newbie issues with Peco CDU

[WhyD]

HI all

 

My son and I are building our very first model railway layout, so apologies if somewhat basic. 

 

I've installed the first point motor (seep PM-1) and when I'm testing it directly from the Horny Select's AUX output (16v DC, IIUC) it switches ok. 

I've noticed the select screen flickering when I did that and quick research revealed the need for a CDU

 

I went to the local shop intending to buy a Guagemaster CDU, but ended up leaving with a PECO PL-35, only because its enclosed and as our layout is in a shed it seemed a good idea. 

 

Anyway - whilst the point switches well when I (manually, for the test purposes) tap the wires directly, when I do the same with the CDU in between, in doesn't seem as powerful, and in one of the direction does not travel fully and I have to keep tapping to get it switched all the way

Once I remove the CDU, changing nothing else, the point works again, so I suspect it is CDU induced. 

Thinking it might be charge time, I made sure I waited (quite) a few seconds between directions.

 

As I mentioned, when using the CDU the input comes from the Horby select's 16v DC AUX output (yes, I've learnt I'll need an independent power supply, but at this point nothing else is using the select

 

What am I missing? 

[kevinlms]

HI all

 

My son and I are building our very first model railway layout, so apologies if somewhat basic. 

 

I've installed the first point motor (seep PM-1) and when I'm testing it directly from the Horny Select's AUX output (16v DC, IIUC) it switches ok. 

I've noticed the select screen flickering when I did that and quick research revealed the need for a CDU

 

I went to the local shop intending to buy a Guagemaster CDU, but ended up leaving with a PECO PL-35, only because its enclosed and as our layout is in a shed it seemed a good idea. 

 

Anyway - whilst the point switches well when I (manually, for the test purposes) tap the wires directly, when I do the same with the CDU in between, in doesn't seem as powerful, and in one of the direction does not travel fully and I have to keep tapping to get it switched all the way

Once I remove the CDU, changing nothing else, the point works again, so I suspect it is CDU induced. 

Thinking it might be charge time, I made sure I waited (quite) a few seconds between directions.

 

As I mentioned, when using the CDU the input comes from the Horby select's 16v DC AUX output (yes, I've learnt I'll need an independent power supply, but at this point nothing else is using the select

 

What am I missing? 

This

 

<As I mentioned, when using the CDU the input comes from the Hornby select's 16v DC AUX output>

 

As the input voltage is D.C. the diodes in the CDU will actually REDUCE to voltage available at the output of the CDU - the last thing you want.

What you want is a plug pack transformer, rated at around 18 volts AC. That would give an output voltage of about 1.4 times or 23-24 volts DC.

 

Your point motors will then work fine & the one plug pack would work for multiple CDU's (if needed on a larger layout).

[Junctionmad]

The PECO Cdu is rated for 16vac max

[kevinlms]

The PECO Cdu is rated for 16vac max

What is the rating of the capacitor?

[DCB]

How are you operating the points with the CDU in circuit?    Some passing contact switches first kick the point blades in the wrong direction before applying power in the correct direction, this works well with no CDU.  As soon as you add a CDU the point motor fires the wrong way, discharges the Capacitor and there is little charge left to actually change the point.    I use two way switches as sold for signals rather than points to select the direction and a push button to energise for simple CDU systems.

For more complex systems I use an electric pencil or rotary switch with push button and diode based route setting.

Don't overcharge capacitors they go bang and shoot out vile smelling yellow liquid if you do.

[RAF96]

Ref the Hornby passing contact switch this is one that doesnt work well with a CDU. See Brian Lamberts (Flashbang) site for more info about why this is and how to avoid it.

Rob