Unwell Fluke 1652

[JohnW2]

The lead sockets don't look as though you can do much to them.

One doesn't need to - they are remarkably simple. The contact is just 'split' (see the 'naked' PE one below), protrusions inside the coloured sheaths preventing the two halves touching - so, as you say, anything metal inserted will connect the two halves (which have separate connections to the board). Mine are also spotlessly clean - no suggestion of any tarnishing etc. Just to be sure, I've tried explicitly connecting the two sides (of the L and PE ones) but it still thinks that there are no leads. As expected/feared, I therefore think the electronics has gone awry and is not properly recognising that the leads are plugged in ....

Kind Regard, John

 

[EFLImpudence]

Ah, that's a pity.

It seems a trifling fault to render the machine unusable.

 

[JohnW2]

Ah, that's a pity. It seems a trifling fault to render the machine unusable.

Very much so - and BAS seems to have a point that it is failure of an 'unnecessary' function that has seemingly rendered the machine unusable.

It looks as if it might well work if only it could be made to realise that leads were plugged in (or if one could over-ride that 'function'!) - the display is looking normal and changes appropriately when one switches to different functions, so the main processor must be more-or-less working.

I'll have another look/play, but I think I'll soon have to give up!

Thanks for your interest.

Kind Regards, John

 

[endecotp]

I guess it has some relays, right? Investigate them.

 

[JohnW2]

I guess it has some relays, right? Investigate them.

Thanks for your interest. Yes, it appears to have 6 relays - although, without a circuit diagram, I obviously don't know what any of them do. In what way/sense would you suggest that I investigate them?

Kind Regards, John

 

[Lectrician]

We had one do this. £110 fix, returned to Fluke.

 

[bernardgreen]

What could a Fluke 1652 do if no test leads were inserted that would be so hazardous to people

A check for dead ( no voltage ) would give a false "safe" result ( no voltage found ) if the lead had been pulled out of the socket and the user had not noticed the lead was out of the socket.

 

[ban-all-sheds]

True, but wouldn't one have used the instrument immediately beforehand to check that it correctly registered a known good voltage, and then again immediately after to check that it hadn't failed during testing?

 

[endecotp]

Thanks for your interest. Yes, it appears to have 6 relays - although, without a circuit diagram, I obviously don't know what any of them do. In what way/sense would you suggest that I investigate them?

My thinking is that this "multi-function" tester probably multiplexes its probes between the multiple functions using the relays.
If it is stuck on the wrong function it may not be able to use the lead-present feature.
You might be able to tell if this is correct by following PCB tracks.

I would check that all the NC contacts are closed and all the NO contacts are open, and that nothing rattles.
I'd then consider applying a voltage to the coil and seeing if that makes it change over - but there is some danger of damage from doing that.

 

[JohnW2]

We had one do this. £110 fix, returned to Fluke.

Thanks. At that price, it might be worth considering, since I'm unlikely to get a replacement for that figure (used 1652s seem to be going for £180-£200 on eBay).

However, there are a good few places out there offering (often 'fixed price') repairs of these machines, and a couple I've seen are quoting 'fixed prices' of around £180, coupled with boasts that this is a lot less than Fluke would charge. I therefore wonder how long ago you got the problem fixed by Fluke for £110?

Kind Regards, John

 

[JohnW2]

My thinking is that this "multi-function" tester probably multiplexes its probes between the multiple functions using the relays. If it is stuck on the wrong function it may not be able to use the lead-present feature. You might be able to tell if this is correct by following PCB tracks.

That all makes sense, albeit there are three different types of relay, physically scattered all over the main board and (FWIW) only one or two are physically close to the lead sockets.

I would check that all the NC contacts are closed and all the NO contacts are open, and that nothing rattles. I'd then consider applying a voltage to the coil and seeing if that makes it change over - but there is some danger of damage from doing that.

If my guesses about connections are correct, it seems that, without power, each of the relays has one pair of closed contacts and the other assumed contacts open. Nothing obviously rattles! On powering up (as far as it will go) voltage does not seem to appear across any of the (assumed) relay coils - but that may simply be because failure of the 'lead-present test' prevents very much happening at all.

Kind Regards, John

 

[stillp]

I therefore wonder how long ago you got the problem fixed by Fluke for £110?

Why not 'phone Fluke and ask for an estimate?

 

[JohnW2]

Why not 'phone Fluke and ask for an estimate?

I probably will, but if £180 really is "a lot less than Fluke would charge", I won't be holding out much hope of getting an 'acceptable' answer! Realistically, even if it's not "a lot less", one imagines that it's probably at least a bit less - since otherwise I doubt that these 'third party repairers' would get much business!

Kind Regards, John

 

[stillp]

Given your description of the sockets, can you see what is in series with them, which might give a clue as to how the presence of a lead is detected? For example, a relay coil might be in series with the split contacts, thus energising the relay when the contacts were joined by a lead plugged in.

 

[JohnW2]

Given your description of the sockets, can you see what is in series with them, which might give a clue as to how the presence of a lead is detected? For example, a relay coil might be in series with the split contacts, thus energising the relay when the contacts were joined by a lead plugged in.

I've been trying very hard to trace the circuitry, but it's far from easy.

One side of the ('split') L lead socket, goes through the coil of a little toroidal transformer and thence through a fuse (** see below). If one removes that fuse, on power-up one gets an "Err1" message ("failed self-test - return to manufacturer"), rather than the "LEAd" message.

** that fuse seems a little 'naughty'. Unlike the one which is easily accessible (and replaceable) within the battery compartment (which I suspect is also effectively in series with the L lead), one cannot even see, let alone replace, this second one unless one completely dismantles the machine. ... it would appear that if that second fuse blows, most people would end up having to return the machine to Fluke for 'repair' (at whatever cost!).

My attempts to trace the circuitry continue ... "A circuit diagram, a circuit diagram, my Kingdom for a circuit diagram"

Kind Regards, John