Ken H

My thoughts about leaving the 104 capacitor in the circuit is because my Hornby 0-6-0 didn't come from the factory with the two inductors in series on the grey and orange leads from the decoder to the motor, but it did have the 104 capacitor in parallel with the decoder wires to the motor. I've lost five decoders (two Soundtraxx, two Digitrax, and an MRC sound decoder) during this project, and I wonder if Hornby didn't feel the 104 capacitor was still needed. I just installed a new capacitor and so far it runs on DCC, and the lights work. I'll see if I lose any more decoders.

I have tried Soundtraxx Economi UK, and Digitrax SDH167D. Both worked beautifully for a day and a half, and then died. And this is before I added a 3mm headlight and tail light (both with resistors). I'm now running using a Digitrax DH126PS. It runs the Hornby fine, except I burned one out when a tiny component in it burned, and the lights went out. But the loco kept running. I've replaced the Digitrax with another DH126PS, and it is handling the motors and lights fine. I just wonder if that 104 capacitor shouldn't be across the motor leads. Something is killing my decoders, but it's taking its time. Now my module group is wondering what I'm doing wrong. I installed a MRC SOUNDER Steam Sound Decoder to add sound, since the Digitrax decoder doesn't do sound. The Sounder did fine for 10 days, and then died. It's on its way to New Jersey. This is all taking place on my test track, powered by a NCE PowerCab.

I love my converted Hornby "Thomas". One problem, it keeps killing DCC decoders.

Did the soldering today, and cut all the leads to a reasonable length. Got out my Bachmann Command Control unit, and somehow got it to work in DCC. I was able to get the 0-6-0 to run a bit, so the decoder definitely changed the loco to DCC. Tomorrow I'll see about sound, when I run it as #3 on my On30 tracks using my NCE Power Cab. Ken (in SoCal)

Day Two: I have now pretty much finished figuring out how to fit that Digitrax SDH167D sound decoder into the OO Hornby 0-6-0 Thomas. A lot of wires hanging out to cut and replace. Thank God for your article' Art (and the art in your article) See below how it stands now. The speaker (a nice 8 ohm one that comes with the Digitrax decoder) will go in the bunker under the wood. The 330uf keep alive will hide in the boiler. This decoder is big. The decoder itself is double stickied to the Engineer's side of the inside of the shell, just clearing the wheels. I'll paint any of the blue Digitrax shell that shows green. Next comes figuring out which wire solders to which wire. (Love how the British pronounce SOLDER the way it's spelled). We Americans pronounce it with the L silent. Hope to hear from my friend who does great work making things out of other things. He felt a On30 scale Porter cab (like my LUCY (named for my great grandmother) would be great (and has an extra one) but I think it would be too big). Of course OO 1:76 scale cab doors are about 4' in O scale (1:48). Boy, there are a LOT of wires. Hope it all works. Ken (in SoCal)

Thank you for this excellent answer to my problem. I was convinced that I needed those inductors (labeled capacitors), but my R30039 Thomas didn't have them. Now I know why. One Question: In the Fig. 8 above, you show the 104 Capacitor still in place. Will that hurt anything? You said it wasn't needed for DCC. I'm installing a Digitrax SDH167D sound decoder which also converts the 0-6-0 to DCC. There is plenty of room in that boiler. This should be fun. I'm adding it to my On30 stable. A friend will change the cab for a larger one, and it should look good as a left over WW1 loco.

Good point. And strange. That is the way the Loco came to me. I bought it new on Amazon. I only replaced the one missing S.1014 screw after one flew off during a stall test. The Service Sheet No. 139 (dated February 1987, see below) does show the "bit sticking up" pointing up. Also, in this fairly clear blowup, I do believe you can see that the coupling rod screws are indeed slotted, even though the one I got maybe a month ago had them hex. This model was first made in 1987. I tried to buy some S.1229 screws from Peter's Spares, but at checkout realized I was being charged $50 for 4 S.1229 screws. I have some spares of those. Peter's Spares said the S.1229 (for the overlapped Couplings) were Hex, but oh, that price. My brain hurts.

I ordered some of the Coupling Rod screws because one disappeared during a motor stall test. They turned out to be round head with a screwdriver slot (see top photo), not the Hex head I expected.

Yes, I am having trouble with the Hornby part numbers. I did add a zero. It should be R7150. *I've edited just now, a month later.* I finally looked at the pin out for the decoder. Six pins and no sign of a speaker out, so no sound. Too bad. DHL got it to me in 3 days from Heathrow, and it's useless. I'll go to my local train store. The guy knows DCC and can get my R30039 Thomas running and sounding great. Now all I need is a bigger cab for my O scale crew. Being On30, at least the rail gauge is right. Thanks for the reality check.

This is the Amazon description of the R7150: "The Hornby TTS (twin track sound) decoder offers a great alternative for those modellers that would like to add sound, but at a more affordable price. Our TTS decoder offers a minimum of 16 realistic sound functions, With many specific to the chosen model. These can include whistles, horns, start-up, idle, cold start, in motion sounds and many more. The decoder also possesses all of the features attributed to our popular R8249 decoder." Unfortunately, the Hornby Train Restorations site promises answers, and tells you to write them. Strangely they have a box in which to write your questions, but I can find no way to send that question. It lacks a SEND button. Not even just hitting RETURN/ENTER works. They also include an email address: service@Hornby-railway-trains.co.uk. I've written to this email address several times in the last two weeks. No reply even though I included my email address as requested. If there is no sound, I guess I'll have to return it. Too bad, because it took only about three days to get here (SoCal) from the UK. Other Hornby decoders sound like they have better features.

The product description is: "The Hornby TTS (twin track sound) decoder offers a great alternative for those modellers that would like to add sound, but at a more affordable price. Our TTS decoder offers a minimum of 16 realistic sound functions, With many specific to the chosen model. These can include whistles, horns, start-up, idle, cold start, in motion sounds and many more. The decoder also possesses all of the features attributed to our popular R8249 decoder."

I'm intrigued by the R7150 decoder. It says it is a sound decoder and has all the features of the Hornby standard R8249. Does this mean you get both a DCC controller and sound in the one package? When I look at the instructions for installing any decoder in my R30039 Thomas loco, the drawing ... is very different from what I see before me. One capacitor instead of three illustrated. I'll get my R7150 decoder on the 10th. I'll see what it has for instructions. I've written to Hornby Loco Restoration but the online comments box doesn't have any sort of way to SEND, and the email address given doesn't seem to actually work.