Split Chassis?

[Wear Valley Wanderer]

Hi All,

 

I have an old Fleischmann BR95 which I bought second hand on ebay ages ago. It was sold as DC which it works on just fine, but to my surprise I discovered it had a DCC decoder hard wired into it! Unfortunately the chip appears to be dead. 

 

I'd like to sound fit this for DCC operation, but the chap who sells the chips thinks it may be a split chassis and was concerned it may damage the chip. As I'm not an expert by any stretch of the imagination I'm not sure if it is or not. I already own a split chassis loco, but it looks nothing like this inside. I've attached a couple of pics. Any thoughts? 

 

Cheers,

 

Mark

 

[Hamburger]

Hi Mark,

 

it is not a split chassis but a live chassis means the whole chassis is electrically connected to one side of the track.

Having any parts (Seuthe smoke generator or lighting) connected to the chassis might cause problems.

The motor contacts always MUST be insulated from the chassis.

 

[Wear Valley Wanderer]

I've never heard of Live Chassis before. I looked them up and, sure enough, it is one. All the wipers are on one side like you said, although it's interesting to see how they've wired in the old decoder.

 

I have a smoke generator and lights which are connected to the chassis and then the white wire on the decoder, which as you said could cause a bit of a headache. I've bought a cheap decoder to replace the old one, so if it blows I won't be too out of pocket! Every day is a school day.

 

Wish me luck 

[Salmotrutta]

Live chassis was the most common way to pick up in the DC days- at least all the Triang, Hornby and Wrenn stuff did. I have also a number of BEMO Swiss outline locos that do as well. Not a lot more difficult than installing in a isolated chassis as long as you can isolate the motor entirely and watch out for short circuits against the chassis. 

 

Surprised it ran on DC if the chip is dead. The blue wire on that chip is not usually used with a live chassis install, it's usually supplying the (+) to lights and other functions in an isolated install. Maybe that's floating around and causing problems?

Might be worth taking that chip off and seeing if it works on DCC when not on the loco, or re-setting by writing to CV8. Look it up on the LENZ website to see what you have to write into CV8.

 

Smoke units take a fair bit of current so I would be surprised if it worked off the white wire which is for a bulb! Are you sure it is going to the smoke unit and not to the front light? Some installs use a small relay from one of the AUX outputs of the decoder to fire up the smoke unit from track power - which also has the advantage that the smoke can be synchronised by programming the chip. 

[Nigelcliffe]

23 hours ago, Wear Valley Wanderer said:

I've never heard of Live Chassis before. I looked them up and, sure enough, it is one. All the wipers are on one side like you said, although it's interesting to see how they've wired in the old decoder.

 

I have a smoke generator and lights which are connected to the chassis and then the white wire on the decoder, which as you said could cause a bit of a headache. I've bought a cheap decoder to replace the old one, so if it blows I won't be too out of pocket! Every day is a school day.

 

 

It is perfectly acceptable to wire one side of lights or smoke generators to the pickups.   It is documented in any decent decoder maker's manuals, and is the wiring arrangement in a 6-pin decoder.    The available power to the lights (or smoke unit) is then half-wave, and approximately half of that which would arrive via the blue wire.     

 

Some smoke units are designed to run from the current available from a decoder's output.  Check both the smoke unit specification, and the decoder's rated output on the function wires.   If correct specification of smoke unit and decoder, then it is wired correctly. 

 

You must not use both blue wire AND pickups to the same light (or other device): that will end in damage. 

 

From the evidence presented so far, I can't see any fundamental issues with the original installation.  That it fails to run on DCC, yet runs on DC, suggests a decoder CV setting issue - has the address been changed (perhaps by random event), is it stuck in a consist (CV19 not zero),  etc..  

 

 

 

 

- Nigel

 

[Wear Valley Wanderer]

An update:

 

Shortly before I started setting up for DCC I bought a plug in Seuthe smoke generator for this loco which worked pretty well. The loco was designed for a specific type and it just drops into place without the need for additional wiring. The body of the holder, if you think of this as the negative, is isolated from the positive which doubles as the positive for the bulb at the front of the loco. The bulb slides into in a channel in the smoke gen housing. You can see this in the top photo. 

 

When I recently placed the loco on my programming track, the lights came on immediately as well as the smoke generator which I believe is suggestive of a short. There was no sign of life from the chip. What I did find however is that the white wire from the decoder to the back of the bulb has melted and detached.

 

The smoke gen is : Seuthe Nr.9 Plugin Steam Generator 9-14 Volt.

 

It may sound obvious, but I'm wondering if the heat from the smoke gen is causing some of the problem and I would be best going for an LED solution. The blue wire too, as noted above by Salmotrutta, is just flapping around with no purpose and no insulation. A lot to think about and to look at as I go forward. I know it's an old girl, but it's a challenge that is not only strangely involving, but dare I say enjoyable and frustrating in equal measure!

 

 

[Nigelcliffe]

The Seuthe website says a No.9 pulls 140mA of current.

 

Decoder, don't know.  The number on it identifies the processor as fairly ancient, but not sure which Lenz decoder model number it matches.   Assuming its the equivalent of an old "Silver" (which is quite an assumption), then the function output is 100mA, so not adequate for the smoke unit.  But need an accurate decoder identification to get a firm view on this.

 

No idea why your programming track does what you report.  But different systems power or don't power the programming track in slightly different ways. 

 

[Wear Valley Wanderer]

Having some irritating issues with this thing. First of all, in the absence of the original box, I found out that it's made by Lilliput, not Fleischmann.

 

I've installed a Train-O-Matic Lokommander 2 Mini NEM 652 (9 wires + 8 pins) (W8P).

 

This is the first time I've ever hard-wired a loco, and I'm very happy to say it runs nicely in both directions and I can even control the smoke (Function 4).

 

Unfortunately the directional lights aren't working at all. They're both 3v LEDs which I installed to replace the original incandescent ones. Front one is connected to the white wire and the rear to the yellow. A 1k Ohm resistor is connected to each (On the positive legs) with the negative of each leg joining the same blue wire (common ground) to the chip. The ground from the smoke gen also joins these two. I've had a look at the online manual for the chip, but it's absolutely baffling to a beginner like me. I have a Z21 controller, and have set F0 as lights, but nothing happening here. 

 

I have tested the lights with a 3v source and they work fine, and all the wiring seems good.

 

Any thoughts?

 

 

[smokebox]

The blue wire is positive, not negative.

[Wear Valley Wanderer]

13 hours ago, smokebox said:

The blue wire is positive, not negative.

 

Good grief. I've watched countless videos on fitting DCC, LED's and goodness knows what else, and somehow I completely missed that. I've since re-soldered the lot and it all works. The smoke generator is a bit of a weird one though as it makes a hell of screeching noise and pops like crazy. Not much in the way of smoke either. Still, it all runs nicely so I'm very happy about that.

 

Thanks for the pointer.