Author Topic: solder pads on ESU 73199 loksound select direct micro OEM for TCS KA3 keep alive  (Read 715 times)

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smunderloh

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Mr. Peteski has done a wonderful job of discussing the 73199 and drawing a diagram. Could you please post a picture of the 73199 and point out/label the exact pads that correspond to the red and green pads. I am not able to figure out how the diagram translates to the actual decoder. Thanks!

RBrodzinsky

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There are no pads for those.  You need to use the identified components and solder and solder to the sides of the capacitors. (The 4 green circles indicate the ground plane of the PCB).
Rick Brodzinsky
Chief Engineer - JACALAR Railroad
Silicon Valley FreeMo-N

smunderloh

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Thanks for responding. Could you please assume that I know nothing of circuit boards, etc. I don't know what a PCB (primary circuit board?) is. I have a diagram of the 73199 and it has a wheel for the right track and a wheel for the left track leading to the little copper pads. If I solder the KA3 to the first set of pads is that correct? Blue wire to the right track and black to the left track pad? Thanks for your patience.

jdcolombo

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OK.  Look at Peteski's photos of the 73199 in his post.  (here: https://www.therailwire.net/forum/index.php?topic=44324.0).

The negative wire from the KA-3 (the black striped wire) can be soldered to any place where there is a green dot or rectangle.  On the top of the decoder (the first of the two photos of the 73199 in Peteski's post), you will see two green dots on the RH side of the photo; you can solder the negative wire to the large board traces where these dots are, but you will need to scrape off the insulating paint to do so (use a #11 hobby knife blade and scrape until you see bare copper; scrape away just enough area to solder the wire to).  Alternatively, you can solder the negative wire to the green-marked pads where the capacitors (the rectangular yellow things] at the top of the photo are attached.  You won't have to scrape away any insulating paint to do this, but make your soldering journey quick: strip and tin about a 1/16" end of the negative KA-3 wire, then hold the wire on the pad where the capacitor is soldered and touch your hot, tinned iron to the wire so that it solders to the pad and edge of the cap.

Now for the blue wire.  If you want your keep alive to power the motor, which I assume you do since you're using a KA-3, you must solder the blue wire of the KA-3 to one of the two red spots marked on Pete's photo.  I'd use the far right side of the black diode on the right side of the decoder that Pete has marked with a red rectangle, since that is easiest to get to.  Again, make it quick - strip and pre-tin the blue wire, touch it to the pad where the black cap is with a hot, tinned iron.  No more than a second (it should take only a half-second if you are doing it correctly).

Done.

John C.
« Last Edit: June 02, 2020, 03:10:20 PM by jdcolombo »

smunderloh

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Thank you, John, for making it clear and detailed. I very much appreciate you taking the time to help. I have spent a lot of time trying to figure this out and now I know what to do.

JanesCustomTrain

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MAYBE, trial and error soldering first on an old and/or defective piece of PCB before you fry your decoder, just a thought.

Jane
I don't want to start any blasphemous rumors
But I think that God's got a sick sense of humor
And when I die I expect to find Him laughing...

RBrodzinsky

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Oh - and PCB=Printed Circuit Board
Rick Brodzinsky
Chief Engineer - JACALAR Railroad
Silicon Valley FreeMo-N

peteski

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Looks like things are under control here - thanks guys!
. . . 42 . . .

smunderloh

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Thanks for  all the help and comments. To allay Jane's fears, I will have a biomedical technician at the hospital do the soldering. I agree that the length of time it took to get me to understand where to solder did not inspire confidence in my electrical abilities.  Thanks again to Petreski and John C.

JanesCustomTrain

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 ;)

Jane
I don't want to start any blasphemous rumors
But I think that God's got a sick sense of humor
And when I die I expect to find Him laughing...

smunderloh

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I have installed 2 KA3's in Atlas n scale locos with the ESU 7133 decoder. The soldering is pretty meticulous, but both worked with great results.
As stated above, you will need to place the KA3 in a following car which is easy to do.  Thanks again for all the help.

smunderloh

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Correction--the decoder is ESU 73199