Fluke 1503 to 1507 conversion?

[Tjita1]

Hey guys!
I'm new here, pretty new in the EE-hobby.
Tried searching the forums, but I could not come upon any information on the matter, so here goes.

I happened upon a cheap Fluke 1503 on Ebay, knowing that it's the cheaper version, but pretty sure it would be enough for my needs.
However, when I tore it down, much to my surprise I found all the 1507, the more sofisticated version, buttons hidden under the plastic case, exept of course with lower profile and without writing. It also had the Pass LED on there. I found that a bit interesting.
On further testing (with any bodyparts far away from the output jacks) it turns out that it actually has all the 1507 functions built in to it, includin the 250, 100 and 50V modes, the Compare function, the PI and that other function I cant remember the name of. Pretty cool huh? In other words, all you have to do to turn the 1503 into a 1507 is to change out the case and keypad. Except one thing of course. The 1507 measures up to 10 gigaohms, whilst the 1503 only goes to 2 gigaohms. Now, I can't imagine that it would have all the buttons and LEDs, as well as all the fuctions programmed in the micro, and then not have the 10 gigaohms function on it as well. Question is how to access it.

Any chance anyone here knows about this?
If not, would anyone that has the 1507 in their posession feel the slightest inclination to tear it down and take some high res photos of the board so I can compare mine to the photos, and see if they have maybe changed a resistor or put a jumper somewhere or something of that sort?

The 1503 has some unpopulated pads on the top of the battery side of the board, however I think those are for some type of IR interface rather than for extending the metering range, but I don't know.

[BurningTantalum]

Oh, go on then...

[BurningTantalum]

Actually you have, unwittingly, done me a huge favour- when I removed the battery compartment lid, which I probably would not otherwise have done for yonks yet, I found that two of the cells had started to leak. They were last changed in 2010 at a calibration, I assume, as they are not the originals.

So- the case is still apart so if you need any better pics or closer in to certain areas please let me know.
Regards,  BT

[Tjita1]

Thanks a lot! Unfortunately that didn't really help, mine is completely identical, apart from one single thing; the crystal on mine reads D32.7E9, but on yours it is D32.7M9 as far as I can tell. Is that an actual difference, or is that just a manufacturing date maybe? Mine is date coded 0926, and yours apparently 0948, so it would make sense for the two last letters to represent some sort of period of 2009, and 32.9 being the frequency.

Nope, I'm at a complete loss. I can't see why they would program the functions into the micro only to make a software change in the metering range, but I can't find any hardware differences at all, so that's pretty much what I'm left with.

One last hardware possibility I just came up with, could you take a shot of the flip side of the board, mainly the range switch? It looks a bit off, maybe there's some sort of difference there...

[BurningTantalum]

No problem - here they are. I am not reassembling until tomorrow, and am interested in this, so anything else- just holler.
Just to clarify- the 'extra' buttons operate, and the relevant functions display correctly and function correctly? I take it that it shows 'over range' if a resistance over 2G ohms is measured?
Regards,  BT

[Tjita1]

Nope, I can't find a single thing that is different. It must be encoded in the software somehow, but again, why would they do that and not remove any of the other functions? Every button (hidden under the cover) and the extra voltage modes work just fine, it's just that it's limited to 2 gigohms (it reads >2200 Mohm on the display when you're above that).

Not that it matters though, here in Sweden the standard is 1 megohm per volt, so 1000 megohms at 1000 volts is what you want here, but it would be nice to have the functionality.

Thanks for your help however. Maybe I'll get back to this thread if I find something out later.