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sako243
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No clue I'm afraid. From what Ben said the 655D is completely different to the 655C. I did reverse engineer some of the pins so I can dig out those notes if I can find them.
Would it be so noticeable, especially if you didn't mention it, if the pivot point was shifted up a bit - the angle of the needle would change a little, but it would still point in the right areas.
As has been suggested, a slot in the case to allow the motor casing to poke through as you fan-dangle it in place.
I would imagine it won't be the smoothest idling, running thing, or the most softly suspended, so avoiding engineering in any extra failure points in linkages, pivots, gears, would be my plan.
I do like the idea of seeing if the internals of some other gauge could be made to work - an old Smiths unit maybe - would probably need something to adjust/convert whatever signal is from the sender unit, but I'm sure that would be childs-play to a man who knows what he is doing.
As has been suggested, a slot in the case to allow the motor casing to poke through as you fan-dangle it in place.
I would imagine it won't be the smoothest idling, running thing, or the most softly suspended, so avoiding engineering in any extra failure points in linkages, pivots, gears, would be my plan.
I do like the idea of seeing if the internals of some other gauge could be made to work - an old Smiths unit maybe - would probably need something to adjust/convert whatever signal is from the sender unit, but I'm sure that would be childs-play to a man who knows what he is doing.
A rear view of one of these might be useful . .
NOS Leyland Parts temperature gauge Austin Metro MK1 / Allegro 3 | eBay UK
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Ah, Veglia Instruments...A rear view of one of these might be useful . .
NOS Leyland Parts temperature gauge Austin Metro MK1 / Allegro 3 | eBay UK
Find many great new & used options and get the best deals for NOS Leyland Parts temperature gauge Austin Metro MK1 / Allegro 3 at the best online prices at eBay UK! Free delivery for many products!www.ebay.co.uk
.... or as they were known iirc on Italian Motorcycles : "Vaguelier"
sako243
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That why (I think) I said, sort of like, didn't know what else to call it.
If it's rewindable that'd be great (e.g. by @m_c's friend) - not something I want to do but I'm happy to palm it off.
There's 140Ω across the outer two teminals and open circuit to the centre pin from both outer ones. The coolant gauge measures 140Ω across the outer two and ~530Ω between right two.
I need to double check on the machine as now I'm sat down thinking about it it doesn't make sense.
Looking at the front of the gauge the right-most pin definitely had 12V on it and this makes sense. The left most pin appeared to be ground but I'm fairly sure it's the centre tap of the two coils thus the connection for the sender and the middle offset pin should be ground.
sako243
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Oh I know it could be re-wound - just not something I want to do!
I'm fairly sure, and rather annoyingly, it's the red winding that's gone so that means taking off the gold one as well.
Wonder why the enamel is different colours.
sako243
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It does look like the windings are configured in the same way as the diagram I posted above (random one found on the internet).
If you make the assumption that the sender goes open circuit at one extreme and short circuit at the other (for the sake of explanation) then in the short circuit case the "full" coil in the diagram is eliminated as both sides are now grounded so the high side coil (empty / left on the diagram) is the only with any current flowing through it so pulls (one assumes) the needle towards it. In the other situation where the tank is full and the sender goes open circuit then that whole path is eliminated from the diagram and both coils get power flowing through them but things must be biased in such a way that the needle points at full.
If I remember correctly this sender is ~10 to 160Ohms but the coils / butterfly attached to the needle must be balanced in such a way that the equivalent resistances of the coil and the coil with sender in parallel offset the needle the correct amount. Basically I'm not surprised they're not the same reading but without going through all the geometry and magnetic flux equations I'm not sure I'll be able to work out what they should be.
There's a very slight mechanical biasing when the gauge is vertical because of the butterfly plate at the pivot point on the needle (the gauge is mounted vertically).
If I apply 12V across the outer two terminals (which I'm fairly sure are 12V on the right as looking at the gauge and the mid-point where the sender should be attached) then it goes full. If you kill the power then it drops back down to empty.
They appear to be - I have reflowed, cleaned up and reflowed them again. It really looks like a winding has broken somewhere inside the winding which ties in a little with what Ben witnessed in the digger. The gauge was working fine and he had about half a tank (ironically whilst doing some tidying up at ours before our wedding) and then the next time he glanced down at it it said full which didn't make sense since fuel doesn't usually magically appear.
Since then it's been a bit intermittent. I tested the sender (and he bought a new one) and found no issues with them and the wiring to the cab seemed fine and at the time the gauge was behaving itself properly. Then an "automotive" wiring guy came out and also had a quick look whilst he was working on something else and got the gauge to misbehave properly. It definitely looks like a break in the wire that was intermittent to begin with and has finally given up the ghost.
My suspicion is perhaps they are different grades of wire and thus allow for different coil resistances
Seadog
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Good point. I'd forgotten the config. diagram
