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Old Fluke Multimeters
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drtaylor:

--- Quote from: bd139 on August 10, 2017, 09:10:19 pm ---
AFAIK there's some software in it. The IC is a Mostek one rather than a Fluke ASIC and it supports similar dB functionality into defined impedances. The only thing it's missing that I don't really like is audible continuity but I've got an 8024 floating around for that.


--- End quote ---
The controller IC in the 8050 is a fully custom IC with A/D state machine control and if I remember correctly, the dB conversion was table driven with segment curve fitting. No software! This same approach was used on the 8920 TRMS Voltmeter, again no software. In the late 70s, high end system DMMs were being made with early uC and uP chips. There was an engineering manager at the time that was fighting against putting that new-fangled Microprocessor stuff into precision instruments. He was demoted in favor of a more forward thinker. The 8060A was notable as the first handheld that had a processor in it. It came out about a year after the 8050. I sat right next to the 8050 design team, but again, I had nothing to do with the 8050 design. I was finishing up my modest contribution to the 8920-8921 right before starting work on the 8060.
bd139:
Ugh that's horrible if it's state machine driven. I bet that was a ball ache getting that debugged.
lowimpedance:

--- Quote from: drtaylor on August 10, 2017, 04:02:35 am ---In a side note, one of my 8060s is really a prototype unit. It has a ceramic MAC chip, the RMS converter in a socket, and it has several kludges. The constant current output uses a LM334 and a couple of bodged resistors. There's also a couple of jumpers. This very likely is the oldest 8060 around as it is clear I was still fooling with it.

--- End quote ---
Would be a nice addition to the thread to see some pictures of the proto. unit insides  :) , (as time permits of course).
Fungus:
My 8060A arrived today!

It seems to work perfectly, it's all in spec as far as my humble volts/ohms/amps references can tell (I'm going to need better references now >:D )

I took it apart to find a date code, etc. I got PCB revision J, date on main chip is week 30, 1989.

As far as I can tell the capacitors aren't Nichicon and look suitably numerous and fiddly to replace. :(  I'm going to leave that job for now.

The self tappers holding the case together were very stiff. Getting the case back together firmly was impossible, the screws were so stiff it felt like I was going to break something. I put a tiny amount of olive oil on the screws and they went in like a dream. Hint: Here in Spain we use olive oil for everything, put some in your toolbox.  ;)
drtaylor:

--- Quote from: Fungus on August 11, 2017, 03:56:12 pm ---I took it apart to find a date code, etc. I got PCB revision J, date on main chip is week 30, 1989.

As far as I can tell the capacitors aren't Nichicon and look suitably numerous and very fiddly to replace.  :(  I'm going to leave that job for now.

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Hi Fungus, Sounds like you got a good one. Rev J was done after I left Fluke. Really makes me want to see the Rev History. As I mentioned earlier, I have mostly PCB Rev H and PCA Rev H. Rev J would be one revision newer as Fluke and most companies skip "I" due to possibility of confusion with "1". If you don't replace the Caps, you could be in for trouble later. I'd use a magnifier and look carefully around the bottoms of all the Alum Caps for any signs of electrolyte leakage (but it may be there anyway and you won't see it). Your caps are >20 years old. But if it works...
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