Graphics Error in II Plus

12 posts / 0 new
Last post
Offline
Last seen: 3 months 4 days ago
Joined: Jun 26 2018 - 03:37
Posts: 1
Graphics Error in II Plus

Hello!

In the past few weeks, I acquired an Apple II Plus that seems to have a graphics error. Whenever I attempt to boot the computer, vertical lines appear instead of the normal startup screen. I don't know if a chip is fried or what. I've added a high resolution image of the motherboard below for reference. Any help is appreciated!

Thanks
Kevin

P.S. - I should add that I'm an amateur when it comes to pre-mac era Apple machines and this is my first Apple II.

speedyG's picture
Offline
Last seen: 1 hour 57 min ago
Joined: Nov 16 2011 - 07:45
Posts: 2484
At beginning:

At beginning:
1. the clock crystal is wrong ( position A1 ) it should be 14,318 !
2. All RAM-chips have been replaced ( probably with several damaged ones ? )
none of that chips have been certified by Apple ( small Apple Logo printed on chip )
Also all the RAM chips are slowest timing spec ( -3 )=300 nanoseconds
should be instead at least (-25) =250 nanosecondes
I recommend to read and follow dignostic instructions from my site at:
http://www.appleii-box.de/D04_resurection.htm

Online
Last seen: 20 min 41 sec ago
Joined: Dec 20 2003 - 10:38
Posts: 368
Your RAM chips should be fast

Your RAM chips should be fast enough. Apple used that same speed in lots of Apple II Pluses.

Generally with these computers I've found that the most common problem is oxidation of the chip legs. They lose good contact with the socket. Lifting up the chips in the socket and pushing them back down re-establishes contact. (with the power off) If that doesn't do it then it's time to look further.

speedyG's picture
Offline
Last seen: 1 hour 57 min ago
Joined: Nov 16 2011 - 07:45
Posts: 2484
Wayne wrote:"Your RAM chips

Wayne wrote:
"Your RAM chips should be fast enough. Apple used that same speed in lots of Apple II Pluses".
.

Sorry BUT THAT'S NOT COMPLETE CORRECT.
all 300 Nanoseconds is critical
1. Lots of RAM-chips are slight faster than their specs.
2. That was also reason why Apple tested the used RAM-chips in factory.
4. Apple certified correct access-speed by stamp of color label with Apple-Logo on top of tested chips !
the chips on this board have not been tersted but changed in later time !

Online
Last seen: 20 min 41 sec ago
Joined: Dec 20 2003 - 10:38
Posts: 368
Apple bought from a lot of

Apple bought from a lot of manufactures, wherever they could get the best deal. They put the stamp on so they could charge more. Apple RAM was well known for being over priced. It was also well known for being less reliable than almost any other. Maybe being as good as Apples RAM isn’t that good a thing given it’s reputation.
Reseating chips is usually the first thing to try on an Apple II. Wholesale chip replacement is usually a little down the road.

speedyG's picture
Offline
Last seen: 1 hour 57 min ago
Joined: Nov 16 2011 - 07:45
Posts: 2484
even nowadays in the period

even nowadays in the period of"fakenews" and the era of trump, facebook and twitter
there is a slight difference between rumors and historic facts....

besides: why not start with the clocking crystel like i recommended ?
with wrong crystal entire timing at that mainboard won't work correct....

Offline
Last seen: 22 hours 58 min ago
Joined: Aug 24 2013 - 11:46
Posts: 47
Apple II Crystal Markings/RAM access speeds

The marking on the top (1970001) appears to match that used by Apple for the crystal in an Apple II. The part 197-0001 is listed as a Crystal, 14.318630 Mhz in the Apple Technical Procedures for the Apple II.

https://archive.org/download/ATP_87/ATP_Apple_II.pdf (pages 46 and 47)

My understanding of the clocking of this model of the Apple is that the video is derived from that crystal. As the video appears to be stable, it would be unlikely that there is an issue with the crystal.

In regards to the RAM, some reading indicates that the -3 could possibly stand for a 250ns access time.

http://www.minuszerodegrees.net/memory/Texas%20Instruments%20-%20Interchangeability%20Guide.pdf
(page 4)

National Semiconductor's version, the MM5290, seems to use the -3 to indicate a 200ns access time.

http://www.citylan.it/wiki/images/f/f4/Mm5290.pdf

Note, I just opened a II+ today with Apple stamped RAM, with a -3 extension. They are marked:

Mostek 8243 (or 8244, or 8245)
MK4116N-3GP
Apple (apple logo) (R)

Lastly, in addition to SpeedyG's guide, there is also the following diagnosis guide, which also includes a link to Apple's service notes.

http://www.willegal.net/appleii/appleii-repair.htm

speedyG's picture
Offline
Last seen: 1 hour 57 min ago
Joined: Nov 16 2011 - 07:45
Posts: 2484
Hello ChristopherB

Hello ChristopherB,
any proposals to get that Apple II debugged, up and running
or just agueing here to be present ???

jwg1962's picture
Online
Last seen: 1 min 3 sec ago
Joined: Jan 29 2012 - 07:17
Posts: 214
speedyG wrote:Hello

speedyG wrote:
Hello ChristopherB,
any proposals to get that Apple II debugged, up and running
or just agueing here to be present ???

I would look at replacing the RAM chips in ROW C or maybe the F8 ROM first. RAM is the simplest so I would go there first.

The other thing you can try is looking at this.

ftp://ftp.apple.asimov.net/pub/apple_II/documentation/hardware/misc/sams/Sams%20Computer%20Facts%20-%20Apple%20II%2C%20II%20Plus.pdf

As well as Speedy's page.

http://www.appleii-box.de/D04_resurection.htm

Thanks,
Jay

Online
Last seen: 20 min 41 sec ago
Joined: Dec 20 2003 - 10:38
Posts: 368
Had exactly the same screen

Had exactly the same screen on one II+. It was solved by reseating the text ROM. The ROM at the front of the motherboard.

speedyG's picture
Offline
Last seen: 1 hour 57 min ago
Joined: Nov 16 2011 - 07:45
Posts: 2484
Well just to mention two

Well just to mention two questions:
first: under normal conditions in such situation the screen would display 8 vertical bars....
what do you believe is the reason to display in this case 40 vertical bars instead ( 5-times more ) ?
and second: in case of such display... do you believe that access to that videoram is same as normal
or only fifth part of access time ( in nano seconds ) ?

Online
Last seen: 1 min 46 sec ago
Joined: Aug 4 2018 - 21:59
Posts: 85
Your crystal is correct you

Your crystal is correct you do not need to change it.  If the crystal was the wrong value you would not get a stable video image because all the video counting and sync are derived from the master clock.

Your DRAM has no speed issue at all, they are 200ns chips which is more than fast enough.

https://www.digchip.com/datasheets/parts/datasheet/321/MM5290N-3-pdf.php

That doesant mean that one or more is not faulty. Unfortunately the symptom you have can be caused by half the chips on the motherboard.
Without test gear or a complete set of known good chips the best you can do is reseat chips and look for bent pins or corroded leads on the chips.

 

Log in or register to post comments