Duo14 is failing

alastairgott

Well-known member
Not very good with electrics but my duo is currently on the blink. it seems to be a problem separate from the 14 led or halogen side. but I cannot be sure.


It seemed to be fine on the halogen side with my bisun upgrade but that was also failing so it must be further into the light.


anyone got any ideas of where I can poke a multimeter (other than up my ...) and what I should be looking for?
 

Alex

Well-known member
I had that issue, took it into Inglesport, said it was just the battery contacts, cleaned them and it worked a treat, until I sold it for a far brighter light.
 

potholer

New member
Its it flickering randomly, or apparently in response to motion/shaking/knocking?

Cable is probably the easiest to investigate - with the light running and without moving anything else, does gentle manipulation of the cable, particularly near the ends, tend to make the issue come and go, or make no obvious difference?

What about squeezing/tapping the battery box? As well as checking for corrosion on contacts inside, are any spring contacts in the removable holder seeming more compressed than the others?

As far as multimeters go, inside the headset, the plate that touches the bulb is permanently connected to battery +ve, the bulb rim (the segmented ring contact at the base of the thread) to battery -ve when the switch is up, the lower pin on the 14LED permanently to battery -ve, and the upper pin to +ve when the switch is down. I can't recall if the tops of the pins are accessible with a probe when the 14LED unit is in place.
 

Joe90

Member
I know somebody who had a similar problem, turned out to be where the wire goes into the back of the lamp housing. Try wiggling that a bit.
 

alastairgott

Well-known member
Potholer, it's mostly flickering randomly, so I'll try your suggestions. As well as everything else on this page. As it also sort of responded to bashing.

Thanks!
 

Mike Hopley

New member
+1 to Potholer's suggestion.

Inside the battery box, the contacts are flexible metal strips. Over the years these get weakened and become less springy, so they no longer press against the battery.

I recently fixed the problem on my old Duo, just by prising the contact strips out again, so that they contact the battery better. Not sure how long it will last.
 

Peter Burgess

New member
I would also check both ends of the batteries as well. My Duo 14 was starting to do much the same thing but a quick clean of the ends of the batteries which had developed some degree of a black coating, has helped no end.
 

crickleymal

New member
If the spring contacts for the batteries are failing sometimes you can pack them out with strips cut out of a soft eraser or something similar. It gives them some more spring without having to bend them (which eventually will straighten out again).

Failing that take it apart and look at all the joints in the wires and take a soldering iron to them.
 

ghost

New member
If you're determined to use a Duo, so be it - good when brand new, but very soon become a source of despair. There are other much more reliable, non-flickering, lights for the same money or less. Those funky Chinese lights appear to have their own new shop (although not quite open for business just yet):

http://www.subg.org.uk/lamp_shop/lampshop.htm

;)
 

Peter Burgess

New member
I have used a Duo-14 regularly for - err - not sure, but 6 years I think. All the LEDs still work, nothing has gone wrong yet, as a middle of the range reliable lamp, I can't fault it. Any flickering I have had was due to build up of gunge on the ends of the batteries which can be cleaned off in seconds.
Of course, there will always be those keen to see me replace it with something else, especially if it brings them some business. I tend to take more notice of those promoting lamps if they can show their good qualities instead of knocking the opposition!
 

cavermark

New member
Peter Burgess said:
I have used a Duo-14 regularly for - err - not sure, but 6 years I think. All the LEDs still work, nothing has gone wrong yet, as a middle of the range reliable lamp, I can't fault it. Any flickering I have had was due to build up of gunge on the ends of the batteries which can be cleaned off in seconds.
Of course, there will always be those keen to see me replace it with something else, especially if it brings them some business. I tend to take more notice of those promoting lamps if they can show their good qualities instead of knocking the opposition!

SUrely "non-flickering" is describing a good quality?
 

potholer

New member
And a quality which seems to apply to most Duos.

The line between describing positive points and criticising alternatives by implication can be a bit blurry at times, and much can come down to presentation, as well as how explicit and specific one is.

