Attaching dcc power wire to decoder to test

[friscopete]

I want to test a sound decoder without installing it in a loco .Can i just attach a speaker ,motor, lights then attach a lead from controller to black and red leads .As there is no loco or track will this damage a decoder ?

thanks

[John ks]

Friscopete asked "As there is no loco or track will this damage a decoder ? "

Provided you get the wiring correct then it should work fine

Regarding the lights, ensure that they don't overload your decoder

If the lights are LED's the a series resistor ( current limiting) must be used, 1Kohm is a good start

 

If you plan to test more than the occasional decoder than a decoder tester may be worth the investment

John

[Amand]

ESU 53900 decoder tester covers all decoder interfaces for British outline models. Motor, lights and speaker on one circuit board. It’s a pity though that the latest version has a motor that needs very little power to spin very fast. I have the older version with a chunkier motor which I prefer.

 

Other testers are available, e.g. Zimo MXTAP.

[Phil S]

A small caveat:  If a TTS steam loco sound,  then apparently the chuffi g effect will not work because it relies 9n monitoring the motor's bàck emf.

Similarly, the sound of other sound decoders may and slightly different for the same reason ( heavy / light load effects ) but should otherwise work:

As mentioned ...the ESU decoder 5ester is an extremely useful method of testing decoder operation.

The current version has switchable speaker impedance and many types of decoder socket.

[Pete the Elaner]

1 hour ago, Phil S said:

A small caveat:  If a TTS steam loco sound,  then apparently the chuffi g effect will not work because it relies 9n monitoring the motor's bàck emf.

 

 

 

I thought TTS decoders would not synchronise chuffing because they did not do this?

I tried a Zimo steam sound decoder in my MERG tester, which uses a resistor for a load. This refused to chuff because it could not detect impulses from a motor.

 

The load is necessary is to read back CVs. There are some exceptions but most decoders will not respond to read requests without a load where the motor should be.

[Phil S]

Phil: Synchronising, and producing any chuffs at all are not necessarily the same thing 8-)

As I understand from the TTS  - and perhaps the reason people have commented on wrong speeds when fitted to other locos, is that the Hornby team have matched each loco to the Hornby model - knowing whether it was 3 or 5 pole.  How well it changes with speed of the loco is another problem.

ESU and other decoders either track the speed with an algorithm OR can use a synchronising axle-based input, as I understand the options.

In the case of the TTS and steam - it is why, I believe, the '2 decoder solution' does not work - having a silent decoder for the motor and the TTS just for sound ...... whilst it does for a Diesel - and is one of te ways of using a TTS with a 'high power' loco like a Heljan -- the other alternative, which I have used,

is to add a 10ohm resistor in series with the motor to prevent the motor current exceeding 0.5amp... at the cost of a reduced top speed   (which perhaps compensates for Hornby not providing CV5.

 

Although the statement that a resistor load is required to enable readback, is correct:

Readback from a decoder is NOT REQUIRED - it depends on the controller you use.  I use multimauses - and deliberately have one set up with the basic 10764 amplifier so as NOT to have any readback.

(If , extremely rarely - such as bothering to read TTS version CVs because I had lost their packaging and wanted to confirm which  loco tey beloged to - I can plug my multimauses into a MCP or Z21  or dig out a Sprog 2 and s/w ....  But all that readback really does  os slow down the reprogramming process!

[Crosland]

The load is also used to confirm that a write is successful. Without it you are writing blindly and errors do sometimes occur.

[RedgateModels]

Just to back up what has just been said, Zimo sound decoders need a motor connected to read CVs. I recently did a sound fit on a Hornby 28xx and despite testing out the decoder on my ESU tester before fitting - the darn thing would not run or read on the programming track. Turned out the two wires from the DCC socket to the suppression capacitor under the speaker (this was significant) had not been soldered and were only just holding on via the heatshrink. When I disturbed the wiring fitting the speaker the motor became disconnected and hey presto no movement and no reading of CVs!

[pauliebanger]

6 hours ago, Pete the Elaner said:

I thought TTS decoders would not synchronise chuffing because they did not do this?

I tried a Zimo steam sound decoder in my MERG tester, which uses a resistor for a load. This refused to chuff because it could not detect impulses from a motor.

 

The load is necessary is to read back CVs. There are some exceptions but most decoders will not respond to read requests without a load where the motor should be.

 

That's correct. TTS steam decoders do not work in the same way as other sound decoders. Hornby may indeed tune them to specific models, but they are still not synchronised.

 

It is impossible to get them synchronised except in the same way that a broken clock is correct twice a day i.e there will be sweet spots, but there is no way to adjust the chuff rate relative to the road speed/wheel revolutions.

 

If you remove BEMF regulation by setting CV58 = 0, steam projects in ZIMO sound decoders will chuff and change rate according to throttle position. (Others probably do so too).

 

Best regards,

 

Paul