Apple Color 100 - faulty brightness pot

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Apple Color 100 - faulty brightness pot

My Apple Color 100 works well, but the brightness pot seems to be faulty. The image is stable, but only at max brightness. Once I adjust the brightness down a bit it flickers and wavers a bit, then fades totally to black. If I fiddle with the knob I can get it back again, but it often is very finicky.

I welcome any thoughts on this. I haven't cracked it open yet -- it looks tricky to open, what with tabs and catches as well as the usual assortment of screws. I wonder, would that pot be a standard item?

 

 

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As with all potentiometers

As with all potentiometers over time, particulary the carbon wiper type, they get oxydized and/or the lubricant picks up dirt and airborne debris, causing your issue.

It's a good idea to simply replace it, or as a temporary fix (temporary being time-relative) you can use a spray cleaner such as a modern-day version of this stuff:  https://www.ebay.com/itm/292466669230/

 

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I opened it up and sprayed

I opened it up and sprayed out the potentiometer with compressed air, which made it work much better. Thanks for the suggestion. It also looks pretty easy to replace, so I'll pick up a new pot and solder it in when I get a chance.

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Apple Color 100 RGB Monitor

I was talking about my restoration of this monitor to a friend today and he suggested that I re-cap the entire unit. Does anyone know what effect that might have on it? Would it brighten the image? Would it strengthen the colors? I feel like the colors are a bit muted on it. But the whites are nice and white and the convergence looks real good. The test pattern I've tried has nice straight lines and squares. It's just the colors that seem not as bright as my composite monitor. They're sharper, for sure. Just not as bright or maybe I mean they aren't as saturated.

Any thoughts about re-capping?

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Only my opinion ...

It's only my opinion, and in this situation ...

If it ain't broke, don't fix it. :-)

Any component can fail, and at any time.  ... Or not.

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Follow macnoyd's advice. You

Follow macnoyd's advice. You could do more harm than good. My Apple II+ power supply smoked last week. I took it apart and it is just the safety capacitor that blew. The capacitor across the incoming AC that helps surpress RF. Anyway, Mouser still carries the same value safety X2 capacitor needed. I am just replacing that capacitor. I'll address other components in the power supply if it decides to take another dump in the future.

 

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macnoyd wrote:As with all

macnoyd wrote:

As with all potentiometers over time, particulary the carbon wiper type, they get oxydized and/or the lubricant picks up dirt and airborne debris, causing your issue.

It's a good idea to simply replace it, or as a temporary fix (temporary being time-relative) you can use a spray cleaner such as a modern-day version of this stuff:  https://www.ebay.com/itm/292466669230/

 

 

DeOxit fader is the modern spray.  You can find it in most Guitar stores since it works very well on electric guitar pots.

 

 

 

 

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Thanks for all the advice.

Believe me -- I don't want to do any work that I don't have to do. So, twist my arm and tell me not to re-cap the monitor. :-) Seriously, though, I think that's good advice. Leave well enough alone and fix problems as they arise. I'll put the new pot in the monitor and then go from there. I'm glad it works as well as it does.

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The new pot did the trick

I bought a new pot, but it physically didn't fit. Then I remembered that I had an Apple Monochrome monitor that I wasn't using and, sure enough, the contrast pot was identical to the one in the Apple Color 100. Swapped it out and not only does it work, but the image is a lot brighter and the colors look better.

Now I just want to find a place where I can buy a new pot that actually fits. Any thoughts?

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Post a photo of it and let us

Post a photo of it and let us know the R value.

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Photos of pots

Here's two photos I took of the pot. The 10k one is the brightness and the 500ohm one is the contrast.

http://www.theperryproject.org/uploads/5/0/5/6/5056725/img-0492_orig.jpeg
http://www.theperryproject.org/uploads/5/0/5/6/5056725/img-0491_orig.jpeg

 

 

 

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