Mac Classic Screen 'Wobble' (Caps?)

[techknight]

Just about everything deflection related...

 

[uniserver]

what happens is humidity/dust, Over the years can cause a potentiometer's internal mechanical connection to lose or interfere with its electrical connection, moving it back and forth mechanically restores a better electrical connection, and in the Classic and Classic II's fixes oddness, (sometimes)

Also what might be happening, Dust/humidity (COULD be) creating kind of a short, allowing abnormal RF into that specific circuit.

Showing abnormalities on the screen

 

[Tempest]

what happens is humidity/dust, Over the years can cause a potentiometer's internal mechanical connection to lose or interfere with its electrical connection, moving it back and forth mechanically restores a better electrical connection, and in the Classic and Classic II's fixes oddness, (sometimes)
Also what might be happening, Dust/humidity (COULD be) creating kind of a short, allowing abnormal RF into that specific circuit.

Showing abnormalities on the screen

Anything else I can do to clean it out so this doesn't happen again? Shoot an air duster into the back of it?

 

[uniserver]

i would use your air compressor and blast the whole thing out.

 

[CC_333]

And then once you've cleaned out the dust and grime, you should probably apply some sort of contact cleaner or lubricant to each of the controls (except maybe the width coil) to help prevent the problem(s) from reoccurring.

Also, if you haven't yet, you should recap it. That will spare you a lot of troubleshooting grief later on (and, given the age of those things, it's inevitable that something will fail.)

I'm glad it's working for now, though.

c

 

[Tempest]

And then once you've cleaned out the dust and grime, you should probably apply some sort of contact cleaner or lubricant to each of the controls (except maybe the width coil) to help prevent the problem(s) from reoccurring.
Also, if you haven't yet, you should recap it. That will spare you a lot of troubleshooting grief later on (and, given the age of those things, it's inevitable that something will fail.)

I'm glad it's working for now, though.

c

Are Classics noted for having cap issues? Were they part of the capacitor plague or were they before that?

 

[CC_333]

Are Classics noted for having cap issues? Were they part of the capacitor plague or were they before that?

Well, I don't really know for sure. It just seems like a good idea since many computers of that period are probably going to start showing signs of "capacitor plague" as time moves forward.
c

 

[Blinkenlightz]

If you're thinking of the era of electronics that had faulty caps when new, failing at staggering rates (early to mid 2000's), I'd say no - however the vast majority of Macs built in the early 1990s have caps that are failing now.

Plague? I suppose in a way, but these machines have all outlived their planned useful life. Component failure is unfortunate, but not necessarily a sign of faulty design.

 

[Tempest]

If you're thinking of the era of electronics that had faulty caps when new, failing at staggering rates (early to mid 2000's), I'd say no - however the vast majority of Macs built in the early 1990s have caps that are failing now.
Plague? I suppose in a way, but these machines have all outlived their planned useful life. Component failure is unfortunate, but not necessarily a sign of faulty design.

Yeah I was talking about those batches of bad capacitors that found there way into a lot of different computers. I think that started in the mid-late 90's though.

I should get these caps replaced eventually though.

 

[TheMacGuy]

I could have sworn that Cap Epidemic was in the early/mid-2000's. I remember because I have seen some computers from that era (non-Apples) with cap bursting and leak problems.

 

[Tempest]

Dang it, it's still doing it. Looks like I need to get it recapped after all.

 

[CC_333]

Yeah, as I understand it, the "Great Capacitor Plague" was in full bloom between about 2005/6 and 2008, with a few isolated incidents as early as 2002 and as late as 2010.

According to Wikipedia, my assertions are more or less correct.

I hope this clears things up a bit.

c

EDIT: I read the article, and the production of these bad capacitors did indeed start in 1999, so Tempest is right I think.

 

[techknight]

I started seeing the plauge in 2003ish or so. when the IBM towers (white towers, thinkcentre i think). Started failing with bad caps, causing weird issues such as missing RFID detector, and no post. LOL Something that machine never had or intended to have.