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+--- Thread: 48G Destructive Teardown - EEVblog (/thread-8373.html)
48G Destructive Teardown - EEVblog - Dave Frederickson - 05-20-2017 03:18 PM
Fast-forward to 9:40.
"That's not a knife."
RE: 48G Destructive Teardown - EEVblog - d b - 05-20-2017 03:46 PM
Dave's in like Flynn. Winner Winner, chicken dinner!
RE: 48G Destructive Teardown - EEVblog - Han - 05-22-2017 05:51 PM
There are much less destructive ways to open an HP 48 and leave it still quite usable.
RE: 48G Destructive Teardown - EEVblog - cruff - 05-22-2017 11:52 PM
(05-22-2017 05:51 PM)Han Wrote: There are much less destructive ways to open an HP 48 and leave it still quite usable.
Unless Dave is trying to repair something, he doesn't take a lot of pains to keep the disassembly reversible. The 48 he took apart was one he was sent in a non-working state, as he couldn't bear to open up the previous one he received which was in nice shape.
RE: 48G Destructive Teardown - EEVblog - Han - 05-23-2017 01:52 AM
The other oddity about that calculator was the jumper between ROM and RAM chip. The calculator presumably got upgraded to 128KB, but such an upgrade never required anything more than a RAM chip replacement.
RE: 48G Destructive Teardown - EEVblog - Paul Berger (Canada) - 05-23-2017 02:34 AM
(05-23-2017 01:52 AM)Han Wrote: The other oddity about that calculator was the jumper between ROM and RAM chip. The calculator presumably got upgraded to 128KB, but such an upgrade never required anything more than a RAM chip replacement.
That jumper is on one of the address lines which would suggest a broken land on the board probably from removal of the original chip, but I think a shorter wire could have been used.
Paul.
RE: 48G Destructive Teardown - EEVblog - TomC - 05-23-2017 05:30 AM
The labelling on the ROM is unlike any I've seen.
TomC
RE: 48G Destructive Teardown - EEVblog - Eric Rechlin - 05-23-2017 07:58 PM
(05-23-2017 01:52 AM)Han Wrote: The other oddity about that calculator was the jumper between ROM and RAM chip. The calculator presumably got upgraded to 128KB, but such an upgrade never required anything more than a RAM chip replacement.
In the video he said that the original owner damaged a pad when doing the upgrade, so that's probably why there's a jumper wire. I also got the impression that the upgrader didn't know what he was doing 20 years ago when he did the upgrade, which is why it looks like a complete mess during the teardown (just look at the faceplate).