Post by Alex Liggett on Sept 17, 2022 9:53:20 GMT
A member of this parish, knowing my love of such things recently sent me a box of treasures, amongst much else which were two dead HP-11Cs. The first was in only slightly average cosmetic nick but had obviously taken rather a hard knock to the head at some stage:
You can't really tell from this pic but the display was entirely black, and closer inspection revealed that the front glass of the LCD is shattered. RIP.
The second one was in dreadful condition, broken shell, missing battery door and battered to buggery, but it did appear to have an intact display. <rubs hands>:
More observant readers may notice that there's something different about this '11C', which didn't become apparent to me until I opened them up. Here's the first one:
It's in good condition inside, other than the busted display. The second one has quite major corrosion, which is probably not terminal:
I was briefly puzzled by the extra chip in the second one, until it dawned on me that it's obviously a 15C, not an 11. Well I already own 3 HP-15Cs and I don't really need a super ratty 4th one. But there's the potential here for a nice-ish 11C, so I took the plunge of swapping the displays over. To do this you have to cut away the melted over ends of the plastic stakes holding the PCB onto the front shell. There are 48, so it's quite the tedious task, especially when you have to do it twice. Once the PCB is free it is quite a quick and easy task to remove the display, as it is simply clipped to the front of the PCB:
The rubber mat sits between the keys and the PCB. The amount of crap on this one indicates that this was a hard working field tool. The display looked good, so 48 plastic stakes later, and quick swap of the displays and a temporary fit back into the case for a test:
Success! Now that I have the guts of a working 11C I decided to take things a bit further. I happened to have a tidy HP-12C Financial (these were produced in relatively enormous numbers and so are easy and cheap to acquire) front shell from a unit that donated its display to another dead 11C repaired for a mate a few years ago. The 12C has radically different functions, so I need to swap the keyboard faceplate over. I carefully removed the 11C one from its battered shell, and less carefully removed the surplus 12C faceplate. I took the opportunity to remove the rear label plate from the 11C, as it was beginning to peel off. So here's where I'm currently at:
Once I have the two metal plates glued back on, I'll do a dry fit of the PCB and a more thorough check to make sure the keyboard is OK (usually the other point of failure in 11Cs), and all going well I'll do some overclocking magic as described in a previous thread, then pop everything back together. I'll be sure to post an update when it's done.
No idea whether this is of interest to anyone, I'm mainly putting this out there to say that 'dead' HP-11Cs and 15Cs are rarely completely rooted unless the display is bust, so don't throw them away. Aside from anything else they're worth a surprising amount of money in working order.
You can't really tell from this pic but the display was entirely black, and closer inspection revealed that the front glass of the LCD is shattered. RIP.
The second one was in dreadful condition, broken shell, missing battery door and battered to buggery, but it did appear to have an intact display. <rubs hands>:
More observant readers may notice that there's something different about this '11C', which didn't become apparent to me until I opened them up. Here's the first one:
It's in good condition inside, other than the busted display. The second one has quite major corrosion, which is probably not terminal:
I was briefly puzzled by the extra chip in the second one, until it dawned on me that it's obviously a 15C, not an 11. Well I already own 3 HP-15Cs and I don't really need a super ratty 4th one. But there's the potential here for a nice-ish 11C, so I took the plunge of swapping the displays over. To do this you have to cut away the melted over ends of the plastic stakes holding the PCB onto the front shell. There are 48, so it's quite the tedious task, especially when you have to do it twice. Once the PCB is free it is quite a quick and easy task to remove the display, as it is simply clipped to the front of the PCB:
The rubber mat sits between the keys and the PCB. The amount of crap on this one indicates that this was a hard working field tool. The display looked good, so 48 plastic stakes later, and quick swap of the displays and a temporary fit back into the case for a test:
Success! Now that I have the guts of a working 11C I decided to take things a bit further. I happened to have a tidy HP-12C Financial (these were produced in relatively enormous numbers and so are easy and cheap to acquire) front shell from a unit that donated its display to another dead 11C repaired for a mate a few years ago. The 12C has radically different functions, so I need to swap the keyboard faceplate over. I carefully removed the 11C one from its battered shell, and less carefully removed the surplus 12C faceplate. I took the opportunity to remove the rear label plate from the 11C, as it was beginning to peel off. So here's where I'm currently at:
Once I have the two metal plates glued back on, I'll do a dry fit of the PCB and a more thorough check to make sure the keyboard is OK (usually the other point of failure in 11Cs), and all going well I'll do some overclocking magic as described in a previous thread, then pop everything back together. I'll be sure to post an update when it's done.
No idea whether this is of interest to anyone, I'm mainly putting this out there to say that 'dead' HP-11Cs and 15Cs are rarely completely rooted unless the display is bust, so don't throw them away. Aside from anything else they're worth a surprising amount of money in working order.
