Re: [Interest Check] FK-5001/9000 calculator replacement
Posted: 24 Feb 2021, 04:07
I’m also interested and curious if the calculator on the FK-8000 would be compatible with this project.
mechanical keyboard authority
https://ns1.deskthority.net/
engr wrote: 14 Nov 2022, 15:54 Any news on this project? I got an FK-9000, FK-5001, and FK-8000 with calculator issues... Would love to restore all of these.
The issue has nothing to do with capacitors. The conductive adhesive used to attach the display ribbon gets weak with age, effectively disconnecting the display. I've experimented with new adhesive but it's nearly impossible to apply it in a way such that no contacts are bridged but there's enough to keep the ribbon attached.engr wrote: 16 Nov 2022, 04:36 Sorry, best I can do is $50 try and replace electrolytic capacitors in the PCB and hope that was the cause of some calculator issues on Focus boards (which is what I am hoping to try within the next couple of weeks). Anything more complex than replacing components is currently beyond my comfort level.
"‘All functioning Focus boards resemble one another, but each broken Focus board is broken in its own way" - Leo Tolstoy on keyboards, probably, 1878.kelvinhall05 wrote: 16 Nov 2022, 05:24 The issue has nothing to do with capacitors. The conductive adhesive used to attach the display ribbon gets weak with age, effectively disconnecting the display. I've experimented with new adhesive but it's nearly impossible to apply it in a way such that no contacts are bridged but there's enough to keep the ribbon attached.
I have played with dozens of these calculators and they all fail in the same way lol. The problem you're describing is independent, though I still feel it's not related to capacitors, as the battery is ultimately on the same power rail as the 5v from a PC, just separated with a diode and resistor iirc (I don't have an original board on me to check). If it was a cap problem it would affect it all the time.engr wrote: 16 Nov 2022, 16:16"‘All functioning Focus boards resemble one another, but each broken Focus board is broken in its own way" - Leo Tolstoy on keyboards, probably, 1878.kelvinhall05 wrote: 16 Nov 2022, 05:24 The issue has nothing to do with capacitors. The conductive adhesive used to attach the display ribbon gets weak with age, effectively disconnecting the display. I've experimented with new adhesive but it's nearly impossible to apply it in a way such that no contacts are bridged but there's enough to keep the ribbon attached.
My FK-5001 has a glitch where the calculator works fine when using the keyboard plugged into PC, without a battery. When powered from a battery, however, it turns off once I enter too many digits. I am guessing it has something to do with PCB, and the capacitors seemed like a low hanging fruit to check first.
It's a shame these Focus boards have so many issues, because functionality-wise they are amazing.
Now that I'm looking at it... I don't understand how exactly this ribbon is electrically connected to the display in the first place. I am not seeing any connecting terminals on the LCD side, it's like it's just glued to glass. Are there just transparent strips of conductive glue leading from the ribbon conductors to the LCD?kelvinhall05 wrote: 17 Nov 2022, 00:30I have played with dozens of these calculators and they all fail in the same way lol.
The problem is PCB-side, not display-side. If you looked very close with light at the right angle you would see traces running in the glass.engr wrote: 17 Nov 2022, 01:51Now that I'm looking at it... I don't understand how exactly this ribbon is electrically connected to the display in the first place. I am not seeing any connecting terminals on the LCD side, it's like it's just glued to glass. Are there just transparent strips of conductive glue leading from the ribbon conductors to the LCD?kelvinhall05 wrote: 17 Nov 2022, 00:30I have played with dozens of these calculators and they all fail in the same way lol.
So this method will not work on the PCB side?kelvinhall05 wrote: 17 Nov 2022, 17:22 The problem is PCB-side, not display-side. If you looked very close with light at the right angle you would see traces running in the glass.
I don't have tools like that at my disposal so I couldn't try it. Don't see why it wouldn't work.engr wrote: 17 Nov 2022, 17:36So this method will not work on the PCB side?kelvinhall05 wrote: 17 Nov 2022, 17:22 The problem is PCB-side, not display-side. If you looked very close with light at the right angle you would see traces running in the glass.