Walthers Mainline GP9 w/ESU sound

[kentuckysouthernrwy]

Current project, Mainline GP9 with ESU. There is a “mother board” that the connections to the various electronics are connected to with a 21 pin connection with the sound board, labeled E.S.U. Over 5.1.RO (zero) as seen here… railroad-line.com/node/1068547. This ESU board is arranged physically different than the 21pin Series 5 as illustrated by one of the contributors in that thread. The solderable tabs are at the opposite end of the board directly under the 21 pin plug instead of the far end as diagramed in ESUs manual. I am aware that this decoder is a reduced feature board than the Loksound #5 21 pin decoder.

Overall photo of Walthers board has been added to the linked post.

Long story short…maybe… I’d like to use a TCS KA unit and want guidance on proper attachment points….

Thanks in advance for any assist.

[12bridge]

The ESU essential decoders (used in Mainline and some Scaletrains Operator) do not support keep alives at all, from any brand unfortunately.

[kentuckysouthernrwy]

Thanks for that.

[Gino Damen]

If the board is just that a board than you can just exchange the decoder. Most decoders allow you to connect the keep alive to the decoder.

[Mark R.]

Literally ANY decoder can have a keep alive attached to it .... I've even installed them on some very old MRC decoders that I use for just lighting effects in cabooses. The trick is knowing where to attach the two wires. The positive lead is the easiest as it just connects to the common blue wire used for the lights. The negative one is the tough one. There are four diodes on the board that for a bridge rectifier (the back side of the Walthers / ESU decoder in question.

There is an orange diode with two black diodes on one side of it and three on the other. You will be looking at the two on either side of the orange diode, not the third one out. With the decoder powered up, use your digital meter set to 20 volts DC. Connect the positive probe to the blue wire. Using your negative probe, check the voltage on both ends of the four black diodes I've mentioned. You will find TWO points that will provide the negative voltage giving you a reading of around 13 volts. Either one of those points is where you connect the negative wire.

Keep in mind though, that a two wire keep alive may interfere with programming the decoder. You will either have to unsolder one of the wires, or add a micro switch inline to take the keep alive out of the circuit in order to program the decoder.

Mark.

[kentuckysouthernrwy]

Thanks Mark for the input. I’m going to consult with tcsdcc also before I try anything.

[Mark R.]

This page also provides a weath of information for installing a keep alive on a variety of decoders. It will help you find the correct attachment points ....

members.optusnet.com.au/mainnorth/alive.htm

Mark.