Apple 2c IIc video issue

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Apple 2c IIc video issue

Hello!

I am having a strange issue with my Apple 2c. It will boot up fine, but after it warms up which takes about 30 seconds the text starts to get distorted and fuzzy.  It keeps getting worse until it can't be read at all. Turning it off and on again does nto effect it unless I let set unplugged for 5+ min then it works fine for another 30 seconds. I can still type and run commands fine, I just can't read/see anything. It is a rev 2(0) board with no mods. I looked at the board and did not see any caps leaking. I did swap the 6 biggest ones to see if that was it, no luck. I also unplugged the floppy, and it makes it take longer before glitching out, maybe 2-3 minutes vs 30 seconds, so that makes me wonder if it is in the power board.

Any ideas?? I have uploaded a video so you can see the distortion. https://youtu.be/3pZoFFXiKlo

Thanks!! 

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First thing I would do is

First thing I would do is swap out the power supply.

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I would put a meter on the

I would put a meter on the power supply and see if the voltages change when the problem starts to appear.

 

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Thanks for the replies! I don

Thanks for the replies! I don't have another power board to swap, or are you thinking the external 15v supply? I tried the meter a bit, but was not seeing any change, but I will try again, it was hard to check all the connectors from the PSU board, it has a cartridge like connecter with quite a few to watch... I have attached an image

 

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PSU pinout: I did just find

PSU pinout: I did just find this. 

So it looks like most are ground pins.

 

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Hey,

Hey,

 

An update: Still no luck. I now have changed all but a few caps. The PSU voltage to the board seems to be stable and stays the same before and after. It's not perfect, but I assume close enough. 12.3V, 4.89V, and -11.8V. 

 

Any other ideas?? Oscillator somewhere?

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