Hello, I plan to convert my PRR SD9 to DCC. Which standard (non sound!) decoder you succesfully put to this engine?
Here is a pic:
I plan to use TCS decoder, but Digitrax is also available in this shop where I plan to order it.
I wanted to put plug-in TCS DP2X decoder, but I think it is to thick to fit under long hood. So, some smaller one may be needed.
Thanks!
DZ123P will work nicely.
David B
You could try calling Tony’s Train Exchange and asking them.
One decoder you may want to take a look at is the DH165A0 by Digitrax. In this loco, it would be a simple board replacement.
Remove the two screws.
Pull the plastic caps off of the tabs where the wires are attached.
Remove the wires (they are not soldered) and attach them to their respective tabs on the DH165A0.
Put the plastic caps back on the tabs.
Put the board in place and tighten the screws.
Misson accomplished. This decoder has regulated head and tail light outputs so the existing bulbs should not need to be replaced.
This decoder also accepts the Digitrax Soundbug should you decide you want to add sound later.
I just installed one in my P1K RS-2 instead of the DH165L0 which is the one that attaches to the 8 pin socket. The price for either decoder should be less than $30.00.
Vernon
That’s what I have in both of mine, The Dh16xIP won’t fit unless you can extend the pins.
I would like to know which sound decoders would work though.
If this is an HO engine, the Digitrax DH163L0 should drop in. It is made for P2K engines and has a special setup to plug on top of that DCC plug in your picture. It also has the proper resistors for the lights. I use them on my P2K GP7 and GP9’s…
Jim
Contrary to some of the replies, a Digitrax DH163LO will not fit in a SD7/9. If you look closely at the photo you seethat there is no room to plug the decoder into the socket. To the left of the socket is a set of diodes and a resistor that stick up too much for the socket to be plugged in. The board is also significantly longer than most later light boards. The wires will be too short to simply reconnect to the replacement decoder board. Your best bet is to remove the factory board and hardwire a decoder/harness in its place. While you have everything taken apart grind/file of the nubs and protrusions on the weights so the decoder fits better. I have 4 SD7/9 in which I installed decoders this way. Trust me, the 163LO will NOT fit.
I agree with JK. Both my SD7s have the early Digitrax 123P. The DZ123 is a better choice from what’s avail today. The bulbs need to be changed to 12V. The DH163LO is great for the newer P2Ks and it allows to keep the stock 3V bulbs. This decoder is made to replace the board and the units wiring is in the plug not the other way around. Just too bad it doesn’t work on the early SD7.
You also need to make sure that there is not protruding lugs inside the top of the shell. The clearance is fairly tight for the plug.
&n
The other thing that seems to be true is the circuit board in the P2K SD9s works kind of buggy when you plug a decoder into the board. You get better loco performance if you remove the circuit board entirely and hard-wire a decoder in its place.
I’d recommend replacing the board with a Train Control Systems A6X decoder. It’s $27 from Litchfield Station, has Back EMF and dithering for nice slow speed control, and it includes on-board 1.5V power for 1.2mm micro headlights.
As mentioned, while you’re doing the install, smooth off the metal weight of all the little doo-dads that just get in the way of the decoder seating down nice and flat on top of the cast weight. It’s a fairly straightforward cut-and-fit job, and you should get some decent performance with this decoder in this loco.
Hello, thanks on your answers! I will then try to order A6X, as it is cheaper than DZ125PS, and with Digitrax I would also need bulb replacements. Only drawback is that A6X does not have BEMF, if I understood right from TCS site, even though Joe said it DOES have it.
While we are at new Digitrax DZ125PS, in its PDF there is confusing info.
Look at this link: http://www.digitrax.com/ftp/DZ125PS.pdf
On page 1 it is said:
“Scaleable Speed Stabilization (Back EMF) with simple setup & 1024 level resolution.”
but, on page 5 you can read:
"Normal Direction of Travel is controlled by CV29. See your decoder manual
for additional information on the settings for CV29.
This decoder does not support Scaleable Speed Stabilization (Back EMF)"
Would you say this BEMF feature is worth few $$ more?
Hey, Joe, can you explain what would be the “little doo-dads”? As english is not my native, I cannot fully understand this lingo! [:D] Sorry!
