Re: Apple II- Repair

[Linards Ticmanis <ticmanis@coli.uni-sb.de>]

Bryan Parkoff wrote:

>     I would like to discuss this matter with you personally about the Apple
> II/II+'s mainboards.  I understand that you prefer me to post in the
> newsgroups because you don't know the answer.  I do not mean to bother you,
> but I would like to ask with your best knowledge as possible.

Hi Bryan,

I still prefer the group. If the messages are in the group, then Google
will archive them and other people can make use of it in the future.
Also other usenet readers can drop in and add useful comments. There is
not one advantage to using private mail for this, so I don't really
understand why do you insist on it? Please let's move the discussion
back to the group where it belongs. I mean we are not writing love
letters to each other. ;-)

> I have both II/II+'s mainboards.  I did already swap ROM and RAM chips
> between both mainboards.  Both chips are working fine on the II+'s
> mainboard, but not II's mainboard. 

Ok that means they are OK then.

> Then, I did swap 74S115N chips.  II+'s
> mainboard uses II's chip that works fine.  II+'s chip does not work on II's
> mainboard.  It is very strange.  I have already done swapping before you
> posted second message in the newsgroups.

Well then those chips are OK, then next step would be exchanging the
other 74... chips and the processor. If the II board has 48K RAM then
you can try exchanging the RAM chips too (the II+ mainboard always has
48K, but the II doesn't always, it can have between 4K and 48K.)

Exchange all chips - not just the RAM, ROM, and 74S115.

Especially exchange *the power supply*!!! I think this is more likely to
go bad than many other parts.

>     If my theory proves that II's mainboard is bad, it will be almost
> impossible to repair II's mainboard.

You can look if there are cracks visible. The quartz and the basic video
circuit must be working OK , otherwise there wouldn't be a stable
picture on the screen as you describe. If the board is not cracked, it
is unlikely that the board itself is damaged.

>  My question is--Does II's mainboard
> always have with ROMs monitor prompt and Integer BASIC prompt that it never
> has AppleSoft BASIC, but II+ always has with ROMs AppleSoft BASIC prompt
> that monitor prompt and Integer BASIC prompt are hidden.

Yes - by definition this is *the* difference that makes a II+ into a II+.

>  I know that DOS
> 3.3 Master will load Integer BASIC or AppleSoft BASIC into memory.
>     It will be much easier for me to swap ROMs only because I want to work
> with original Woz's assembly routines and revised assembly routines.

Then you can simply swap the ROMs and leave everything else alone.

>     I am told that II's mainboard and II+'s mainboard are not the same.  Is
> it true?

Most of the time but not always. Most II's have a board that can take
between 4K and 48K RAM, and most II+ have a board that has always 48K
RAM. But the important difference is the ROM's and the label on the case.

>     I notice that you are from Germany.  Do you live near the company,
> ///SHH Systems?  Joachim Lange is the director of this company that he
> manufactures the products such as BlueDisk etc.  I am only curious.  Thanks
> very much.  Smile...

Sorry to say, I have never heard of them. What city are they in?

I live at Saarbr�cken in the southwest, very close to the French border.

Greetings,
-- 

Linards Ticmanis

 The Master said, "The business of laying on the colors follows the
preparation of the plain ground."