There'd be a difference between describing a light as 'having a nice long tail-off as the battery fades' (and/or having power management to give advance warning of depleting battery) and saying that 'it wouldn't just cut out and leave you stranded in the dark' - the latter kind of description of a positive point as a non-negative one tends to point a finger of criticism elsewhere.
 

Peter Burgess

New member
ghost said:
If you're determined to use a Duo, so be it ....
... very soon become a source of despair.
There was no determined attitude in my case. I saw others using them, asked what they were like, and made up my mind based on reason and budgetary considerations.

No, mine did not become a "source of despair". Not very soon, nor after several years. Those I know who have replaced them did so because they could afford a top of the range lamp. Others have kept them and upgraded, which I don't think they would have done had their lamps been a source of despair.
 

Les W

Active member
If Duos were no use then CustomDuo wouldn't be making and selling lots of upgrade modules for them...
(y)
 

ghost

New member
Peter Burgess said:
ghost said:
If you're determined to use a Duo, so be it ....
... very soon become a source of despair.
There was no determined attitude in my case. I saw others using them, asked what they were like, and made up my mind based on reason and budgetary considerations.

No, mine did not become a "source of despair". Not very soon, nor after several years. Those I know who have replaced them did so because they could afford a top of the range lamp. Others have kept them and upgraded, which I don't think they would have done had their lamps been a source of despair.

Here are quotes from a few unhappy Duo users on this very forum. Their words, not mine:

===================================

First the recent problem with the yellow battery case. Four AA batteries are mounted in a black carriage with a yellow top. The carriage is clipped into the yellow case by two metal clips which create a water tight seal with a d-ring. The yellow top to the carriage has cracked and broken completely. This is a result of the pressure applied by the two metal clips. Previously I had been surprised by the force applied by these clips when putting the batteries in the case. When I mentioned the problem to Tim on a recent trip to Shatter pot he discovered that his nearly new duo also had a crack (so new it may be within warranty).

=======================================

The second problem with the duo which I have lived with almost as long as I have had the light is that it is nearly impossible to open
even when brand new and certainly not after a few caving trips have got dirt into it
. We have tried hot water soaking etc..
brand new duos (almost everyone in our tiny club has duos). This became an issue when someone wanted to replace the halogen bulb with an led
and we failed to open it. It became a more important issue when my halogen bulb failed. However since I almost never used the
halogen light except accidentally this was not an issue either. However it is another example of a design flaw in the
petzl duo lighting system
.

=======================================

I recently noticed that mine wasn't as bright as i remembered and probing around with the mutimeter showed high resistance (100ohms  ) between the battery terminals and the bulb contacts, so stripped it down and replaced the wiring. the knife edge contacts to the cable are a point of failure with the duo. soldering the wires on improves things but soldering to stainless steel is tricky to do as the solder doesn't take too well.

========================================

I found when I took mine apart, the ends of the wire had corroded and gone green. Replacing the wire was easy enough but now, despite silicon sealant, the whole unit lets in water. Not disatrously but enough to have little beads of damp between the LEDs and the lens.

So be careful - these things don't like being taken apart, and as you can see from Christian's pics they are a bit "mickey mouse" inside - especially the switching system.

=========================================

Judging by the amount of people on and off this forum with similar stories its safe to say that they are not waterproof and only last about a year (of average use, and average maintenance**) before the wires corrode, resistance goes up and brightness goes down...
** there will be exceptions to this rule

========================================

One funny thing I noticed - for the one-off mod I was thinking of for a friend, I was trying to work out possibilities for a switch - the regular switch lever seems only to be held into the headset by the switch contacts, so I was thinking of maybe ignoring that and doing something using the focussing lever as a more solid control.
In my headset, that lever was stiff, so a month or so ago, I tried a little silicon grease on it and that made it much worse.
Just playing around with it now, it has greatly freed up, and is much freer than it was before the grease was applied, despite me doing nothing but leave it alone.

===========================================

I guess the wires had gone green due to moisture, I noticed a lack of brightness after a year or so then decided to operate on it.

