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

[pedro]

On Thu, 08 Sep 2016 08:12:34 -0700, etpm@whidbey.com wrote:

>Can the valves be relocated to a cooler location?

See reply to JL for what would be involved.

>Or can you substitute more robust valves made for hot location use?

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

 

[pedro]

On Thu, 08 Sep 2016 08:17:12 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:

>What do you measure for coil DC resistance?

Missed that bit. Around 1600 ohms.

 

[Ralph Mowery]

In article <ddr4tb9bm6162hs2lupur83f8j2j5veejf@4ax.com>, me@privacy.net
says...

On Thu, 08 Sep 2016 08:12:34 -0700, etpm@whidbey.com wrote:

Can the valves be relocated to a cooler location?

See reply to JL for what would be involved.

Or can you substitute more robust valves made for hot location use?

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

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.

 

[Jeff Liebermann]

On Fri, 09 Sep 2016 16:09:10 +0800, pedro <me@privacy.net> wrote:

On Thu, 08 Sep 2016 08:17:12 -0700, Jeff Liebermann <jeffl@cruzio.com
wrote:

What do you measure for coil DC resistance?

Missed that bit. Around 1600 ohms.

Assuming 240VAC, that's:
P = E^2 / R = 240Vrms^2 / 1600 = 36 watts
That's way too high dissipation for a solenoid valve.
Are you sure those are 240VAC solenoids and some other AC voltage? Are
the solenoids run by 240VAC or some other voltage?

Also, could you check the eBay listing number? I want to see the coil
specs. Nothing found:
<http://www.ebay.com/sch/i.html?_nkw=322017672259>




--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Ralph Mowery]

In article <qfp5tbdui7tp06noacl0sjeotnm34182fu@4ax.com>,
jeffl@cruzio.com says...

On Fri, 09 Sep 2016 16:09:10 +0800, pedro <me@privacy.net> wrote:

On Thu, 08 Sep 2016 08:17:12 -0700, Jeff Liebermann <jeffl@cruzio.com
wrote:

What do you measure for coil DC resistance?

Missed that bit. Around 1600 ohms.

Assuming 240VAC, that's:
P = E^2 / R = 240Vrms^2 / 1600 = 36 watts
That's way too high dissipation for a solenoid valve.
Are you sure those are 240VAC solenoids and some other AC voltage? Are
the solenoids run by 240VAC or some other voltage?

Also, could you check the eBay listing number? I want to see the coil
specs. Nothing found:
http://www.ebay.com/sch/i.html?_nkw=322017672259

Jeff I think you are mixing up the AC and DC power formulas.

I am sure the impedance of the coil at 60 Hz is more than the DC
resistance.

That would make the wattage less than what you have calculated using a
DC equation.

A quick check of the Goyen catalog shows they draw about .05 to .07 Amps
depending on the coil at 240 volts.
That is around 10 to 16 watts. The DC resistance of the coils was not
given. The coils on many of the valves can be changed to several
voltages.

 

[pedro]

On Fri, 9 Sep 2016 15:37:02 -0400, Ralph Mowery
<rmowery28146@earthlink.net> wrote:

Jeff I think you are mixing up the AC and DC power formulas.

I am sure the impedance of the coil at 60 Hz is more than the DC
resistance.

The DC resistance averages around 1600 ohms. According to my calcs
there are around 4700 turns in the coil, so at 50Hz the impedance
incorporates a significant reactance. The coil (obviously) has a
ferrous valve plunger in its core.

They are marked 240VAC 50Hz (= our supply here in Oz) and the one I
attacked with the Dremel is marked 5W.

 

[pedro]

On Fri, 9 Sep 2016 10:03:15 -0400, Ralph Mowery
<rmowery28146@earthlink.net> wrote:

>Have you looked into another valve company ?

No

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.

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.

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

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

 

[Jeff Liebermann]

On Fri, 9 Sep 2016 15:37:02 -0400, Ralph Mowery
<rmowery28146@earthlink.net> wrote:

>Jeff I think you are mixing up the AC and DC power formulas.

Oops. Y'er right.
Big rush -> No time -> No brain -> No excuse.

A quick check of the Goyen catalog shows they draw about .05 to .07 Amps
depending on the coil at 240 volts.

