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Wavy Display on Apple IIc

M

MrDOS

Member
Joined
Mar 28, 2011
Messages
12
Location
Tifton, GA
I have an Apple IIc that is working but the monitor output has a slow wiggly wave that passes through it.
Sometime the vertical hold will flip a few times as well.
Also, the video seems condensed horizontally.
Any ideas what could cause this?
 
You know, I haven't personally seen this problem before, but I've heard of it from someone else just recently. I'm not sure what it is, but I'd start by checking to ensure the power supply is working properly. The //c kind of has two power supplies - one is the external brick-on-a-leash that supplies 12v to the internal power regulator, and then the internal power regulator circuit converts that to the 5v (and others) needed in the computer. Check the voltage inside the computer at one of the chips, and be sure you are actually getting a clean 5v.

Another possibility is a cracked solder joint in the video section - try wiggling everything. On the IIe and other machines, there is a video level pot that causes weird things if it gets dirty. If the //c has it, try pressing on it.

Of course, this all assumes that the problem is in the //c, not the monitor - but I'm sure you tried that already :D

-Ian
 
The thing is, I don't believe this is a problem with the monitor, but with the computer itself - the last one I heard of was. If it was the monitor, I can tell you exactly how to fix that - those are easy :)

-Ian
 
Thanks, I tested the monitor on my IIe and it is working fine so it must be a problem with the IIC.

RetroHacker_ said:
Check the voltage inside the computer at one of the chips, and be sure you are actually getting a clean 5v.

Another possibility is a cracked solder joint in the video section - try wiggling everything. On the IIe and other machines, there is a video level pot that causes weird things if it gets dirty. If the //c has it, try pressing on it.
Click to expand...

I will probably take a look at it tonight.

I found this picture if it might help with any recommendation.
http://moparx.com/files/images/iic_disassemble2.jpg

By the way, the problem does not show itself if using an RF modulator and TV.
 
MrDOS said:
By the way, the problem does not show itself if using an RF modulator and TV.
Click to expand...

OK. So, then that probably rules out the power supply in the computer then, if it works with the modulator. Can't hurt to check it though. Obviously, check the jack itself. I've seen several on IIe's where the center pin had actually cracked off the board - those didn't display these symptoms, that was just a no video/intermittent video problem.

Having never seen this problem in person, it's hard to say what it is.

-Ian
 
I took it apart and bent the video out center pin connector from the inside so that it would make a tighter connection.
I would say that it resolved the problem at least 80%
Any other ideas?
 
i would resolder the joints on that video out connector or possibly the video out connector needs to be replaced or cleaned.
 
Try a different video cable. I have one cable here that reproduces that wavy line pattern you describe on every system and monitor combination I have here. Also, make sure you clean all the tarnish off the video jack contacts inside the IIc.
 
I had 2 IIc screens with the wavy image occuring. It turned out that the pots at the back were just oxidiesd. After removing the rear panel of the screen, and removing the grey thumbsticks on the pots I put a bit of WD40 in there and then turned each of them for 30 seconds back and forth. Now both of my screens don't have the wavy distortion.
 
I can confirm the solution from mkusanagi worked for me aswell. thankyou. The apple iic i purchased had been in long term storage for many years. The iic display was alittle wavy and had a vertical hold issue when first switched on. It wouldnt stabilise properly. I fix do following. Unplug the monitor power cord first completely. Now remove the 2 screws on back panel followed by the square plastic back panel. You will see 3 grey potentiometers that are used to adjust the picture. Gently remove the 3 grey covers from the potentiometers by pulling them towards you. We now need to lubricate the potentiometers moving parts. To do this, turn monitor upside down and spray alittle deoxit (or WD-40) carefully into each potentiometer. Placing the monitor upside down allows the dexit (or WD-40) to flow into the Potentiometer moving parts. Now turn each potentiometer left and right for 30 seconds each to spread the lubrication. Thats it. Now do the reverse to put it back together and thats it! Hope this helped you friends :)
 
This is great info! I just recently acquired my first Apple IIc, and I'm sad to report that my display is slowly waving / wobbling. I've tested the IIc with a few other "known good" composite monitors without any waving, so I'm reasonably sure it's the IIc monitor at fault here.

@bongostar777 - may I ask if your "wobble" looked like what I'm seeing? As someone possessing only amateur-level electronics repair skills, I would be DELIGHTED if all it takes is some WD-40 to fix mine!

Huxley
 
I wouldn't use the regular WD-40 for pots, it's kind of aggressive. Rather use mild contact cleaner (Deoxit F, Kontakt 61) which leaves a protective film behind.
 
powerlot said:
I wouldn't use the regular WD-40 for pots, it's kind of aggressive.
Click to expand...
Do you have a source for that? WD-40 is perfectly fine for cleaning contacts or even whole pcbs etc. It is only known to cause long-term damage to rubber, but not to anything else.
 
Timo W. said:
Do you have a source for that? WD-40 is perfectly fine for cleaning contacts or even whole pcbs etc. It is only known to cause long-term damage to rubber, but not to anything else.
Click to expand...
The only source I have is that other techs have told me that when I asked around ... if it's wrong I'll gladly revise that assumption.

The reason was that it will dissolve / wash out all the lubricants which could make the pot vulnerable or scratchy in the long run
 
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