+- HP Forums (https://www.hpmuseum.org/forum)
+-- Forum: HP Calculators (and very old HP Computers) (/forum-3.html)
+--- Forum: General Forum (/forum-4.html)
+--- Thread: Another 1MB FRAM-71 Upgrade (/thread-4655.html)
Another 1MB FRAM-71 Upgrade - cruff - 09-05-2015 08:38 PM
I've just finished adding a second 512KB FRAM chip to my FRAM-71. For anyone else doing this, here are some hints.
- The upper chip's pins must be bent somewhat more than 90ยบ to make contact with the lower chip's pins.
- Use bright lighting or you can't determine anything worth squat.
- Use magnification - very important!
- Flux is your friend - extremely important!
- Make sure your soldering iron tip hot enough to be able to melt solder quickly.
- Continuity test the results pin by pin.
- Don't break off pin 6. Had to do some field surgery on the chip. :-)
I made a first pass with a head mounted magnifiers and a fine tip on my soldering iron, but it wasn't working. I had to make a second pass at it this this afternoon. This time I used my DSLR with a macro lens and remote live view mode on my lap top screen to examine the results. Here is a snap of the setup. The FRAM-71 board was clamped in the vise where the solder braid is sitting.
[attachment=2497]
Here is a close up of the pin 6 repair. Used a small milling bit in a Dremel drill press to gain access to the buried pin.
[attachment=2498]
RE: Another 1MB FRAM-71 Upgrade - brickviking - 09-05-2015 09:08 PM
(09-05-2015 08:38 PM)cruff Wrote: I made a first pass with a head mounted magnifiers and a fine tip on my soldering iron, but it wasn't working. I had to make a second pass at it this this afternoon. This time I used my DSLR with a macro lens and remote live view mode on my lap top screen to examine the results. Here is a snap of the setup. The FRAM-71 board was clamped in the vise where the solder braid is sitting.
Here is a close up of the pin 6 repair. Used a small milling bit in a Dremel drill press to gain access to the buried pin.
Nice work! I couldn't have done that myself, my tools don't amount to much more than a soldering iron (25W), pliers, several screwdrivers (one with a LED light), a 10 Metre measuring tape, and the all-important hammer.
Oh, and a container with about 150 screws from hard drives...
(Post 18)
Regards, BrickViking
RE: Another 1MB FRAM-71 Upgrade - Dave Frederickson - 09-05-2015 11:01 PM
(09-05-2015 08:38 PM)cruff Wrote: Here is a close up of the pin 6 repair. Used a small milling bit in a Dremel drill press to gain access to the buried pin.
(Strange that your pic isn't in the quote)
A drop of 5-minute epoxy will ensure that the pin doesn't break off again.
Dave
RE: Another 1MB FRAM-71 Upgrade - brickviking - 09-05-2015 11:19 PM
(09-05-2015 11:01 PM)Dave Frederickson Wrote: (Strange that your pic isn't in the quote)
I prefer that, though you do then have to refer to the original post. It reduces the chance that 45 copies of the image get loaded if the thread's particularly long and everyone quotes. Our pages take long enough to load, even considering most of us are probably on DSL or better.
(Post 19)
RE: Another 1MB FRAM-71 Upgrade - rprosperi - 09-06-2015 12:12 AM
(09-05-2015 08:38 PM)cruff Wrote: I've just finished adding a second 512KB FRAM chip to my FRAM-71.
Nice work, thanks for the pics and notes. This puts you in rare company! I think Dave and Hans are the only others that have accomplished this tricky upgrade.
RE: Another 1MB FRAM-71 Upgrade - cruff - 09-06-2015 12:23 AM
(09-05-2015 11:01 PM)Dave Frederickson Wrote: A drop of 5-minute epoxy will ensure that the pin doesn't break off again.
There was nothing left of the external pin left to break off, and I only removed the part of the case that is above the internal portion of the pin, the wire is soldered to that part of the pin in a well in the plastic.
RE: Another 1MB FRAM-71 Upgrade - Dave Frederickson - 09-06-2015 02:31 AM
(09-06-2015 12:12 AM)rprosperi Wrote: I think Dave and Hans are the only others that have accomplished this tricky upgrade.
Yoda: "No...there is another..."