Ok, that's better and less than the 5A fusing current for #34 awg.

That is around 10 to 16 watts. The DC resistance of the coils was not
given. The coils on many of the valves can be changed to several
voltages.

10 - 16 watts might get the coil quite warm if energized continuously.
Probably not enough to melt solder, but certainly will add a few
degrees to the heat from the furnace.

I don't think it's overheating from the furnace or the warm coil. It
will get hot, but not enough to melt solder. Since various other
solenoids have failed in the same manner, I don't think the failures
are caused by some kind of soldering defect. The long time that it
takes to fail might be the copper wire slowly dissolving in the
solder. However, my limited experience indicates that most of the
damage occurs immediately during soldering, not many months later.
With a 5A fusing current and the rather large inductance of the
solenoid, I don't see a high current "surge" fusing the #34 wire.

Offhand, I was thinking something else might be happening here.
Something like a sharp edge on the solenoid terminal slowly cutting
its way through the copper wire every time the solenoid is energized.
It might be 50 Hz vibration work hardening of the wire causing
embrittlement. However, these are unlikely to have also occurred in
the other replacement solenoids, that also failed. It might be the
difference in coefficient of thermal expansion between the epoxy and
the copper wire. Usually, some paper or tape wrapping will provide
room to expand, but again it would be an amazing coincidence if the
same problem appeared in a competetors solenoid.

That leaves external influences, such as line voltage glitches and
surges. Get your Dranetz power quality monitor/logger back, borrow
something, or just setup a data logger on the AC line.


--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Jeff Liebermann]

On Fri, 09 Sep 2016 23:22:39 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:

>I don't think it's overheating from the furnace or the warm coil.

Sorry, that should be oven, not furnace (in multiple places).

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

"Assuming 240VAC, that's:
P = E^2 / R = 240Vrms^2 / 1600 = 36 watts
That's way too high dissipation for a solenoid valve.
Are you sure those are 240VAC solenoids and some other AC voltage? >Are the solenoids run by 240VAC or some other voltage? "

Ummm, where is the "L" in your equation. If it is 1600 ohms DC resistance it is likely to have considerable inductance. There is also usually some type of metal core which takes it even higher.

That reminds me of a time I threw together a thermostatic control for a window unit air conditioner in a hydroponic grow room. I put the box together with a little transformer and a relay, a DC operated relay. Come to find out once it started it would not stop. I used an electronic thermostat so there was no worries about leveling it or anything, plus he liked the ability to set the timer. Turns out the SOB used a small triac and with DC it would never shut off so I had to start over. Wasn't so bad, just get a different relay and eliminate the rectifiers and filter.

But, the DC relay would not run on AC, and that had to be because of the inductance. I wound up using one for an air conditioning condensing unit, you know, like in back of the house. Typical 24 VAC job, which is what the thermostat was designed for. Put a long ass wire on it too because he wated to be able to place it wherever. he had something like 4,000 watts worth of lights and the thermostat has to be a bit away from them, and also away from the window unit.

In the end it worked but I had learned the hard way you just can't interchange relay with DC and AC coils. And damn, 1600 ohms is alot for just about any wire. Much more than that and it almost ain't wire !

 

>"Jeff I think you are mixing up the AC and DC power formulas. "

I just posted something to that effect not having seen your post. I know the guy is smart and I guess he just had a blonde moment.

 

[Ralph Mowery]

In article <cp77tbd2gk36b8o2h4977bespmnng8u6r3@4ax.com>,
jeffl@cruzio.com says...

A quick check of the Goyen catalog shows they draw about .05 to .07 Amps
depending on the coil at 240 volts.

Ok, that's better and less than the 5A fusing current for #34 awg.

That is around 10 to 16 watts. The DC resistance of the coils was not
given. The coils on many of the valves can be changed to several
voltages.

10 - 16 watts might get the coil quite warm if energized continuously.
Probably not enough to melt solder, but certainly will add a few
degrees to the heat from the furnace.

WE had hundreds of that brand where I worked and some were pulsed every
30 seconds or so and some were almost always on. Hardly any problems
with the coils. The ones that were on most of the time ran hot enough
that you would almost burn your hand. Some of them were where the room
temperature was over 100 deg F. The plant made polyester and the
process required about 300 deg C of heat. I said room, but those areas
were not occupied except to check on the equipment from time to time.