Yes, it was bathroom silicon - around the wire entry point as there should be no movement there.

The O rings which "seal" the switch and zoom control are also poxy, in fact the more I write the less I like about it.......

============================================

So has anybody come up with a way of properly sealing a duo yet? I'm having to keep on opening mine up to dry it out and it flickers like crazy.

===========================================

Have a look in the bottom of the battery box if its flickering the last one i repaired had corrosion between the flexy cable and the stainless battery contact

==========================================


None of these faults are acceptable for a caving lamp, which is after all an activity which has a tendency to place you in life or death situations. The Duo has lowered people's expectations about what constitutes a reliable lamp.

Roy Fellows, one of the UK's most respected lamp builders, concluded: "By the look of it the Duo is not fit for purpose, end of."
 
So that's eight or so negative comments and from that tiny fraction of Duo users from around the world you deduce ......
Judging by the amount of people on and off this forum with similar stories its safe to say that they are not waterproof and only last about a year (of average use, and average maintenance**) before the wires corrode, resistance goes up and brightness goes down...** there will be exceptions to this rule
I would suggest that, based on those figures, the number of Duo's sold and the number of upgrades sold by Biff and others that the faulty ones are the exception to the rule.
I've found the Duo's I own excellent in terms of reliability, durability and maintainability.
 

potholer

New member
I've opened a fair few Duos and they all seemed to be dry.

Having had cause to open quite a few to stick various inserts inside, I think there was one which neither the owner or I could open when we wanted to (I was being a bit wary since I didn't want to break it off his helmet, but he did get it open eventually at a later point).

Now personally, I'm a fan of Oldham headsets  (I like something I have a decent chance of repairing on a mountain or underground with a Swiss Army knife), but i'd be remiss if I didn't admit coming across Oldhams which leaked, and some which were a real dog to get open, and which would have been unopenable without either a vice or [ideally someone else's] door frame to grip the back of the body.
For both Duo and Oldham, I suspect there may be similar causes some of the time, like a combination of greased threads and enthusiasm on closing ,where at most one of those should be present.

Sure, when Duos fail they aren't exactly made for fixing, but a list of problems out of the context of their abundance is pushing things a bit.
And in the relatively unlikely event of a serious problem, if someone has invested meaningful money in a decent upgrade from Biff (or from me), they can currently replace the host with a used one for a reasonable price.

If someone selling an imported niche car was trying to make a point out of how many more people in absolute terms were reporting problems with Astras or Focuses, I'm not sure how many people they'd be likely to convince compared to how many they'd be likely to put off.
 

Peter Burgess

New member
My first lamps was an Oldham. I don't remember how many times I had that lamp apart, fiddling with terminals, fuses, contacts, cables. It was forever having to be sorted out. On one occasion, I opened the boot of my car to find a pungent burning smell, and a nasty black mess under the cap of the cell. Fortunately, it hadn't set fire to my car. Was that lamp "fit for purpose"? Well, it was quite old by that time, but my Duo has been almost trouble free in all the years I have had it.

My other observation is that I have noticed my attention being drawn to a particular website which sells Chinese lamps, by links in posts from a particular user on AditNow, and now here by Ghost. I can't help wondering whether this is more than a coincidence. Not that there is anything wrong with promoting a business - good luck with it. Anyone wanting to sell lamps that aren't Duos is going to be keen to point out reported faults in the competition. But rather than do this, why not ask cavers here and elsewhere to tell us about their experiences of these lamps from China so we can make a fair comparison?
 

ghost

New member
Peter Burgess said:
My other observation is that I have noticed my attention being drawn to a particular website which sells Chinese lamps, by links in posts from a particular user on AditNow, and now here by Ghost. I can't help wondering whether this is more than a coincidence.

Peter - I do wish we could talk to each other without kicking each other in the balls. But when two huge egos (both with decades of experience and groundbreaking discoveries under their respective belts) are in the same room, that's sometimes what happens. Sigh  :halo:
 
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