I have a iMac G3 from summer 2000, dv ruby 450mhz. One day I was testing old cds for games on it and it freaked out. I turned it off and then turned it back on and the screen was slightly pinched inwards. I can’t get photos until I’d say late June since I’m on vacation. How do I fix this?
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Weird Pinching on screen
- Thread starter sevenhundred
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Components are more than 20 years old.
There are adjustment steps in Apple's service manual for the iMac DV for screen geometry tweaking.
But, the components are more than 20 years old (I guess I already said that)
And, I think it is likely that something on the PAV (Power-Analog-Video) board has failed, or maybe the CRT...
There are adjustment steps in Apple's service manual for the iMac DV for screen geometry tweaking.
But, the components are more than 20 years old (I guess I already said that)
And, I think it is likely that something on the PAV (Power-Analog-Video) board has failed, or maybe the CRT...
I tried using the settings, so I’ve suspected a part on the pav board has gone dead. Apparently on one of the German forums there’s a part called a potentiometer that causes this when dead, but I don’t know what kind of potentiometer to buy
I expect that ALL of the various trim adjustments use a potentiometer of some kind.
That means that each adjustment has its own adjuster (individual pots on each adjustment).
But, I would also expect that the device which provides the output TO the potentiometer might also fail in addition to the potentiometer itself.
Maybe that German forum has some troubleshooting tips, too -- circuit diagrams will be quite helpful (but not always available for Apple products)
That means that each adjustment has its own adjuster (individual pots on each adjustment).
But, I would also expect that the device which provides the output TO the potentiometer might also fail in addition to the potentiometer itself.
Maybe that German forum has some troubleshooting tips, too -- circuit diagrams will be quite helpful (but not always available for Apple products)
You should really ask @MacTech68 over on the Collector’s section of the forum. He is very experienced with the older era stuff.
I personally did the component swap. It’s the one labeled VR901 and adjusts the B+ voltage of the CRT circuit.
It definitely helped to get a better geometry and I would recommend everyone to do the swap for a newer potentiometer. Only thing is you have to get deep into disassembling. That includes discharging the CRT.
I personally did the component swap. It’s the one labeled VR901 and adjusts the B+ voltage of the CRT circuit.
It definitely helped to get a better geometry and I would recommend everyone to do the swap for a newer potentiometer. Only thing is you have to get deep into disassembling. That includes discharging the CRT.
Alright, also what brand should I use? Is there a specific type of potentiometer? I’m new to all this so I dunno.
hmmm... What is your experience level with circuit board level soldering? (Or do you know someone with some soldering background?)
www.digikey.com
has just about anything that you might need. Amphenol brand is probably a good place to start, but best to try to identify the exact part that you need to replace, directly from the identification on the part, still in place on the circuit board.
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