Most problems were either the rubber disk wearing out or the plunger
enlarging due to all the beating they take or the spring wearing out.
The plunger is enclosed so no way for it to touch the coil form. While
it could be something in the coil, I would think that as many that he
changed out it must be something external.

One other thing, is the coil all the way seated on where the plunger is
? If not it could be drawing enough current to burn out the wire. We
often left the coil hooked up to the conduit and just changed out the
mechanical part. Mainly did that to keep from having to go to another
floor and find the power source for the coil. Found that we needed to
stick a large screwdriver or other item in the core of the coil or a
fuse would blow or the coil would burn out.

 

[whit3rd]

On Saturday, September 10, 2016 at 9:26:40 AM UTC-7, Jeff Liebermann wrote:

...the OP reverse engineered the oven wiring and produced a
schematic of sorts. Generally quite good but a few mistakes. One was
showing an SCR keying the solenoids instead of a Triac. If it were an
SCR, it would rectify the AC going to the solenoids.

A triac can also rectify, if the gate has become insensitive (or
too responsive to noise). If you use the triac to run
an AC relay, and the relay to activate the valve, the valve is immune
to rectification (and if the relay burns up, it's cheap to replace).

Or, just replace the triac on suspicion

Even a small amount of rectification in the triac circuit will walk the
magnetic core toward saturation and remove inductive back-EMF. Next
event: the coil burns up.

 

"I'm easily distracted by paying
work. I also have a problem with some meds. "

Yeah those pesky paying customers. Why can't they just pay and leave us alone ? LOL

Those vasodilators can have side effects. But if you take one a day you could take it after supper, or even cut the pills in half. If you have a BP meter you might want to consider lowering the dosage is you are having side effects.

You know I am not an MD and I know you are not stupid enough to blindly take by advice, but I believe they pay too much attention to BP these days, at least some doctors. Think about out ancestors on the battlefield with swords and shields fighting for hours ad hours, what was their blood pressure 300/200 ? According to some doctors they should have just dropped dead. A late friend of mine who got me into doing the research on nutrition a long time ago postulated it might be a copper deficiency. And believe it or not, hypertension can also be caused by a sodium deficiency. The sodium in normal table salt is not absorbed and metabolised by the body because of the anti-clumping agent, which might also inhibit other minerals' proper usage in the body. If you use salt, get unrefied sea salt if possible. I got two kinds, one is from the dead sea and one is from up north, I usually mix them.

At least get the kind that clumps up. Evidence - back when salt would clump up in the summer and you had to put rice in it, doctors were not telling people to limit their salt intake. If you already use Kosher salt you might not have that problem but the unrefined stuff is still better because of the mineral content. Most chronic conditions are caused by mineral deficiencies. Not all, but enough to make it a concern.

I think last time I went in my BP was like 140/70. The big spread indicates the heart is working well. When the spread goes down that is a bad sign. When it goes under 40 there might be a problem. I have talked to an MD about this. Also, some would think 140/70 is high but they did not say a word about it, or even suggest any medication.

i use very little salt these days. For one this unrefined stuff tastes different. It is like it is not as strong, but it is easier to oversalt things. Take and put too much regular table salt on something and it's like oh well, but this stuff it is like UGH.

"Somewhere along the line, I simply
forgot about the inductance. "

Take a spark plug wire off your car and...

Nevermind.

 

[Jeff Liebermann]

On Sat, 10 Sep 2016 05:07:13 -0700 (PDT), jurb6006@gmail.com wrote:

"Jeff I think you are mixing up the AC and DC power formulas. "

I just posted something to that effect not having seen
your post. I know the guy is smart and I guess he just had a
blonde moment.

Not that smart yesterday. I was on hold with a customer trying to
walk them through a messy problem. I'm easily distracted by paying
work. I also have a problem with some meds. In the morning, I take a
sustained release vasodilator, which initially causes a rather radical
drop in blood pressure. When that happens, the brain goes offline or
is reduced to operating at the speed of a snail for a while. I just
took a pill for breakfast and am posting drivel while waiting for my
ISP's support people to call me back, something that has been rumored
to happen at geological intervals.

In addition, the OP reverse engineered the oven wiring and produced a
schematic of sorts. Generally quite good but a few mistakes. One was
showing an SCR keying the solenoids instead of a Triac. If it were an
SCR, it would rectify the AC going to the solenoids. That would
produce some DC on the solenoids which would raise the dissipation.
However, I didn't catch that at the time and was still concentrating
on the DC part of the puzzle. Somewhere along the line, I simply
forgot about the inductance.


--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

On Fri, 09 Sep 2016 16:08:29 +0800, pedro <me@privacy.net> wrote:

On Thu, 08 Sep 2016 08:12:34 -0700, etpm@whidbey.com wrote:

Can the valves be relocated to a cooler location?

See reply to JL for what would be involved.

Or can you substitute more robust valves made for hot location use?

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

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

 

[pedro]

On Sat, 10 Sep 2016 10:05:58 -0700, etpm@whidbey.com wrote:

Can the valves be relocated to a cooler location?

See reply to JL for what would be involved.

Or can you substitute more robust valves made for hot location use?

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

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.

 

[pedro]

On Sat, 10 Sep 2016 10:25:09 -0400, Ralph Mowery
<rmowery28146@earthlink.net> wrote:

WE had hundreds of that brand where I worked and some were pulsed every
30 seconds or so and some were almost always on. Hardly any problems
with the coils.

Ralph, should I presume that was with pre-ROHS vintage coils? As I
mentioned in my O/P, the original pair (which were pre-ROHS) both
lasted two decades. Subsequent ones were 15-18 months AND the oven
gets less use nowadays as the kids migrate outwards. Not a
statistically significant sampling for some, but sufficiently damning
from where I stand/sit.

Most problems were either the rubber disk wearing out or the plunger
enlarging due to all the beating they take or the spring wearing out.
The plunger is enclosed so no way for it to touch the coil form.

We haven't had the moving parts show any issues, just coils.

While it could be something in the coil, I would think that as many that he
changed out it must be something external.

Nothing external has changed, except our supply voltage has been
"harmonised" with rest-of-Oz i.e. reduced from the original 254V rms
down to 240V rms.

One other thing, is the coil all the way seated on where the plunger is
? If not it could be drawing enough current to burn out the wire. We
often left the coil hooked up to the conduit and just changed out the
mechanical part. Mainly did that to keep from having to go to another
floor and find the power source for the coil. Found that we needed to
stick a large screwdriver or other item in the core of the coil or a
fuse would blow or the coil would burn out.

Appreciate the question. It is seated down properly. The frame which
sits over the coil/valve assembly as part of it is actually a snug fit
(you need to slide the coil into it and align the holes, it's a press
fit) and then the frame is held down over the valve plunger "cylinder"
and screwed down. No unintended magnetic/air gaps.

There is also a "spacer" pressed into each end of the coil bobbin the
ensure it is located correctly (radially).

Pics of the valve assemblies in situ:

http://imgur.com/xGlio51
http://imgur.com/3NB4ALX

and of the coil post-Dremel (*):

http://imgur.com/An9XCk8
http://imgur.com/wH0l3eP

(*) I needed effective bobbin length/diameters to calculate turns and
hence deduce a credible wire gauge to match the known DC resistance.

 

[pedro]

On Sat, 10 Sep 2016 19:32:11 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:

Pedro... could you post your schematic somewhere or could you give me
permission to do so?

It's now at http://imgur.com/yOpwRzV alongside the pics.

 

[pedro]

On Sat, 10 Sep 2016 19:32:11 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:

On Sat, 10 Sep 2016 11:46:46 -0700 (PDT), whit3rd <whit3rd@gmail.com
wrote:

On Saturday, September 10, 2016 at 9:26:40 AM UTC-7, Jeff Liebermann wrote:

...the OP reverse engineered the oven wiring and produced a
schematic of sorts. Generally quite good but a few mistakes. One was
showing an SCR keying the solenoids instead of a Triac. If it were an
SCR, it would rectify the AC going to the solenoids.

The C106D is the device used in two places. To that extent the
schematic is correct.