Apple II Europlus - No Graphics

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Joined: Jun 15 2016
Posts: 6

Hi All,

First off, I have to say it is great to see there is a healthy community for the old Apples out there! I am a new member and recently found a Europlus (I am in Australia). I learned to code on one of these back in the early 80s.

I have it up and running and seem to go well except for one thing, it does not display graphics, the screen just goes blank whenever graphics should be shown, although text mode is fine. I found a couple of old games that should display graphics, but don't, although the program is running fine just not showing graphics. The weird thing is however when I reset the computer while that program is running, the graphic screen flashes up for a moment before the machine resets. In that brief moment, the graphics is displayed perfectly. From memory this machine will only display B&W without a PAL colour card. I had a read through the forums but can't see if anyone else has had a similar issue.

My setup is an Apple II Europlus with 16k Lang card, original disk drive controller with the first type floppy drive. My monitor (a 16" LCD TV that displays either PAL or NTSC) and is showing that PAL is detected when I start the machine connected via an "AV" cable, and I see the normal Apple ][ test on boot and all text programs work fine.

I have to say it has been long time, and I am "very" rusty with regards the Apple II. I hope I am not doing something dumb, but is there something I am missing here? Does any one have any suggestions?

Any help greatly appreciated.

Regards,

Damien

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speedyG's picture
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Joined: Nov 16 2011
Posts: 2406
Re: Apple II Europlus - No Graphics

Hello Brightfall,

first of all welcome to the community.

Second: there are some members out there in downunder like MarkO.
Maybe it's a good idea to try get contact by phone and find out how far distance between you both really is.....
( sometimes in such cases a meeting at a can of beer or a cup of coffee solves miracles.... )

So at the moment lets resume the facts....
at least the computer does make the graphics at short period of time and also displays it....
so it ddoes not seem to be an issue related to RAM or Hardware ourside of the Apple....
It seems rather more that the problem is related to the softswitches that turn on graphics
but don't perform that in normal mode....

there may be several different kinds of reasons for that behaviour...
therefor i'd recommend to get familiar with ADT at the ADT page:
http://adtpro.sourceforge.net/
that permits you to create testdisks from the images at:
http://mirrors.apple2.org.za/ftp.apple.asimov.net/images/disk_utils/diagnostics/

The target would be to detect if all graphics are affected or if it affects to LORES graphics or HiRes graphics only ( examining also "mixed mode"...)

that testing would narrow possible sources of trouble down...

in one case it might be one of the 74LS02 chips at position A12, A14 or B13 ( 3 x )
or the 74S11 or 74LS11 at position B12 (1X )
or one of the 74LS174 at position B5 or B8 ( 2 x )
or the 74LS08 at B11 ( 1 x )
or the 74LS74 at position A11....... ( 1 x )

sincerely
speedyG

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the second part includes less friends but a lot more joy on life....

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Joined: Jun 15 2016
Posts: 6
Re: Apple II Europlus - No Graphics

Thanks speedyG,

I will hunt around and see who I can find here in Aus. Another member pointed me to the Apple II Oz site which I had not yet discovered, so all good.

I do have a Floppy EMU disk emulator so have found a diagnostic program, and sure enough it runs a hi-res gr test, and just as it draws the screen it goes blank, but it does briefly flash a quick image up but disappears. Its looked OK for the instant it was there.

That made me think I should be able to test the problem with a program, so I typed in a program to draw stuff on the lo-res screen. The program starts by changing to GR, and as soon as that happens the screen clears and I see nothing. I confirmed that GR should leave the bottom 4 lines free, but all text in the mixed mode is gone too. I can type in the TEXT command and everything goes back to text mode as normal.

My quick tests seem to indicate that when I switch to any graphics mode, nothing, neither text nor graphics is displayed until I switch back to TEXT mode.

So I don't know if that helps narrow it down.

If It is looking too hard to resolve I will see if I can find some local skills. Thank for the guidance, much appreciated!

Regards,

Damien

speedyG's picture
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Joined: Nov 16 2011
Posts: 2406
Re: Apple II Europlus - No Graphics

Hello Damien,

it seems to confirm that the problem is related to the so called :
soft switching to graphics....
that brings us back to the list of chips that i listed above....

those chips are not very expensive ( average cost less then 1 buck per chip )
so if you would change all chips listed above the cost will be average total of less than 10 bucks....

