Intermountain F unit sound install as per May/June N scaler magazine

[PiperguyUMD]

Hello All,

I was just wondering if anyone has tried to install a Loksound decoder into an Intermountain F unit as prescribed in the article in the May/June N scaler magazine.  I'm pretty good at decoder installs and thought this looked to be a pretty simple install for my first n scale sound decoder.  I've followed the article to a T and I'm not getting anything from the decoder.  No sound, no control, nothing. I've checked all of my connections, and all of the modifications that are required on the Intermountain pc board.  I'm stumped.  Since these decoders are so expensive, and I'm not sure what their return policy is, I'd really like to figure out what's going on!

Thanks for the help!

[JSL]

I have done a few of these most of the problems are due to motor tabs not being isolated. That would be my guess.

[kelleywpns]

I'm about to attempt this with a FTB unit.  The frame is a bit different than a F7B, so I'm going to have to attempt some milling.

Mike

[Roger Holmes]

WARNING  I have just sent two fried decoders back to LokSound and returned two defective FP7A's and one F7B to InterMountain.  These are the newest locos with soldered leads from the brushcaps to the analog board--not the brass stud design.

I have put decoders in 15 InterMountain F's of the old design and have installed many sound decoders in other units with zero fried decoders. The fault IS NOT with Bill Denton's article.  First, as is my usual, I ran the three locos on DC to confirm that they were OK from the factory.  I then tried two installations.  With each the sound came on, horn and bell responded but as soon as I advanced the throttle the units instantly blew.  A friend with a multimeter checked and found a direct short from the motor lead to the frame half on both sides of one unit and one side on both of the others.  This short wouldn't show up running on DC since it was just another path from the rails to the brushcaps.

Upon disassembly it appears that there are excessive solder blobs on the brushcaps that are contacting the frame.  I could have ground those down or isolated with Kapton tape but I wanted IM to see for themselves.  I called the factory and spoke to the locomotive repair department and he didn't indicate that they had heard this before.  I mailed them off last week along with a lengthy explanation.

I also returned the LokSound units to their address in Pennsylvania upon instructions from my retailer who indicated a 1 year goofproof warranty.  Be sure to include your receipt.

I will let you know when I hear from either.

If you were using the old board with the brass studs on the board then the above rant does not apply.

[Roger Holmes]

LokSound warranty returns go to--

ESU, LLC
Attn:  Matt
477 Knopp Dr.
Muncy, PA 17756

Be sure to include your dated receipt.  Hope this helps.

[kelleywpns]

Roger

Thanks for the info.  Curious .. have you ever attempted the install in a FT unit?

Mike

[Roger Holmes]

Mike--I haven't tried sound in an FTB but have put Digitrax decoders in the FTA and FTB.  No issues but they had the much better (IMHO) brass stud contacts which rely on mechanical rather than solder connection to the brushcaps.

[PiperguyUMD]

Just to clarify, what are the spotting differences between the older and newer units?  Thanks for the help!

[Roger Holmes]

The new units have two wires coming up through two holes in the analog board which are then soldered to the top of the analog board.  The old units have no wires but when you take out the two mounting screws you will see two brass prongs on the bottom which go through the square hole in the frame and make contact with two sprung brass clips that are attached to the brush caps.

[JSL]

This is a picture of a F7A. The wires come up from the motor tabs, the tabs need to be isolated from the frame. The wire is also very easy to scrape off the insulation which can also cause a short.

[PiperguyUMD]

Ok got it!  My B unit is from the older run.  Do I need to isolate anything? 

[JSL]

I would isolate the motors tabs with kapton tape where I assume you soldered the decoder wire to the motor?? Post some pics if possible .