How do I format an HP-48GX FRAM Card?

[orodionov]

Hey Guys. I did design and sell those FRAM cards back in 2016. It is remarkable for me to see it is still in use. It was PITA to design and assemble them. Design was tricky because FRAM required level shifting. Level shifting chips, on the bottom of the card, had to be controlled in a way that fits the timing and protocol of the HP48 Assembly was complicated because chips have very fine pitch and my assemby technique to flow the solder included the electrical pan)))))
Most likely, the issue is cold joint in one of the pins. Solution could be to re-flow the card or touch every pin with the solder gun

[JDW]

(08-02-2024 12:43 PM)orodionov Wrote:  Hey Guys. I did design and sell those FRAM cards back in 2016. It is remarkable for me to see it is still in use.

First of all, I wish to humbly thank you for the private messages you sent to me through eBay and for posting here. I think it’s an amazing testament to the wonderful person you are for having chimed in after all these years. And yes, your card did last quite a long time.

I use my calculators at the office and I’m at home for the weekend now, but on Monday I will use my heat gun to re-flow the solder, as that would be a more accurate way of doing it than touching each pin with an iron, which possibly could cause accidental bridging. I will then report back if that helps.

If it doesn’t help, that means one of the chips must’ve died for some reason.

[JDW]

I applied flux and then used my heat gun set to 360°C, flow set to 2 (low), and reflowed all the legs of everything on the component side. I checked every connection under a microscope and used a small soldering iron tip to touch any leg that I couldn't see well or doubted. I then let the card cool and used 100% IPA to clean off the flux. After that, I let the card dry out a few hours.

I inserted the card into Slot 1. When I pressed ON, I got the same WARNING, INVALID CARD DATA error text. I then tried PINIT again, and this time it was uneventful. After that, I powered OFF and then ON. Surprisingly, I am not getting the WARNING anymore!

I then checked the 48G User's Guide and found "Port RAM Test." I gave that a try:

1. Properly seat card (already done)
2. Set DIP SW to Read/Write (already done)
3. Turn ON calculator.
4. Press-and-hold ON.
5. Press then release "D"
6. Release ON. The calculator beeped once, and then vertical lines appeared at far left, far right, and in the very middle of the display.
7. Press then release up-arrow key. The screen was filled with random pixels, and then I saw something change in the upper left part of the screen, and it then ended by saying:

RAM1 OK (showed only for a brief flash of maybe 200-300ms, then vanished)
RAM2 90000 (appeared in place of "RAM1 OK")
(vertical line down the middle of the display)
Nothing was inserted into Slot-2, so I assume the above info shows all is well.

8. Press-and-hold ON.
9. Press then release "C"
10. Release ON. (Got me back to normal calculator operation.)

I did that twice, and it gave me the same thing.

After that, I did the following test:

1. Put a number on the stack.
2. Left-Arrow and "2"
3. Pressed "A" corresponding to "PORTS"
4. Pressed "B" corresponding to :1:
5. Right-Arrow and "+" (to get : : double colons)
6. Typed "1" (for slot 1)
7. Pressed Right-Solid-Arrow (to move past the 2nd colon)
8. Typed "BBB" (just a random name)
9. Pressed "STO" (then "BBB" appeared as a softmenu)
10. Pressed "A" corresponding to "BBB" and it returned the number I had previously on the stack.

I then did this:

1. Left-Arrow and 2
2. "1"
3. Press "B corresponding to PVARS
It then displayed this:

{ :1: A }
131048.5

After deleting my lone variable and rechecking, it shows:
131072

This again is showing proper operation of the FRAM card in Slot 1.

I then did MERG, followed by 1 & PVARS, which then said "SYSRAM".

Meta Kernel does not load, which means the card ended up getting wiped. At least I am assuming that. So I will need to reinstall that and see how it goes. But for now, the above tests show something positive!

[rprosperi]

Great news, and thanks for the detailed notes on both your repair procedure and the test steps your followed to verify it, both helpful for future readers.