A triplet of 23s, Fluke 23’s that is

[Robomeds]

A triplet of 23s, Fluke 23’s that is
So I happen to have 3 very similar meters with me at the moment so I thought I would pull them apart and compare.  Techincally I don’t have 3 23’s.  I have a 23, a 73-III which I think is the gray version of the 23-II and a 23-III. 
The teardown of the three is quite interesting.  The 23-I is to the best of my knowledge the original version of the little boxy meter that was the 2x and 7x series.  This 23 appears to have been made around 1992.  The style of circuit board is similar to what I’ve seen in old Fluke 87s.  The routing and edges feel crude compared to the later Fluke stuff.  Still, the layout is remarkably clean and tidy. 
The 23-III is only 7 years newer yet two generations removed.  Again the layout is very clean with what appear to be only a few components.  At least we are seeing a real collection of surface mount devices.  We also see a Fluke IC that looks familiar to the older meters.  All three of these have the 683052 IC running the show. 
The 73-III of course isn’t quite a 23 but close enough.  This one was purchased new around 2002.  That means the replacement series (the 23-3 and 7x siblings) were already on the market yet Fluke sold this older model.  Perhaps just as well.  In a number of ways this is the best of the bunch.  All three have basically the same specs and features but the small differences mater.  Touch Hold, one of my favorite Fluke features, can’t be easily accessed with the old 23.  You have to turn the meter on while holding the single button.  Not at all a convenient way to access the feature.  Also the bar graph doesn’t update when the display is held.  On the newer meters this isn’t an issue.  So even though I like the yellow it would be the first to go. 
The 23-III works nicely and having an actual hold button is better than the 2 second press and hold.  However, the yellow over mold just doesn’t protect like the cases of the older meters.  It’s harder to clean too. 
Still, note all the shielding inside of the 23-3.  That’s a lot of plastic that people will normally never see. 
The 73-III vs 23 is interesting because the two box meters are almost the same on the inside.  The newer meter’s circuit board is cleaner and they added some new routing and plastic walls since the first meter. 
With all three of these apart I started thinking about just how simple Flukes look on the inside.  It’s like they were designed by mechanical engineers.  There are lots of plastic shields and walls but seemingly few components.  If you take apart a meter from one of the other companies it seems full of various electrical bits.  Fluke makes it look like there meters have nothing but protection parts and plus the screen and an IC.  It makes them almost distinctive on the inside vs other meters.  Quite nice even in Fluke’s cheap meters*

Saying cheap Fluke meter is like saying cheap Apple product.  Even the low end Apple products are nice because well, low end Apple pricing is still pretty high end!

[retiredcaps]

I forgot to respond to this post with all the "noise contest" posts here lately.

Anyway, thanks for showing the generations side by side.  As for the touch hold on the original series and series II, I have found that you can turn on the meter first, and then quickly press and hold the middle button for 2 seconds to enable auto hold.

Personally I like the III over the II mainly due to the larger digits and better range switch feel.  I do wish the III had integrated probe holders like the series II rubber holster.

PS. Congratulations on your latest Flute.  That one didn't show up on my radar due to the spelling mistake.

[Robomeds]

Thanks.
I know what you mean about the larger display with the 23-3 and a dedicated hold and range button vs the combo button.  The very good LCDs on these meters really makes me wonder why the more recent Fluke 87V and 11x series have rather low contrast screens. 

Something I don't like about the 23-3 and similar meters is the rubber overmold instead of a boot.  I think that was Fluke's cost reduction plan at the time since the 189 and similar meters used the same idea.  Happily Fluke seems to have moved back to boots. 

Anyway, I'm looking forward to my new Flute. 

[ModemHead]

I think the 23 and 77 models were always paired as far as the yellow/gray thing goes.  So were the 21 and 75 model numbers.  The 73 was like a 77 except without the mA input jack.  When the "III" generation came along, they dropped the yellow/gray distinction.  The 2x-III models were exactly the same but were sold with premium silicone leads and maybe some other bits.

The 73-III seems to be an odd child introduced along with the new "tapered style" 77-III, perhaps just to have an updated meter that still had the old rectangular form factor.  I'm not sure, I wasn't paying attention at the time.

Regarding the simplicity of the older meters, I think Fluke's custom silicon and basic feature set allowed them integrate just about everything into the ASICs except the front end components.  It made for a highly reliable tool.

BTW, careful with your old yellow Flukes.  I have found the yellow plastic to more brittle than the gray, leading to problems with the internal screw posts for the self-tapping screws.

[Robomeds]

The 77-3 in the pictures was a trade school branded meter.  Perhaps Fluke thought the later tapered housings wouldn't hold up as well as the older square models.  I would believe that given that in our labs we have a few 17x's where the overmold is pealing off.  I'm not a huge fan of overmolds.  They do add some grippiness but not much in the way of durability.  They also are a pain to clean if you care. 

MH, I think you mentioned the yellow plastic bit on your blog and I was careful.  I've always be careful about this sort of thing.  I'm not a fan of plastic screws for areas where disassembly is common.  Cross threading is far to easy.  That said, Fluke's screws are better than most thanks to the relatively large lands between the teeth.  Also with a 2000 hour battery life you shouldn't be changing batteries often in any of those meters. 

I can buy the ASIC explanation.  Really, even the 89-IV meter on your blog looks simple inside compared to a number of lesser meters.