tggzzz wrote: ↑Tue May 20, 2025 7:53 am
Zenith wrote: ↑Mon May 19, 2025 10:25 pm
tggzzz wrote: ↑Mon May 19, 2025 9:25 pm
I've little appetite for polishing a
boring 3.5 digit turd - and improving this is definitely whack-a-mole territory.
A working 3.5 digit bench DMM is OK. It doesn't run out of battery. If it doesn't work, it's in dustbin territory. However the processor is the same as used in better models, so if you are inclined to chuck it, remember me. I have an 8800A which I think has a shot controller IC.
It has a strange IC, part of a controller rather than an integrated controller like the ICL7126 family. FFI, see the manual.
Can't hold that against Fluke; clearly they were pushing the available technology.
Those 40 pin ICs were were used for control and display. They used them in several designs. There were a couple of versions and on the 8800A you have to add or remove a jumper, depending on which one is used. They are known to fail and are unobtainable as NOS.
I am sure the control/display IC has failed in my 8800A. I am wondering whether it can be replaced with board based on a Raspberry Pi Pico or Arduino. However, putting in a part from an 8000A is the easier option. There may be other parts worth retrieving from the 8000A, such as the voltage reference, stabistors and op amps.
So while the 8000A may be the black sheep of the Fluke family, they are not completely worthless. Furthermore, they are not very expensive or big and heavy, unlike vintage SAs. So taking a long view, the £5 you spent on the 8000A may not have been entirely wasted, the same as the £5 I spent on my declared non working 8800A. I don't think it's sensible to pay a lot for any of this old junk.
The Intersil 7106 & Co was used in a lot of DMMs. I've just given away a DMM with a 40 pin one in. More often they are mounted directly on the board and covered with a blob of something. I heard it was some sort of collaboration between Fluke and Intersil. Anyway, out of it came the 7106 which Intersil sold, to Fluke's annoyance, and there was a law suite.