Decoder problem I think?


goscrewyourselves

goscrewyourselves

I'm the one
I few days ago I installed a TCS decoder into a Kato F7 engine. The engine runs beautifully so long as I leave the shell (body) off of it. As soon as the shell is put on the engine hesitates and barely moves although it sounds as though everything is running as it should. By that I mean the motors are running and the wheels are turning - just not moving or, when it finally does move, is very hesitant and does not travel far, a few inches if that.

Bottom line is in simple terms - when the shell is off the engine it runs flawlessly. When the body is on the engine, you may as well say it doesn't run/move.
 
Sounds like the shell is trapping the flywheels. When you installed the decoder, did you put it on top of the existing motor? Also, stray wires may be rubbing against the flywheels. Check your clearances of moving parts.
 
It was a "drop in decoder" so there were no wires to attach - removed the original light board and installed the TCS in its place which is on top of the motor like this:





How do I check the clearances with the shell on? All I can really see to check with the shell on are the trucks and they move freely.

When the shell goes on, it seems to slip on fairly easily and it doesn't "feel" as though it is hitting anything but obviously it must be.
 
D&J RailRoad said:
Sounds like the shell is trapping the flywheels. When you installed the decoder, did you put it on top of the existing motor? Also, stray wires may be rubbing against the flywheels. Check your clearances of moving parts.
Click to expand...

That was my first thought, too, as I have a couple of locos that I converted over to DCC where I had that exact problem. BUT, if it's a drop in decoder, that shouldn't be the issue. Hmmm...

Check to make sure that there's nothing in the shell that might be shorting out the decoder in some way. Some piece of foil or something that was designed to work with the stock light board that needs t be taking out. Also, try running the loco in stages of shell installation. Just place the shell on like a hat and run it to see how it goes, then slowly press it down a little further to see where the problem starts.
 
A: I was wondering why the board is sticking up like that at one end?
B: Are there bare contacts on the underside of the board that are shorting against the motor casing or chassis with the shell on?
C: Does the LED lightup with the shell on?
 
That board sticking up looks suspicious to me too plus the fact that it's N scale.
 
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Thanks Guys and yeah, the board sticking up has me wondering as well. I may need to remove it and try again with the install. One of the issues I had with the install was getting the 2 brass rails to re sit properly, sit flat. Perhaps one end of the rails lifted making the decoder stick up. I'll re visit that as well.

KB02,

I'll give the "put the shell on in stages" a try and see if that tells anything.

Toot'n,

B. I don't think so, the only part of the engine that needs to be insulated is around the motor tabs from the rails to the motor tabs and that was done.

C. Yes the light does illuminate.

Although I have only done 5 or 6 DCC conversions, all have been on Kato engines and all have been done with TCS drop in decoders. This is the first one I have had issues with.
 
K1315.png


;);););)
 
Okay, the problem of the decoder sitting up on the right side is due to it "slipping out" of a very small lip that is suppose to hold it flat and in place. I don't know if the TCS decoder is a little thicker than the original light board but that clip has trouble getting enough grab on the decoder to hold it down. The slightest bump causes the decoder to slip out of the "clip" and the rails push the whole she bang upwards as shown in the pictures.

Now, as the track power tabs are supposed to connect to the bottom of the rails, if the rails aren't being held in place where they should be then there is the possibility that the right hand side track power tabs aren't making contact with the rails; thereby, causing the hesitation - possibly.

The only way I am going to find out if that is the case is work out a way of keeping the decoder beneath the little plastic clip/tab and see if the hesitation remains.

As for the thing running well without shell on, I am now guessing that I am knocking the decoder out from under that clip when I put the body/shell on.

Oh and sorry guys but, I'm all out of hammers of any size unless I'm working on your trains ;)
 
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Tony, remember: If it doesn't fit, force it. If it breaks, it needed replacing anyway.
 
Terry,

Yep and that's more or less what I have had to do to get it beneath the clip/tab thing - force it under it and hope that it holds and hope that I don't break anything in the process.

The problem I see with the tab on the F7 is it seems to be tapered from back to front, meaning the opening at the front is about 1 mm high while the rear of the opening is only maybe .75 mm. So, the decoder slips into the front of the tab but only goes back about half way meaning it is only being held in place by about a mil of the tab, if that makes sense.

This maybe an isolated issue and I got unlucky or it maybe something that is particular to the Kato F7 as the other Kato engines I have, and done conversions on, had the same setup but the decoders slide all the way in and were secure or they had actual slots into which the decoder slid which, in my humble and very novice opinion, seems the best method.
 
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