Just got my "new" multimeter ... the family become larger ..

[Kiriakos-GR]

Currently,  Fluke Europe in Holland , keeps any stock of products.

All ready , I had send one query on a company called as " Sierra IC " .

And did one contact with one local store ,
who has one major Greek contact about Fluke parts at north Greece ,
that possibly could help.


I am doing some thoughts about "  How hard is to convert one LCD circuitry ",
so to operate with LED display ?

Or better said ... Adding one new LED display on a multimeter .




  

 

[david77]

Changing to LED display sounds good, I much prefer LED on bench equipment anyway.

It's also probably a much cheaper alternative .

[alm]

I agree that LED is superior (not sure why they thought LCD was an improvement in the eighties, possibly because it's easier to do alphanumeric and complex symbols). The main disadvantage for this application is power draw, the battery life will probably be worse. But I don't really see the point in batteries for these bench-style meters these days, you can get similar performance in something like a Fluke 87, which is much smaller (but much more expensive).

I believe the interface will be different, especially if they use a direct interface to the LCD (as opposed to a controller like the HD44780). LCD control signals need to be modulated to prevent 'burn-in', and probably has different voltage/current levels. So I doubt that it'd be a drop-in replacement, but it may not be too hard. Didn't they offer similar meters with LED displays? Although these might use a completely different circuit.

[Kiriakos-GR]

Well  thats what it looks like ...  Picture ..

I did try to remove and inspect the display , and now the problem become worst .. the display does not function any more .
The liquid crystal had become totally damaged .

I had just contact and another company for the spare part.
looks to have five in stock. o2xygen.com

This display are originally made by the Japanese OPTREX part code 871126 .
But its not available as part from them .

.

[david77]

Who would have thought to find a Intersil IC in there?
They were the guys who originally brought out the ICL7106/7107 3,5 digit DVM IC's that used to be used in nearly every cheap meter and still are often used in panel meters.

This is obviously a custom numbered IC for Fluke, but could it be.... ?

I did a quick google and came up with this:

Andrew July 4th, 2009 at 02:28

Fluke is not new to off-the-shelf parts and using refence desigsn.

Models from the stone age, like the Fluke 8020, 8022A, 8024 have a main IC called 429100. That one happened to have the same pin configuration as the Intersil ICL7106. The circuits of the meters are very much Intersil reference designs. And not surprising, the 429100 is supplied by Intersil. Guess what IC it really is, just with a magic Fluke custom number …

And guess where I found it? Right here http://www.eevblog.com/2009/06/29/eevblog-15-part-2-of-2-fluke-189-289-multimeter-review/  


If he is right, I don't feel bad about the fact that I'm currently building a special panel meter with 4x 7107's instead of the more modern approach of using some micro .

If it is a 7106 it should be possible to replace it with the 7107, wich drives a LED display.
But it is not a drop-in replacement, you will need to check supply voltage, you will need a +/-5V supply for the 7107. Those IC's prefer their inputs floating with respect to the supply, that can be a bit of a headache.
You would probably have to make your own small board and put the 7107 and some othe stuff on it. But it sounds feasible and quite fun.

[alm]

I would carefully check if the ICL7106 is actually 100% compatible with the Fluke 429100. They may have a common heritage, but it's possible Fluke asked for modifications or selected for tighter specs.

[NiHaoMike]

In at least one design (Fluke 8021B), it isn't. One of the pins has been changed to select scaling factor or something.

[Kiriakos-GR]

I like to thanks you , for the current findings,  all of you  

About the IC , all that I can Imagine as deference from the "regular" version , are the B = Battery indicator.

Other than the " B "  sign addition, its one common design  4 digits  4 scale points and the Minus dash.

About the IC 7107 , It sounds good as idea , but I do not know if it worths as solution , time and money.


Currently I am offering about 30$ , as ultimate price, for finding the Fluke display,
even as used in a good shape.

I will try to find the schematics of both IC's , and see how they looks like.

But I do wonder ,  I am the only one who came at this point ?
All the others what they do with their meters ? they damp them ,trashing them !!

[Kiriakos-GR]

And some more pictures for you all ..    (attachments)

[david77]

Is the 8012A a 2000 count meter or more?  If it is more you can't use 7106/7107 IC's as they're only 2000 count. You said the original LCD has 4 digits and a separate minus dash, so does it count to 10000?

Why not try it another way? You could just go and get a standard 4digit LCD Display and wire that in there. These things are cheap (<5 EUR) and should easily fit instead of the original. The only thing you need to find out which pin on the IC represents which segment. Easy.

I would certainly try and fix this meter, a nice meter is always worth some effort .

David

[NiHaoMike]

Those are some old batteries. 2200mAh C cells. Now 2200mAh and above AA cells are sold in supermarkets, even. (I assume those are for memory backup or an internal clock?)

A few oddball components (current shunts and precision resistors) look very similar to what's in my 8021B. (And despite it being about as old as Britney Spears, it is still very accurate and the frequency response is at least as good as my Mastech MS8226T.)

I think the Flukes using that chipset use a non-multiplexed LCD. It should be easy to build a converter board to allow the original display to be replaced with some LED displays. Red or green for the retro look, or blue for the futuristic look. (Use window tint or something on the display cover to improve contrast.)

[Kiriakos-GR]

The meter is an  2000 counts ..

So it goes at 1.900 V
Or  19.99 V
Or  199.9 V
Or  1000 V

So its three dashes .

By my understanding , The IC and the display , its an common volt meter .

But some how it knows where to set the dash .... in comparison with ready cheap LED panel volt meters,
that you have to set the scale manually with resistors .

My only fear are, that any additional circuitry it will possibly compromise the accuracy of the instrument.

I have to admit , that building converter IC's its not my strong point.    

[david77]

Well, if you replace the display with a off-the-shelf display you wouldn't need any special circuitry. You also wouldn't affect the accuracy of the meter as that is depending on the big Intersil IC.

Unless you get the original part that is probably the easiest solution. Just have to figure out wich pin goes on wich segment, shouldn't be to hard.

David

[Kiriakos-GR]

I will wait for the next 5 days , the responses , of the sellers and companies , that I had ask for help .
At the same time I will start to collect info about the alternative solution.

I all ready have three LED displays (digits)  next to me ..  I am missing the one with the minus sign and the digit.

The manual of the  8012A , has the full schematic in it , I will study it too .

[Kiriakos-GR]

Those are some old batteries. 2200mAh C cells. Now 2200mAh and above AA cells are sold in supermarkets, even. (I assume those are for memory backup or an internal clock?)

Nop,  those are secondary power source , the meter operates with them for few hours .
If I remember correct  .. about 16 hours .