You didn't say whether you looked inside the Pace tweezer plug, but if
you're going to relocate the heater wires you'll probably end up doing that
anyway.

I'm quite confident that you will find only 3 wires going to the handpiece,
as mentioned before.

If you stick the hot tip of any of the irons I was speaking of earlier onto
a cold surface, the LED will change from briefly coming on (idling), to come
on steady.. and yet, there are NO sensor leads going to the handpiece (only
because there is NO SENSOR).

The same LED action is seen when the adjustable temp control is turned
up/increased from a previously lower operating temp.. when the higher temp
is reached, the LED returns to briefly coming on (idling again).

I obviously don't need to say this, but.. hey, don't take my word for it.
Buy a used Ungar soldering iron handpiece with the same 6-pin connector on
eBag and open the connector.
It doesn't even need to be a working iron.. doesn't even need a heater, so
it should be possible to find one cheap.

I'm sure I have several extra handpieces, but don't know where to look for
them.

--
Cheers,
WB
..............


"mike" wrote in message
...
On 4/1/2013 10:44 PM, Wild_Bill wrote:
I located some notes on Ungar units, and the 6-pin connector.

I didn't write down what the actual connector pin numbers were, but can
describe them, compared to a clock face.

With the key notch at 12:00, there are 5 pins surrounding one center pin.

The 2 pins closest to the key (10:00 and 2:00) are for the variable
resistor located in the plug body of the handpiece.. I didn't write down
a value, but sketchy memory leads me to believe the value is under 25k
ohm (could be much lower).

The next pins at (4:00 and 8:00) are the heater pins.. either lead to
either pin, wire colors are likely to be black & white.

The next pin (6:00) is the handpiece earth ground pin (wire color is
likely to be green).

The center pin isn't used for soldering irons.. it's for the pump switch
in desoldering handpieces (or to actuate vacuum flow in units that don't
have internal pumps).. although some designs utilize a foot switch to
activate the vacuum source.

In the majority of temperature "controlled" soldering/desoldering irons
I've seen which are the duty-cycle type of controllers (not sensor
feedback from the handpiece), the common method of wiring the handpiece
is with a mini variable compensation resistor located in the connector
plug at the end of the handpiece or adjustable internal compensation
pots in the base unit.

The compensation adjustments were provided to allow matching of the tip
temperature range (measured with external equipment) to be adjusted to
match the temperature divisions (or temp chart) of the temp adjustment
setting controls to match approximately.
All of the duty-cycle units I've seen have only 3 cable leads for the
heater.. 2 voltage and 1 earth ground.. this goes back to when heaters
were commonly 120VAC and (simple diac/triac duty cycle) continued up to
the more recent 24V designs (isolated and ESD safe versions).
Ungar/Weller, Pace, Edsyn and others have all used this design for
various models.
The connectors and pinouts change, but generally the irons are
interchangeable as long as the voltage is within a reasonable range.

In many production assembly line scenarios, the soldering temperatures
needed to routinely be checked/adjusted (calibrated) to make sure that
the circuit board assembly temps were within a specified range
(certifications for contract work, not China assembly methods).
Some units have mechanical limiters or locks to prevent the assembly
line operator from increasing the tip temps.

Thanks for the info. The pinout is consistent with my experiments.
Sure wish I had the handpiece to look at.

My experience has been opposite yours.
My Weller EC3001 has active temperature feedback.
If you stick the tip on a cold surface, the heater power goes up.
Same for all my PACE handpieces with the 6-pin connectors.

I have some very early 120VAC PACE desoldering handpieces that are
controlled
power instead of controlled temperature and run
off a "light dimmer" in the base unit without temperature feedback.

The Weller 3-pin connector units like the TC201/TC202 have constant
heater power that's interrupted by the "magnastat" attached to the
tip reaching its curie temperature. It's a bang-bang control system
with relatively long on/off times.

--
Cheers,
WB
.............


"mike" wrote in message
...
I have a Pace tweezer soldering iron. 21V
I have an Ungar 9900AS power unit. 24V
I'd like to mate them.
The 6-pin round connector plugs in...I'm afraid to turn it on.
I found some pinout info on Pace systems,
but nothing on the Ungar.

A schematic or pinout info would save me reverse engineering the
thing.

Thanks, mike