Re: ANTIQUE SIMPSON / MINNEAPOLIS-HONEYWELL MILLIVOLTMETER, MODEL W129A2X1

I found additional information on the meter itself.

Patent Numbers: 2,051,399 & 2,433,165, Simpson Electric Co. Chicago, IL USA Model 127

Any >

I have recently acquired a working, antique Simpson / > Minneapolis-Honeywell millivoltmeter, model W129A2X1. > This unit is extremely old and I have had a difficult time tracking > down any information pertaining to the unit. > > On the inside of the case is a condensed chart with reference to > thermocouple and powerpile readings -- I would presume this unit was > designed to work with a boiler. > > I am hoping someone here may have or know of somewhere/someone that I > can obtain an operator's manual for this unit -- if there is such a > thing. > > I have recently contacted both Simpson Electric and Honeywell, but have > yet to hear back from either regarding this interesting device. > > As you can see from the attached photos, the casing is somewhat > delapidated, but is still in a fairly sturdy condition. I took the > liberty of dismantling the unit in order to replace the four lead wires > as the originals were basically crumbling apart. I do not know whether > or not the supplied aligator clips are the originals or not. On the > bottom of each, they sport the following imprinting: > > Mueller Elec. Co. > Cleveland Ohio U.S.A. > 60 Series > > Any information provided will be greatly appreciated. > > Thanks in advance! > >

After looking through the available data sheets for Model 127 on

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I think I may have found something...

While the specs may have changed slightly or even significantly over the years, I did notice something of interest...

The unit currently described in the

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describes the following:

DC Millivoltmeters, Self Shielding Movement Option 1: Range: 0 - 50 Approx. Impedance (Ohnms) @ 60 Hz: 10 Model/Size and Catalog Number - 2-1/2" Model 127: 06990

Option 2: Range: 0 - 100 Approx. Impedance (Ohnms) @ 60 Hz: 20 Model/Size and Catalog Number - 2-1/2" Model 127: Available on special order.

With regards to the unit I recently procured, it would seem to have some unique design features that may not necessarily be available on current models offered by Simpson Electric, Co.

The meter in my possession is of the 2-1/2" variety and is accompanied by four (hardwired) test leads attached to four connecting posts on the back of the meter.

According to the accompanying detail within the lid of the unit's case...

There is a plain (common) wire. This would have been connected to the inner thermocouple lead or white powerpile lead.

There is a black (0-50 MV) lead. This would have been the outer thermocouple lead.

There is a red (0-500 MV lead. This, in conjunction with the yellow (meter) lead would be connected to the red powerpile lead.

There is a yellow (0-1000MV) lead. This, in conjunction with the red (meter) lead would be connected to the red powerpile lead.

From the detail listed on the underside of the lid, this particular unit seemed to have been used for diagnostics with regards to the thermocouple and/or powerpile of a boiler (based on my google research). Other part numbers in the printed on the detail seem to reference various (deprecated) Honeywell thermocouples and powerpiles.

Once again, I would be grateful for any additional information that anyone may have regarding this unit.