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750 vs 906 vs 907 dash

Posted: Tue Apr 04, 2023 11:26 pm
by nickta
Hi.
Over the last few years I have come into the possession of a 906 and a P750 to share the shed with the 907. I have finally got around I starting them up and getting them all serviced and all the other good things to make them work.
The 750 is now in numerous pieces, but is a runner. The one thing that is driving me nuts is the oil temp gauge doesn’t register. The sensor tests out ok (about 2kohm at ambient temp) and I have a spare just in case. The wiring buzzes out all the way through which leaves the gauge itself. So the $90 question. Is a gauge from the water cooled version the same as the oil cooled version? Ignoring the black plate that screws to the front. I have a dash from the 906 that is past use by, but I have a replacement, so it would be a matter of removing the temp gauge, change the plate and screw it in. Without a working oil gauge I can’t test the coil resistance of the oil gauge to compare. I do have a water temp sensor which I haven’t tested yet, so that is next. Any thoughts?
Cheers
Nick

Re: 750 vs 906 vs 907 dash

Posted: Wed Apr 05, 2023 3:23 pm
by Mc tool
Hi Nick ,I bought a p750 dash as a spare and then realised that the 750 was oil cooled , soooo yeah I sure they are the same 😁🙄.
I figure that the measured temps , be they oil or coolant are going to be pretty much the same , oil may be 10⁰c hotter during normal use . I cant see Ducati making a whole new set of sensor/ gauge and I suspect that the only difference is the plate you refer to .
I thought that if there was significant difference in readings one could "trim " the sensor by adding resistance either in series or parallel . I did a bit of this mind bending ( I hate maths 😁)stuff balancing load cells on weighbridges (at Tiwai aluminium smelter ) ...........or you could just bend the gauge needle so it was mid range at normal temp and sorta not worry about the numbers to much 😉 .

Re: 750 vs 906 vs 907 dash

Posted: Thu Apr 06, 2023 12:17 am
by nickta
Hey Hamish.
Everything looks the same, even down to the membrane PCB. It looks like the previous owner may have even replaced the gauge at some point as it is a bit different in its mounting, so this issue may have been there a while? I just went for it and put in the water temp gauge in to see if anything happened. It didn't! Still sits at the low point no matter how warm the oil gets. I did check the resistance of the water and oil sensors I have. The oil starts at about 2200ohm, and drops to about 700 when at operating temp. The water sensor starts at around 2600ohm and drops when warmed up (no low point). So I'm back to what powers it up. There maybe a small fracture in the copper tracks, or it could be a dud earth. Never seen one of those on a Ducati!? The bike hasn't had the ignition switch mod, so there is a bit of a drop in volts across the switch (about 2.5volts), so this may also be causing an issue. It's nice and warm in the shed at the moment, so it's not a challenge to sit there and play Auto Electrician for a couple of hours.
If all else fails, I will put in the old 906 dash complete with the oil temp gauge and see what happens? What could possibly go wrong?
Cheers.
Nick.