Bachmann Spectrum 82505, 4-8-2???

Model Railroader Electronics and DCC
1

Hello everyone,

Another newbie question. I just won a bid for a Bachmann Spectrum 82505, 4-8-2. I believe it is DCC ready. The seller sent me 2 pictures of the circuit card installed in the tender. How do I go about finding the correct decoder for this model?

Thanks,

Vic

2

Vic,

I’m assuming you are talking about a motor-only decoder. I’m a huge fan of TCS. Here’s a link to the TCS website that shows a pictoral for installing one of their DP5 decoders in a Bachman :

http://www.tcsdcc.com/Customer_Content/Installation_Pictures/HO_Scale/Bachmann/Spectrum_4-8-4_Heavy_Mountain/Bachmman_Spectrum_4-8-4_Heavy_Mountain.html

Tom

3

Thanks Tom, I am very new to all this DCC stuff. So How do I go about putting sound in this?

Thanks,

Vic

4

Well, Vic, there’s a pictoral on the TCS website for that, too:

http://www.tcsdcc.com/Customer_Content/Installation_Pictures/HO_Scale/Bachmann/Heavy_4-8-2/Heavy_4-8-2.html

Loksound and Soundtraxx are two other motor-only and sound decoder brands. Between the two I like Loksound because - like TCS - it has better motor-control right out of the box than Soundtraxx. But…everyone has their personal preferences.

Tom

5

I was going to say, cut the caps but I see it says to cut them. Some say the green things are resistors but they are 4.7 henry inductors. They are labeled, L1 and L2. Some remove them and put in a piece of wire. They are essentially zero resistance. I have measured them.

Rich

6

They’re 0 ohms to DC - but not to AC. Which is why they are there - combined witht he capacitors it supresses high frequency AC, aka RF emissions. But it also supresses the high frequency decoder drive from a good decoder - probably why the old Bachmann DCC on-board decoders didn;t use high frequency silent drive. ANd it also supresses the BEMF signal, so a decooder with BEMF can;t do its thing properly. You only have to remove the capacitors, which require no rewiring since they are in parallel witht he motor or connect each motor lead to ground. You can remove the inductors, but they have to be replaced with jumper wires as they are in series with each motor lead and if you just cut them out, no power will get to the motor.

–Randy

7

Randy is correct. When Bachmann added Tsunami value decoders to their offerings, they forgot to take out the inductor which really messes with BEMF. I complained about this years ago and we heard zip from Bachmann about a production fix.

But the inductor is needed for european electrical standards to prevent radio frequency interference noise.

8

One thing to keep in mind is I believe as shown in the link Tom posted, both the light and heavy USRA 4-8-2 models require what’s called a “UK” decoder harness, since the eight-pin receptacle is set up 90-degrees from the way most US decoder receptacles are set…that is, the receptacle is set with the long sides of the receptacle parallel to the long sides of the tender, instead of cross-ways.