Hornby class 87 and 36-553 decoder cv's

[Dan Griffin]

Hi, i have fitted a Bachmann 36-553 decoder to a Hornby 87. i have adjusted the back emf cv's 54 and 55, but its still a bit jerky. has anyone else done this and what values they entered to make it run nice and smooth? thanks.

[HLT 0109]

Dan,

 

I do not know what procedure you have followed in choosing your settings for CVs 54 and 55 and I appreciate that the extract copied below is not from any instruction manual for the 36-553 decoder, but it may help you.  The instructions are in fact from the Loksound v3.5 manual but it might be worth trying.  Before making adjustments, it would be well to make a note of the existing values in case you end up with worse running (although you could then reset by putting value 8 into CV8).

 

"Reference voltage:

In CV 53 you set the voltage that should come back

from the motor.

This value depends on the track voltage and the

coefficient of utilization of the motor. A coefficient

of 75 % and a track voltage of 16 Volts adds up to

a voltage of 16 V * 75 % = 12 Volts. This value has

to be written into CV 56. The voltage (here: 12 V)

may be entered in 0.25V-increments. This results in

a value of 30 (12 V * 2.5) for CV 53. If you don’t know

the exact motor coefficient, you may obtain the

value experimentally as follows:

Check if the engine really reaches top speed at the

highest speed step or if you cannot detect any speed

changes at the maximum speed step. In the latter

case you have to reduce the value for CV 56, in the

first case increase the value. The internal PI regulation

of LokSound can be adjusted with CV 54 and CV 55.

Depending on the type of motor the parameters may

have to be adjusted to achieve optimal running

performance.

LokSound decoders are factory pre-set for the use

with ROCO®-, Brawa®- or Kato motors.

Parameter „K“, stored in CV 54, influences how

strongly load control will effect the driving

performance. The higher the value, the more load

control will respond to any changes. Adjust this value

with care, because too high values could lead to

irregular and „hard“ driving performance. If you

prefer smooth running, try to reduce the value step

by step until you reach an optimum.

Parameter „I“, stored in CV 55 provides important

information to the LokSound decoder regarding the

motor type used: certain electric motors respond

differently to adjustments of the rpm’s. The longer a

motor takes to respond, the lower the value in CV 55.

However, it is not easy to recognize the degree of

inertia. In general: the more poles a motor has and

the bigger it is, the more fly wheels it has, the slower

it is and the lower the value should be set in CV 55.

For optimal programming proceed as follows:

Read out the value in CV 53 as described above. Leave

the value of CV 55 (parameter I .I.) for the time being

and test the engine. Now change the value of CV 54

in steps of 5 downwards or upwards and monitor the

running properties of the engine. If there is no

improvement leave the value of CV 54 and change

the value of CV 55 (intensity of control) in steps of 5

until an optimum is reached."

 

The instructions can seem rather confusing and it may be that you should ignore those given for CV53.  There appears to be an unfortunate reference to "CV53" (underlined in the extract) which I think should say "CV54".  Incidentally, the default settings for the Loksoound are : CV53 =56; CV54 = 32; CV 55 = 24.  Are these anything like the original settings in your decoder?

 

Someone else may have a simpler solution but I hope this is useful.

 

Harold.