“Little doo-dads” would be the following: 1) the are 4 raised posts that the orginal light board are screwed into - remove them since you are replacing the light board; 2) there a 3 bumps that the light bulb wires are pinched into that hold them in place - remove them also and electrical tape to hold the wires in place.
The Digitrax DH165A0 is a board replacement for this loco and includes BEMF along with regulated front and rear light output (no bulb replacement). I believe the list price is around $28.00.
Vernon
I have DH123Ps, The engines run good, and the lights work fine. I guess it’s because I’m using the factory resistors for the lights. I got the DH123s for 23 bucks a piece
I read something about them having different circuit boards based on the run. Mine are green in both of mine.
Actually, you need to read the “What’s new” section of the TCS site, which says:
BEMF! We are delighted to announce that most of our decoders are now shipping with BEMF.
Decoders now Shipping with BEMF:
A6X, DP2X, M1, MC2, MC4, MC6, T1,T4X, T6X now the ADSD4 and CN as well!
Note they list the A6X! With the P2Ks, the BEMF is not absolutely necessary, but it will turn these locos into exceptional slow-speed runners if you use BEMF. I also set the TCS BEMF to be off in consists and to cut out at speed step 10 on a 28-speed step setting.
As to the need to change out bulbs, actually the A6X comes with both 12V and 1.5V feeds for functions. Sort of the all-purpose function lighting decoder as well.
It’s very likely true that these boards are different. My two SD7s have the green board. Mine are from the first runs if there is any diffence. Don’t know if there is a circuitry difference, maybe a reason for some of the confusion about decoders. I did have to change the bulbs, fried them in the first install. This was done quite a while ago. Don’t even remember when these first came out, 10-12 years maybe.
Yes, later I saw this on TCS site. So, I sent the mail to this shop, they may have old A6’s on stock, without BEMF. I will try to order newer one.
One more thing: Just today I was testing my only DCC loco for now, Bachmann Spec. 2-8-0. It is factory fitted with a Bachmann decoder. I am aware it is not very good decoder, it will be replaced one day.
So, as I have small L shaped layout, with european track radiuses (min. is about 16,6’), I can notice drop of the speed when 2-8-0 enters the sharp curve. Would the drive with some good BEMF decoder be smoother? Can BEMF make the loco move with apsolutelly constant speed, no matter curves or inclines?
You can think of minimal settings of BEMF turned on to smooth out a loco’s slow speed response so that it keeps running through switches and complex trackwork smoothly, as if the loco has great mass. BEMF is pretty cool for that and can smooth out any loco’s performance in that regard – although if the loco already runs really well at low speeds (like Kato and Atlas units tend to do), BEMF is an extra expense that isn’t all that necessary.
But higher settings of BEMF can make the loco operate like it’s on cruise control – through curves, up hills, down hills – all at the same speed. It’s a cool trick, but it’s not realistic. Real locos need you to work the throttle when you go through curves, up hills or down hills. That’s part of the fun of running trains. Trains on cruise control is just plain booring.
The other thing to watch out for is using BEMF in a consist. Since BEMF wants to keep things running, if you grab and hold the coupler on a loco with BEMF set on you will notice the wheels start turning faster as the loco tries to compensate. If you get two locos in a consist and one starts to lag when the lead loco enters a curve, for instance, the two locos will begin to fight each other, bucking violently.
The rear loco is trying to push to make the front loco speed up to keep the speed constant, and the front loco is trying to slow down to keep the speed constant, and as the loco alternately speed and slow down each other the BEMF compensation tries even harder to fix the speed difference and violent bucking is the result. As a rule, you want to turn BEMF OFF in consists.
You really don’t need BEMF in cons
Hmmm, I thought that “dither” function is in charge of smoothing stiff locos on low speeds! But, I can see what you are trying to explain - cruise control on steep inclines really aren’t so realistic.
Consists are not very important in my modelling world, as I wont have space for more than 10-12 cars per train. And for this, one steamer, SD9 or GP9 is pretty much enough, I think! [swg]
My Proto SD9 already have nice minimum speed, even though it takes 5-6 volts to start moving. I expect to perform even better on DCC.