Review and DCC upgrade of a PIKO BR 94 #37250

[idlemarvel]

The BR 94 is a recent addition to the PIKO G scale product line. It was released in 2022. There are two versions available, one analog DC #37250 and the other fitted with DCC and sound #37251. Both these are DR versions. Another version has been announced #37252 in DB livery, also fitted with DCC and sound. This thread is mainly about dismantling and digitizing the analog version #37250. The manufacturer details are below:

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It is quite a detailed, impressive and imposing model. The analog DC version has directional lights, cab light, flickering firebox, wheel/motion lighting and a standard smoke generator. The DCC version also has sound with two triggered by reed switches under the loco. The two reed switches have no function on the analog version but they are fitted nevertheless. Here is the model compared to a prototype:



You might be saying "how come there are no rivets on the side tanks" but riveted tanks were replaced with welded tanks due to excessive leakage. If you're interested in this and the many other design variations of this loco, this site has you covered:

Die Bundesbahnzeit - Baureihe 94.5

bundesbahnzeit.de

First question is why not buy the factory installed DCC version? I did consider this but all my other locos have Massoth XL and Massoth sound modules, and I already had a spare XL. One downside to this is that currently there is no Massoth sound project for a BR 94. I am sure the PIKO decoder is perfectly adequate and if you go down this road you can skip the rest of this thread, which is quite long and involves quite a bit of work. If you wanted to "batterify" this you would also have to dismantle the loco.

Anyway to business. First thing it to take a look underneath. As you can see the 0-10-0T is articulated into a 4 wheel motor block at the rear and a 6 wheel motor block at the front. The cylinders are attached to the 6 wheel motor block and the main crank drives the third wheel as on the prototype. Unlike some other PIKO 6 wheel motor blocks it is not itself articulated and has quite a long wheelbase.



This is probably why the PIKO documentation says although this model will run on R1 600 mm radius curves it is recommended to run on larger radius (PIKO R3 or bigger). I haven't found it much of a problem but it does slow down a bit on entering R1 curves.



It doesn't look too bad from the side, but an aeriel view (grotty photo) shows why it might struggle.



Note the wheel pickups are spring loaded "bullets" not brass strip wipers, plus each motor block has a pair of skates. I have removed the skates in later pictures as I feel 10 wheel pickups are probably enough.



Whilst we're underneath, the bulge on the rear motor block houses the two reed switches which can be used to trigger sounds.



CONTINUED IN PART TWO

 

[idlemarvel]

PART TWO

The instructions for dismantling the loco show 7 screws but it is far from simple getting to them and removing the body.

Note that it is not necessary to dismantle the body just to install a motor and light decoder, but if you want to install sound and specifically a speaker you do.

The first pair of screws are about half way along the body.



The second pair are concealed inside the box used to house the analog circuit board. To get to that you have to remove the rear coupling structure with the air cylinders.



Be careful removing this as there is a spring, a toothed washer and a spring clip as part of the structure. Once that is removed you have to remove the lid of the box (2 small screws) and lift up the circuit board to get to the two larger screws.



The third screw is inside the boiler. To get to this open the boiler door and slide out the circuit board.



This contains the circuits for the front lights and smoke generator.



To get to the screw you need to lift the smoke generator out of the chimney.



Finally you can get to the screw.



Now it is possible to remove the bodywork. Start with the cab. The difficulty here is the number of individually moulded control rods that have to be disconnected. The control rods - there are seven in total - are quite delicate and one in particular refused to be removed from the body and I ended up snapping it.



The last screws are revealed when the side tanks are removed (already unscrewed in the first step).
Here are the screws.



With the cab removed some electronics are revealed that are hidden in the coal bunker. In the middle is the circuit board wiring for the rear, motion and firebox lights, and the smoke generator.



To the left is an insulated packet containing the motor electrical suppressors.



Note the cab has a lead to it from the boiler which is for the cab light and top rear light. You can unplug this lead from the cab if you want to give yourself a bit more manoevering room.



Once the cab has been removed you can remove the boiler. The superheater on the side of the boiler has to be removed as it is attached to both the boiler and chassis.



With the boiler removed you can get to the speaker enclosure. In front of that is another circuit board for the firebox lighting. The speaker enclosure has a small slot in one side to allow for the speaker cable. To the left is a space where the sound module will go.



CONTINUED IN PART THREE

 

[idlemarvel]

PART THREE

Now that all the wiring is revealed, time to draw a circuit diagram of the existing wiring before I start meddling. It is quite complicated with wires interlinking nine separate circuit boards.



Ready to start the DCC and sound upgrade. This will involve installing a speaker, a sound module (Massoth S) and replacing the analog DC board with a Massoth XL decoder. The plan is to retain all the existing wiring for the lights and smoke generator.

Remove the speaker enclosure and fit the speaker. A 50 mm 8 ohm Visaton FRS 5 is the recommended speaker. Refit the speaker enclosure. Connect the speaker cable to the sound module.



Turn the loco over and open the decoder hatch.



Remove the analog DC board. Detach the speaker lead, which leads to the external volume control. You could make use of in this retrofit, but the volume controls and light switch controls are so hard to access it hardly seems worth it.



Note that the wires from the reed switches are soldered to the board and need snipping off. I haven't used these switches in my upgrade but if you did want to you would have to solder these to the appropriate contacts on the Massoth S. All the other leads are screw fit.



Now we can replace this with the Massoth XL.



This is how the various wires are connected.

This would be very similar for a Massoth XLS (motor, lights and sound decoder). The Massoth S can be connected to the Massoth XL by a SUSI cable, but there are a few steam sound related settings that are not available in SUSI mode, so I connected the power leads of the Massoth S to the Massoth XL track power connections.

I won't go into CV settings for the motor, lights and sound, except to say that the lights and smoke generator voltages need to be reduced from full track voltage to 5 V or thereabouts.

That's about it. Just the small matter of reassembling. As mentioned earlier the hardest part is refitting all those plastic control rods without breaking them. I think if I was starting this again I would have shelled out the extra money for the factory installed version, but where's the fun in that?