point decoder problem

[geoffb41]

Just installed 6 point decoders (the couple i checked were 8216) and powered them from the power leads to the rails and not from the rails themselves.had a few probs programming them but all seem to be setup now.

The problem is mostly when i select

one on the elite to change it get a noise but it doesnt actually move.Seems like if i leave it a few secs after this and try again it will work ok and seems to work ok from then on. Its as if it doesn't have enough power if u try to change it quickly after

selecting one.

Going to be hard to control things if the points don't change reliably Apprecitae any advice

geoff

[Flashbang]

Hi
The point decoders have internal capacitor discharge units (CDUs). These need to recharge once the CDU has operated a point motor. The time taken to recharge will depend on the power available from the DCC system.

A Select using the 1.0Amp

Power Supply Unit may if there are several locos running take a few seconds to accomplish a full recharge. Where a Elite with the (4.0AMP PSU) giving 3.0Amps to track might only take a second to reach fully recharged.

Allowing a few seconds to elapse

between operations will help. If you have the Select with the 1.0Amp PSU consider upgrading to the 4.0 PSU C7024.

[Gregd99]

Flashbang,
I would have thought that the CDU recharge time would be set by current limiting inside the decoder rather than the capacity of the power supply outside teh decoder.

This limiting would be set to work with the lowest common denominator

power supply. Eg the Select can supply 1A... let's limit the current pulled by the decoder to 100mA. This would mean that even if 2 or 3 points were operated at the same time that there would still be 70% of the power available for locos.

I don't use

the hornby decoders but this is what I would imagine.

Do you see it the same way?

[ace10086]

I did have a look at one of these decoders in the past. I seem to remember, given the capacitors and resistors in use, that there is about 2 to 3 seconds needed to completely charge the CDU from 0v to 15v so you are right this is where the current limit

exists, not the 1A of the select controller. Anyway you state you are using an Elite.

Two things to check are a good connection to the power source, if you are connected to a remote part of the track then you could have a voltage drop under load which

will affect things. Also the alignment of the points motors. If the points are not free to move easily then the motors will consume more power trying to move the points which in turn will increase the recycle time of the CDU.

Are you using Hornby points

motors?

I do notice that the first time I try to switch a point after the track has been powered up it doesn't work well, it is almost as if the CDU doesn't charge up until the decoder has been used - this may be just on my 8216 though, need to check

on the 8247s.

If I wait around 1 second between switches then I don't have any problems with failed switch overs.

[geoffb41]

ace10086 said:

I did have a look at one of these decoders in the past. I seem to remember, given the capacitors and resistors in use, that there is about 2 to 3 seconds needed to completely charge the CDU from 0v to 15v so you are right this

is where the current limit exists, not the 1A of the select controller. Anyway you state you are using an Elite.

Two things to check are a good connection to the power source, if you are connected to a remote part of the track then you could have a

voltage drop under load which will affect things. Also the alignment of the points motors. If the points are not free to move easily then the motors will consume more power trying to move the points which in turn will increase the recycle time of the CDU.

Are

you using Hornby points motors?

I do notice that the first time I try to switch a point after the track has been powered up it doesn't work well, it is almost as if the CDU doesn't charge up until the decoder has been used - this may be just on my 8216

though, need to check on the 8247s.

If I wait around 1 second between switches then I don't have any problems with failed switch overs.

[geoffb41]

Thanks for your advice.The point motors are peco.Don't think its a wiring problem as its still doing the same when i wire the elite directly to the decoder and the motors move pretty freely.

Its just the points won't reliably change the first time

you select them espesically if you try and do it quickly. Usually just gives a click.Wait a few seconds and they will work fine from then on.
So its as if there's not enough power there to move them the first time and then they ok
Just finished all the

wiring so i'll see how it goes.

geoff

[daveboy]

ace10086 said:

I did have a look at one of these decoders in the past. I seem to remember, given the capacitors and resistors in use, that there is about 2 to 3 seconds needed to completely charge the CDU from 0v to 15v so you are right this

is where the current limit exists, not the 1A of the select controller. Anyway you state you are using an Elite.

Two things to check are a good connection to the power source, if you are connected to a remote part of the track then you could have a

voltage drop under load which will affect things. Also the alignment of the points motors. If the points are not free to move easily then the motors will consume more power trying to move the points which in turn will increase the recycle time of the CDU.

Are

you using Hornby points motors?

I do notice that the first time I try to switch a point after the track has been powered up it doesn't work well, it is almost as if the CDU doesn't charge up until the decoder has been used - this may be just on my 8216

though, need to check on the 8247s.

If I wait around 1 second between switches then I don't have any problems with failed switch overs.

[daveboy]

ace10086 said:

I did have a look at one of these decoders in the past. I seem to remember, given the capacitors and resistors in use, that there is about 2 to 3 seconds needed to completely charge the CDU from 0v to 15v so you are right this

is where the current limit exists, not the 1A of the select controller. Anyway you state you are using an Elite.

Two things to check are a good connection to the power source, if you are connected to a remote part of the track then you could have a

voltage drop under load which will affect things. Also the alignment of the points motors. If the points are not free to move easily then the motors will consume more power trying to move the points which in turn will increase the recycle time of the CDU.

Are

you using Hornby points motors?

I do notice that the first time I try to switch a point after the track has been powered up it doesn't work well, it is almost as if the CDU doesn't charge up until the decoder has been used - this may be just on my 8216

though, need to check on the 8247s.

If I wait around 1 second between switches then I don't have any problems with failed switch overs.

[daveboy]

I too am having a problem with 1 point connected to port 3, which refuses to work after the first first time using Hornby point decoder. It works perfectly with a HD CDU every time. What size is the capacitor in the Hornby Decoder and could the capacitor

be upgraded?

[stevecamden]

Which point decoder are you using? I can assure that the R8247 will throw two points at the same time easily and recharge in a second. I don't have any experience of the 8216.

[SailorSam]

Hi all, whilst reading and understanding the issues here re the different outputs of the Select and Elite units for operating the two types of point decoders. Would the R8216 work any better on an Elite if it was powered from a booster and not the track.

[stevecamden]

No - The Elite is more than adequate for even medium to large layouts.
Steve