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 Author  Topic: Tachometer connections
Sparkman65

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Post a Reply To This Topic    Reply With Quotes     Edit Message   Posted on: May 27, 2014 - 10:23am
Can anyone provide me with the electrical connections for a Weston 545 tachometer? These tachs are from PT-305 and I need to be able to evaluate them to see if they need repaired. There are 3 terminals on the back labeled 1, 2, and +_. The only other identification is Weston 545 R T-82P.
Thank you in advance


Sparkman

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  TED WALTHER

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of TED WALTHER   Send Email To TED WALTHER Posted on: May 27, 2014 - 7:45pm
Jerry;
Your up to bat, this one is your department.
Take care,
TED


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  Jerry Gilmartin

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of Jerry Gilmartin   Send Email To Jerry Gilmartin Posted on: May 27, 2014 - 8:59pm
I will check our tachs on PT658 and take a photo of how they are connected. If I recall correctly there is a little tachometer generator on each engine that sends a signal to the tach displays on both the engine room gageboard and the conn gageboard. I will ask Tom Cates, the guy that hooked them up for any further details. Also Sparkman have you asked Randy Smith, the head Motor Mac at the PT305 in New Orleans? I am pretty sure he knows how these work.

Jerry Gilmartin
PT658 Crewman
Portland OR

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Sparkman65

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Post a Reply To This Topic    Reply With Quotes     Edit Message   Posted on: May 28, 2014 - 4:26am
Jerry,
I have not personally had any contact with those on that project. I got involved because some of the tachs were sent to us to evaluate. We build some tachs here, but I have no information on the Westons at all. Sure hope I can find out what power and signal is sent to these.
Thanks!

Sparkman

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  Jerry Gilmartin

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of Jerry Gilmartin   Send Email To Jerry Gilmartin Posted on: May 28, 2014 - 5:42am
Sparkman,
I looked on the USS Pampanito website (WW2 sub in San Francisco) and found this info about the Weston 545

0-8 R.P.M. Hundreds, Use with Mod 724 Magneto, Speed Ratio 1:2, Model 545, Weston (this is 3 7/8" wide x 4.5" tall)

Tachometer Magneto, Type C4, 200 ohms, 6 volts per 1000 RPM, Weston that go with these meters. (4)

http://www.maritime.org/wish/meters.htm

Tach on Pampanito


Sending unit on Pampaniito



Also I looked on Google and found a Weston Tech manual on sale on eBay. Here is the link and some screen captures from the book. You may want to buy it! Jerry

http://www.ebay.com/itm/vintage-WESTON-AVIATION-INSTRUMENTS-manual-WWII-War-Department-/171238961134

Cover Page



Magneto cutaway for tach generator


Instructions for Weston Model 545 Tach



PS TED I think I slam-dunked this question!
Jerry Gilmartin
PT658 Crewman
Portland OR

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  TED WALTHER

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of TED WALTHER   Send Email To TED WALTHER Posted on: May 28, 2014 - 7:19am
Jerry;
Yes you did slam dunk that one my friend, but that's what snipes are for! :0)
Take care,
TED


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Sparkman65

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Post a Reply To This Topic    Reply With Quotes     Edit Message   Posted on: May 28, 2014 - 7:35am
Jerry,
I think that manual may be the way to go. I need to know more about the internal construction as I believe corrosion may be the culprit. I opened the indicator and I can get needle deflection from the voltage at my ohmmeter probes. I don't have continuity to the external post on one side. If I apply the negative lead to the +/- post internally and the positive lead to the #2 post internally, I get a deflection. However, if I move the positive lead to the external #2 post I get nothing and the resistance is infinite from the #2 internal connection and the external post. Time to do a little more digging!

Sparkman

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Sparkman65

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Post a Reply To This Topic    Reply With Quotes     Edit Message   Posted on: May 28, 2014 - 9:18am
After digging some more using the pages Jerry provided as a guide, I believe that the problem is with the bridge resistors internal to the meter. Some of them are open somewhere in the windings.
Does anyone know where I might send these to get them repaired?

Sparkman

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Sparkman65

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Post a Reply To This Topic    Reply With Quotes     Edit Message   Posted on: May 28, 2014 - 11:59am
I still need to acquire the manual for this unit to learn how to properly calibrate it. However, it seems that the signal can be applied to the +/- terminal and either the #1 or #2 terminal.

The bridge resistors in these meters consist of thin wire of a specific AWG size and length wound on a spool. One of the meters has a hand-written note inside that shows one coil to be 430 Ohms and the other of 27 Ohms. Theoretically, 166 feet of AWG 44 wire should be close to 430 Ohms and the other spool should take about 10.4 feet. I will try to duplicate the coils and post the results in case someone else needs the information.

Sparkman

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