 14 of 14

Thread: Apple II Clone Keeps Repeating Keys - Help?

  1. #11

    Default

    Quote Originally Posted by David_M View Post
    Powering on with a screen full of question marks is a completely different scenario than a screen filling with question marks after pressing a key.
    You need to be really clear on the fault description for advice to be good enough to be of any help.

    Did the fault change after you reseated the chips or did it always have a screen full of question marks at power on?
    Does it power on normally without question marks with the keyboard unplugged?
    Does it power on normally without question marks with the keyboard plugged in and olny starts generating question marks after you press the "?/" key?

    Also when I suggested the reflow, the problem is more likely on the scanlines and the associated pull up resistors not the individual keys. Posting a photo of the chips on the keyboard will allow me to point you at the chips most likely to be the problem.
    Due to the inaccurate description of the fault you probably should expand your fault search and check the mainboard IC's at B5, B6, A12 and C11
    The screen was filling with question marks after pressing a key, I re-seated some chips and the problem changed into a pre-filled screen on boot.

    Using some bodge wires I managed to get it back to regular boot + screen filling with question marks upon pressing a key, so to answer your questions:

    1. The very first time I powered it on, the screen was full of question marks with some flashing squares scattered here and there. I re-seated some chips and it booted normally, which is when I encountered the problem where trying to type a question mark would progressively fill the screen with them.

    2. Sometimes on boot the question marks begin to scroll immediately and can be stopped by hitting Return. Powering it on with the keyboard unplugged doesn't change this, it seems completely random. Other times it boots just fine until you try to make a question mark. Occasionally the "<", "7", and ";" keys trigger the exact same problem as the question mark one, but with those characters instead. This isn't all the time though, the only constant problem occurs when trying to make a question mark.

    3. See above.

    After fiddling with it for a few days it's clearly above my current skill level and I'd rather have money for other projects, so it'll be going on eBay on Sunday. Thanks to everyone for your help! Hoping the next owner figures it out.

  2. #12

    Default

    Actually ignore that last part of my reply, I can't edit it because it hasn't been posted yet (pending moderation due to my account being fairly new).

    I think I'll persevere with this and try to figure it out. The clone is pretty cool and I'd like to hang onto it and get it running properly since I'm passing on my Apple IIc soon, and I just got a good deal on a Disk II (still need an interface card though, any Australians got one to spare?) - I'll check those ICs and report back. I'll also take some proper photos of the board.

    I was looking at some photos of real Apple II boards online and the positioning of some of my chips appear to be different, but it should be easy enough to figure out which are which.

  3. #13

    Default

    If this clone is designed like an Apple II / II+ with 3 rows of memory, try pulling out all the memory and put a different set of chips in the row closest to the front. Memory is usually outlined by a white square.
    Failed memory in the first row will give the symptoms you describe. It should beep and show a title with good memory only in the 1st row (16K of memory). Share a photo of the motherboard if needed.

    Larry G

  4. #14

    Default

    I left this alone for a long while and moved onto other projects, but since my last post I've worked on two IIe Platinums and a IIe Enhanced and eventually gathered enough confidence working with Apple II's to have another try at this. And I figured it out!

    It ended up being the keyboard. I got another II Plus clone for free from a friend (non-working) and tried its keyboard, which worked perfectly with very extensive testing. So now the Japanese clone is back together with this new keyboard after modifying the case a bit, swapping some switches from the old keyboard to this new one, and swapping all of the old keycaps over (some switches and keycaps were missing from the new keyboard originally). The switches were the right height, but the legs didn't line up with the holes/pads of the PCB, so I dremelled them flat and soldered wires to each one which I then fed through the holes in the PCB, cut to length, and folded over + soldered. I also stole some chips from the dead board to replace the ones in this board that had broken legs and bodge wires previously. Everything appears to be working fine now.















    Last edited by Joudan; October 22nd, 2019 at 08:19 PM.

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •