METCAL SP200 tips failing. Failure mechanism?

Guest
Have been using METACL SP200 solder stations for the past few years.
Curious as to the mechanism of the tip's failing.
Have had a batch of them that don't last more than a few weeks.
All of the broken units heat up to approx 250C, hot enough to burn
your fingers but no goos for soldering.
Checking the heater coil resistance shows no DC resistance between
faulty ones and new working ones.

Fault follows faulty tips when swapped to other base units and wands.

Any thoughts?

Louiiv
 
On 22 Jan, 16:09, 98ba...@oink.co.uk wrote:
Have been using METACL SP200 solder stations for the past few years.
Curious as to the mechanism of  the  tip's failing.
Have had a batch of them that don't last more than a few weeks.
All of the broken units heat up to approx 250C, hot enough to burn
your fingers but no goos for soldering.
Checking the heater coil resistance shows no DC resistance between
faulty ones and new working ones.

Fault follows  faulty tips when swapped to other base units and wands.

Any thoughts?

Louiiv
Click to expand...
I'd send them back to Metcal. I've had a couple of MX-500 cartridges
fail in the same way, but that was after a year or so. I don't know
what the mechanism is, though.

Leon
 
On 2009-01-22, 98bacon@oink.co.uk <98bacon@oink.co.uk> wrote:
Have been using METACL SP200 solder stations for the past few years.
Curious as to the mechanism of the tip's failing.
Have had a batch of them that don't last more than a few weeks.
All of the broken units heat up to approx 250C, hot enough to burn
your fingers but no goos for soldering.
Checking the heater coil resistance shows no DC resistance between
faulty ones and new working ones.
Click to expand...
assuming "no DC resistance" means "no difference in DC resistance"

"feels" like the temperature sensor part is faulty.
 
Jasen Betts wrote:
On 2009-01-22, 98bacon@oink.co.uk <98bacon@oink.co.uk> wrote:
Have been using METACL SP200 solder stations for the past few years.
Curious as to the mechanism of the tip's failing.
Have had a batch of them that don't last more than a few weeks.
All of the broken units heat up to approx 250C, hot enough to burn
your fingers but no goos for soldering.
Checking the heater coil resistance shows no DC resistance between
faulty ones and new working ones.

assuming "no DC resistance" means "no difference in DC resistance"

"feels" like the temperature sensor part is faulty.
Click to expand...
Probably right.

The Metcal works by feeding RF energy to a tip that consists of a copper
core plated with a layer of ferromagnetic material that has a specific
curie point. The plating heats up, loses its magentic properties, and
the current flows in the copper with low loss and little heating until
some heat is removed from the tip.

It sounds like you have a batch of tips on which the plating is delaminating
from the copper. The plating heats up, but the heat isn't properly coupled
to the rest of the tip.

BTW, measuring the DC resistance is just telling you the resistance of
the RF coupling coil. It has nothing to do with the actual heating
mechanism, except of course, that if it's open, the system won't work
at all.

-- Dave Tweed
 
Leon wrote:

On 22 Jan, 16:09, 98ba...@oink.co.uk wrote:
Have been using METACL SP200 solder stations for the past few years.
Curious as to the mechanism of  the  tip's failing.
Have had a batch of them that don't last more than a few weeks.
All of the broken units heat up to approx 250C, hot enough to burn
your fingers but no goos for soldering.
Checking the heater coil resistance shows no DC resistance between
faulty ones and new working ones.

Fault follows  faulty tips when swapped to other base units and wands.

Any thoughts?

Louiiv

I'd send them back to Metcal. I've had a couple of MX-500 cartridges
fail in the same way, but that was after a year or so. I don't know
what the mechanism is, though.

Leon
Click to expand...
I second that suggestion. They do replace faulty tips provided they don't
have any pliers marks on them and the plating is not cracked from bending
etc.

Chris
 
On Fri, 23 Jan 2009 23:23:19 +0000, Chris Jones <lugnut808@yahoo.com>
wrote:

Leon wrote:

On 22 Jan, 16:09, 98ba...@oink.co.uk wrote:
Have been using METACL SP200 solder stations for the past few years.
Curious as to the mechanism of  the  tip's failing.
Have had a batch of them that don't last more than a few weeks.
All of the broken units heat up to approx 250C, hot enough to burn
your fingers but no goos for soldering.
Checking the heater coil resistance shows no DC resistance between
faulty ones and new working ones.

Fault follows  faulty tips when swapped to other base units and wands.

Any thoughts?

Louiiv

I'd send them back to Metcal. I've had a couple of MX-500 cartridges
fail in the same way, but that was after a year or so. I don't know
what the mechanism is, though.

Leon

I second that suggestion. They do replace faulty tips provided they don't
have any pliers marks on them and the plating is not cracked from bending
etc.

Chris
Click to expand...

The tip-caddy/holder is often the culprit. The center pin socket gets
carbonized or such. I have seen it happen more than once.
 
98bacon@oink.co.uk wrote:

Thanks for the replies.

Having taken one apart to see how it functions has not left me with
any new thoughts. Just a slug of metal with a wire wrapped round it.

Info from the net suggests the base unit detects when one part of the
tip passes it's Curie point. OK but still unsure how this can wear
out or fail.
De-lamination as suggested may be a cause and I shall have a closer
look.

The tips I am using now are higher temperature parts for Lead free
soldering so I guess there
needs to be a different material used with a higher Curie point.

It is interesting (and beyond my) how the magnetized iron holder
indicates to the base
unit to reduce the tip temperature. If this function is not working
the tip will be at
max temp all the time and could be the cause of some of my tip
failures.
Click to expand...
I haven't looked into the lower frequency tips, only the 13.56MHz ones like
PS2E and MX500. You can find out how they work by looking up their
patents. I think that the original patents probably ran out a couple of
years ago so anyone could build them now, which might partly explain why
they shifted production to China, cost-reduced the design and dropped the
price significantly.

In the original scheme for the PS2E type 13.56MHz tips, the tip does not
need to send any information back to the RF source. I think they might
have added some fancy stuff later on to detect when the iron is not being
used, but that is not essential to the temperature control. I think that
they run a constant RF current through the insulated silver plated copper
coil which induces currents in the metal slug, and depending on whether the
metal is below or above the curie point, the current either flows in the
copper core (causing little heating) or in the resistive plating (some sort
of nickel alloy IIRC) which would cause much more heating. It is a while
since I read the patent so I can't remember.

I think that in some cases, the failures are caused by the fibreglass
sleeving over the heating coil getting cracked causing a short circuit. In
particular I think this might be what happens when people change tips using
pliers. I don't really know.

Chris
 
Thanks for the replies.

Having taken one apart to see how it functions has not left me with
any new thoughts. Just a slug of metal with a wire wrapped round it.

Info from the net suggests the base unit detects when one part of the
tip passes it's Curie point. OK but still unsure how this can wear
out or fail.
De-lamination as suggested may be a cause and I shall have a closer
look.

The tips I am using now are higher temperature parts for Lead free
soldering so I guess there
needs to be a different material used with a higher Curie point.

It is interesting (and beyond my) how the magnetized iron holder
indicates to the base
unit to reduce the tip temperature. If this function is not working
the tip will be at
max temp all the time and could be the cause of some of my tip
failures.
 
<98bacon@oink.co.uk> skrev i meddelelsen
news:df9675ca-094a-47e3-abc8-f11d31742b03@a12g2000pro.googlegroups.com...

Any thoughts?

Louiiv
Click to expand...
The original Chinese manufacturer went tits-up due to the financial crisis
so they found an even cheaper one somewhere worse than China; now they are
stuck with an entire containerload of crap. Have them replaced under
warranty and hope that they are out of the bad product ;-)
 
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