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Old 7th Jan 2021, 11:28 pm   #74
SiriusHardware
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Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,484
Default Re: Non-working Commodore PET 3016

I suspect the browning just means that the chip has been separately reworked at some point, the only other reason it would go brown like that is if the chip was running very hot for a very long time.

If you've never used those desoldering tools I suggest you do not start on the PET but practice on a scrap board, ideally a double sided board with the ICs soldered into it like the one in the PET.

The problem with that manual type of solder sucker is you usually have to retry each joint a few times, putting more solder back on the pad each time so the sucker has a decent amount of solder to go at.

The more heat you apply and the more often you apply it, the greater the chance of damaging the pad, the PCB, or breaking down the bond between the pad and the PCB. Knowing how much heat you can get away with for how long is a matter of experience, that's why I suggest you practice on something non-critical before you try to tackle anything on the PET.

Edit: Crossed with Mark.
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