More Commodore PET drives - more help?

[Gordon JC Pearce]

Dave Dunfield wrote:

> Replaced ANOTHER 4116 DRAM in a CBM 2001-N last night - this makes 7 or 8 I've
> changed so far - symptoms are always the same - amount of memory "found" by BASIC

They were always a favourite for dead ZX Spectrums.  I got good at 
identifying the failing chip just by looking at the screen - there would 
often as not be a one-pixel "pinstripe" across the screen.  The "2" in 
the copyright message was good, if the machine managed to get as far as 
displaying it.

Since the chips ran *slightly* warm normally, and either ran very hot or 
completely cold when they failed, I could identify them by feel - hold 
the back of my hand above the memory to make sure one isn't clearly red 
hot, then feel each one in turn until I found the knackered one.  Wasn't 
often wrong, either.  Dead good, that.  The things that impress you when 
you're a spotty teenage computer geek.

Gordon.