Troubleshooting Millivolt Circuits S/Pioneer

[mike3]

Seattle Pioneer.........This is a followup from your old post (very old) that was recently resurrected and closed.

You were making mention of a device you made for powering a millivolt system to test it. I purchased a meter around 1967-68-69 that did that very thing.
Honeywell Systems Tester W720B1011. I hadn't even thought about it in 30 years, but I found it in my rollaway. Still working condition except the battery holder is damaged from leaving the batteries in. I don't think I ever used that function.

[uniservice]

Ive got mine in the truck. Bought it back in 1969. You can get a new battery holder from Radio Shack. (don't ask how I know) Also have an Annie thermocouple -valve tester that has the same millivolt test feature as the W -720 I use them both a lot on stoves and commercial gas appliances. Guess I'll will them to my boys.

[mike3]

Ive got mine in the truck. Bought it back in 1969. You can get a new battery holder from Radio Shack. (don't ask how I know) Also have an Annie thermocouple -valve tester that has the same millivolt test feature as the W -720 I use them both a lot on stoves and commercial gas appliances. Guess I'll will them to my boys.

Too funny, and the beat goes on. Seems we just can't part with old cool tools.

[Sun Dog]

I'll have to bid on them if I see them in the bottom of a box at an auction. Or buy them if I run across them otherwise....

[hearthman]

I think this BASO kit might be the current version of what ya'll are looking for. You can do the same tests with any good meter that has millivolt and milliampere capability. The enclosure explains the various tests. There are several thermocouple interrupter blocks available to facilitate attaching leads to a TC for a closed reading. My current block is the TCA-1 adapter from Field Controls which I also use when I mount spill switches on water heaters and boilers that have a TC.

HTH

[mike3]

Yes it appears to have the same functions as my Honeywell, but I can't think of a situation where i ever considered using it.

[RFisher]

I'm not really trying to hijack this thread, but I have a question about a
W720 that I'd like someone who is familiar with it to answer, and this
seemed like the place to ask.

I have a W720B1011 that was my Dad's. After repairing the damage from a pair
of leaky alkaline batteries and replacing the dead fuse, I tested it out.
When I plugged in into the 120VAC wall outlet using the 500VAC setting and the
input jacks, it read about 170VAC (what I would expect for a peak reading).

Please pardon my ignorance, but is this device intended to display peak
voltages?

I didn't find anything specific in the manual; however, the cover states that
it is calibrated only for sine waves. To me this implies that the series
resistance was chosen to scale the input by 1.414... to get a peak reading,
but I'd like some confirmation.

Thanks in advance.

[uniservice]

I think so,,,,,,,,,,,,,Never really paid attention to it in the A/C mode, just use it more for the millivolt and temperature features.

[RFisher]

Thanks for the quick response.
Could I trouble you to try measuring a normal 120V outlet with yours?

Thanks again

[Rick Gellert]

Here is how to make your own tester. This is for techs who need a simple test rig for millivolt systems.You do not need more than 3 items to get it all done. One battery, 1.5 volt nominal, two matched resistors, or light bulbs with a matched resistance of 12 to 20 ohms each.
Put one load on the hot generator and see if it is still producing 500 or more millivolts. Or use the battery and both resistors/bulbs in series. The voltage across just one of the resistors will be 750 mv. Use that to test the gas valve.

[uniservice]

Or find a W720 system tester in the bottom of a box at an auction.