Electronics > Repair

Is a Fluke 8000A worth repairing?

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Alex Eisenhut:
That's a '70s-vintage DMM I picked up while thrifting, it had 4 D NiCads in it which I recycled. There's a bit of leakage damage and a bit of "green meanies" on the PCB, but nothing huge.
But looking at it, I'm kinda surprised at the cheapness of the thing, I thought Fluke was supposed to be premium stuff or did they really improve in the '80s?
The way it's built it
1) Needs a special AC cord
2) Needs the batteries to work.
3) Uses an incandescent bulb as a current regulator for charging the cells. Clever for the 1930s, but even in the '70s surely there was better?
There is a Northern Telecom sticker on the thing so it must have been considered good at the time?

Is it worth putting in time and effort for what seems like a very basic DMM? Or should I keep it as a display gizmo?

From what i've seen, Fluke are past masters at getting performance out of deceptively simple circuitry. The essence of good engineering. Any fool can throw $ at a problem, but takes a good engineer to get the best out of little. Sure, it's worth fixing, respect, even if only kept as a backup...

those switches on it are super annoying

Fixing one is certainly a bizarre side trip into some interesting engineering choices.  There's a surprising number of variants of this meter and some came with a few unique options like data output, battery, and  impulse (amp-seconds) for specific purposes.  I think it was less expensive than other digital meters of the era.

I'd bypass the power supply section and power it up to see if it works or not.  If not, these use a rather strange system of converting volts to counts--they have some hybrid ICs with matching resistors and capacitors that were (and still are on eBay) sold as a set.  The meter essentially couldn't be calibrated if these parts weren't matched.  The design was one chip as a 'precision' VCO and another as a gated counter, then some logic for the displays.  So volts-to-frequency, count the frequency and display it.  If those chips are toast--and they often are--there's no fixing it without them.

it's a 3.5 digit bench multimeter with .1% annual accuracy specifications. it has less resolution and worse accuracy than modern high-end handheld multimeters. i've never considered buying one for repair or anything else. maybe you could use it to learn more about multimeters.

8800A's are quite nice, especially the later generation.


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