They are also all easily available at local electronic supply shops in Australia
( even at those that offer online ordering and shopping )...

so without skills it might be cheapest and easiest to just swap out that bunch....
and if you want to detect the really bad guy - then swapping chip by chip back till mistake re-appears...

speedyG

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In early days I had a lot of money but no time - now I have no money but a lot of time....
the second part includes less friends but a lot more joy on life....

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Joined: Jun 15 2016
Posts: 6
Re: Apple II Europlus - No Graphics

Hi speedyG,

The good news is that I have a working II+ motherboard which I bought for parts, so I have a source of chips to switch with, so I have replaced all those in the list as you suggested, one by one, but sadly to no avail.

I did some hunting around and found a couple of PDF manuals online re troubleshooting, and had a look at a couple of possible solutions there too, and switched out a couple of chips they suggested, but again no change.

I have been watching the behaviour of this problem, and the screen definitely draws whatever I tell it, but then the whole screen immediately goes blank. In split mode graphics even the text disappears. It is almost like the monitor has been switched off until I type the text command. Changing to another GR mode once the problem is triggered, the screens stays blank. Some sort of signal to the monitor is still there though, otherwise I would see a Lost Signal message on my TV.

Regards,

Damien

speedyG's picture
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Joined: Nov 16 2011
Posts: 2406
Re: Apple II Europlus - No Graphics

Hello Damien,
did you while changing the IC's also practice "reseating" several times
to get rid of oxydation inside of the sockets ?

speedyG

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ggb
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Joined: Mar 13 2012
Posts: 31
Re: Apple II Europlus - No Graphics

Hi Damien,
based on your results after swapping Speedy's suggestions, look to replacing the 74ls257 at A8 and/or 74ls194 at A10

GeoffB

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Joined: Jun 15 2016
Posts: 6
Re: Apple II Europlus - No Graphics

Hi All,

Thanks again for all the help.

I will swap out the new chips as suggested, and then reseat all of those and see how that goes.

Regards,

Damien

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Joined: Jun 15 2016
Posts: 6
Re: Apple II Europlus - No Graphics

Hi All,

Well the solution to this problem is certainly illusive, as no luck with those suggestions. I have replaced a fair number of the A and B row chips now, and reseated all chips in those rows three times just to be sure. There has been no change in behaviour.

Any other thoughts?

Regards,

Damien

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Joined: Dec 4 2015
Posts: 43
Re: Apple II Europlus - No Graphics

So you say the HGR graphics displays briefly then disappears? After it disappears, if you disconnect the AV cable and reconnect it, do you again see the graphics momentarily?
Does it look normal for that brief instant, not rolling vertically or horizontally? I'm thinking some kind of signal incompatibility. On most modern displays, if the signal is incompatible
it will mute the video. Is there any kind of options in the menu of your display to change?

Larry G

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Joined: Jun 15 2016
Posts: 6
Re: Apple II Europlus - No Graphics

Hi Retrogear,

Thanks for the suggestion, but sadly no, the display stays off if I try what you suggest. When I unplug the TV, it shows a loss of signal message, and that remains when I connect the AV again. It looks like the Apple is not sending an AV signal at that point??

To answer your other question, the monetary view of the GR or HGR image is solid, not scrolling, etc.

The problem seems to be with the Apple not the display from what I can tell.

Now I have a PAL card and have plugged that in, and it works correctly, so the problem is definitely on the motherboard somewhere. At this point I have switched out all the A and B row chips. It is definitely a weird problem.

Regards,

Damien

speedyG's picture
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Joined: Nov 16 2011
Posts: 2406
Re: Apple II Europlus - No Graphics

Hello Damien,
the results are correct diagnosed, but the conclusion might be wrong....
the miss of the signal at the 16" TV is not because the Apple does not send it -
it's result from the slight shift missing the correct frequency
(The Apple does not send precisely that what is defined to be PAL-signal..... )
and the second problem is a slight shift at the lervel of the sync signal at the
AV-adapter.....
the other problem of display of empty white blank screen is a problem of the
softswitch at the Apple - thats really a problem of the mainboard....
and it's a strange effect, that the "softswitch" problem disappears if a PAL-card is inserted.

sincerely
speedyG

__________________

In early days I had a lot of money but no time - now I have no money but a lot of time....
the second part includes less friends but a lot more joy on life....