Lead-free solder is such a PITA (rant/whinge) - Page 2

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Re: Lead-free solder is such a PITA (rant/whinge)



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You seem to have the fault identified, but just to add another
perspective - since you're getting multiple failures of the solenoid
coils, and you're /assuming/ RoHS lead-free soldering is to blame
without having (yet) found evidence, perhaps you could look at other
common factors.  Is the supply voltage to the coils stable, for
instance?  Loose connection causing unstable voltage/surges/sags at the
coil?  Voltage too high? etc. etc.

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Re: Lead-free solder is such a PITA (rant/whinge)
wrote:

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Fair comment.


Without logging it (and I don't have access to a Dranetz any more) I
would venture that it is.  Reading taken at random times show good
regulation, and nothing else in the place which is surge-prone
(electronics and incandescents) is dying at all.

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Nope, snug as.

Re: Lead-free solder is such a PITA (rant/whinge)
On 07/09/2016 21:48, pedro wrote:
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Can you buy the same coil type but in a 24 Volts AC version? If so, that  
plus a transformer may be more reliable than the 240VAC version.


Re: Lead-free solder is such a PITA (rant/whinge)
On Thu, 8 Sep 2016 18:01:33 +1000, Chris Jones

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Well the winding wire will be heavier gauge at 24VAC.  Whether that
will achieve a more reliable ROHS solder bond is unsure, but it
probably couldn't be any worse.

Re: Lead-free solder is such a PITA (rant/whinge)
On 08/09/2016 19:17, pedro wrote:
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It is possible that the solder has dissolved too much of the fine wire,  
making it too thin. I have had a lot of trouble soldering very fine  
wire, especially with lead-free solder - the wire will get thinner as it  
dissolves in the molten solder, leaving it even less robust than its  
original fragile state. Leaded solder that was deliberately  
pre-saturated with copper ("Savbit") was supposed to be good for  
preventing that, but I found it generally unpleasant to use.

As your coils develop their faults over time, I also wonder if the  
manufaturer left some fairly active flux inside the encapsulation that  
might be slowly eating the wire near the solder joint when it is warm.

Perhaps you can tell whether the break is at the solder joint, by  
measuring the low-frequency capacitance of each terminal of the damaged  
coil with respect to everything else. I doubt that knowing where the  
break happens would be much use to you, but it is something the  
manufacturer should be looking into.





Re: Lead-free solder is such a PITA (rant/whinge)
On Fri, 9 Sep 2016 00:48:54 +1000, Chris Jones

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Really don't know.  The Pentair/Tyco/Goyen engineer that I discussed
this with asked for a failed one to be returned for evaluation - so I
sent two (as I have a pile of them otherwise just gathering dust).
When I followed up a few weeks later, he had departed and his
replacement was unaware of the whole matter, and could find no record
of their return despite supplying him the RMA number.

He also declined my offer to send more, really being disinterested in
finding out the reason for the failure.

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The failure mode is going open cct when hot.  As they cool continuity
returns.

I have made up a test lead with pea lamps that I connect up so there
is a (6V) lamp in series with each coil.  When there is a failure I
connect this into circuit and re-energise the oven.  (Doesn't take
long, I'm getting pretty polished at that now!)  It typically takes
about ten minutes to get back up to failure temp.  Then I can see
which coil is going O/C and replace it from my stock of new spares.

To be able to test it would require a fair bit of setting up.

See above re manufacturer "interest".  They sell quite a number of
these during our winters as they are used in gas wall furnaces.  I
guess they are figuring that as long as they keep selling them as
replacements, why investigate.

Re: Lead-free solder is such a PITA (rant/whinge)

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Can the valves be relocated to a cooler location? Or can you
substitute more robust valves made for hot location use?
Eric

Re: Lead-free solder is such a PITA (rant/whinge)
On Thu, 08 Sep 2016 08:12:34 -0700, snipped-for-privacy@whidbey.com wrote:

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See reply to JL for what would be involved.

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The Pentair people (valve manufacturer) said they have no such
solution.

Re: Lead-free solder is such a PITA (rant/whinge)
says...
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Have you looked into another valve company ?

I retired a few years ago from a large company and we had hundreds of  
valves similar to that and very few of them failed, especially the  
coils.  Most  did operate on 120 volts.

Not sure how the valves are in your oven, but maybe you could try 2 of  
the 120 volt coils in series.


Re: Lead-free solder is such a PITA (rant/whinge)
On Fri, 9 Sep 2016 10:03:15 -0400, Ralph Mowery

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No


Of course at 120V the wire would be twice the diameter.  If it is
corrosive flux at work, it would take longer to eat it away.  If it is
failing Pbfree solder bonds, who knows.

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I am considering that.  Meanwhile SWMBO is considering a replacement
oven (which as you'd all know, means a complete new kitchen)

Re: Lead-free solder is such a PITA (rant/whinge)

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I meant outside of the oven enclosure. Bypass the valves with plumbing
in the enclosure and then put the valves somwhere else in the gas
supply line.
Eric

Re: Lead-free solder is such a PITA (rant/whinge)
On Sat, 10 Sep 2016 10:05:58 -0700, snipped-for-privacy@whidbey.com wrote:

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Yes that is a possibilty, but in our over-regulated environment it'd
require all sorts of recertification, almost like the
aviation/aerospace industries. Having been exposed to THAT industry
it's a path I don't want to tread out of MY wallet.

Re: Lead-free solder is such a PITA (rant/whinge)
On Sat, 10 Sep 2016 10:05:58 -0700, snipped-for-privacy@whidbey.com wrote:

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I didn't see any heat damage in the latest photos.
Judge for thyself:
<http://imgur.com/3NB4ALX

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Jeff Liebermann     snipped-for-privacy@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
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