Dan.
Do you live in Europe? The Power Cab was designed to work off of 120 volts at 60 hertz. Most European countries are 220 volt at 50 hertz. This could be the issue here. I am sure there is some sort of authorized power supply for the Power Cab in your country.
One thing I would try is to take one of the offending decoder/ locomotive combinations to another DCC system and give them a try. This would either confirm or deny a power cab problem.
Pete
Hi Dan,
I’m in the U.K. using a Powercab. The supplied power pack is a 100 - 240V 60Hz unit that’s obviously made for the U.S. market as it has two flat blade prongs. I use a shaver adaptor to plug into the BS standard three pin socket. The voltage is OK but as has been mentioned before, the frequency is wrong for Europe.
That said, I’ve just tried three locos, one Atlas, one P2K and a Kato, all with NCE D13SRP’s and none of them exhibit the sound you can hear.
About four years ago, I did have a Digitrax decoder with their Sound Bug in a Kato loco. Even with the sound muted there was a high pitched faint noise I likened to an electrical whine. This occurred every time power was on, whether that loco was selected or not. I contacted Digitrax who acknowledged the problem but said there was nothing they could (or would) do.
I would be surprised if it was the Powercab, though that seems to be the only constant.
As a last resort have you considered hard-wiring the decoder?
Ian
Logical guess guys, but no I’m in New Jersey (a Brit transplant hence the hornby). I’m trying to think of the easiest way to try them out on a different DCC controller.
Dan
Dan
Maybe a local hobby store or is there a club layout near you?
Some of the U.K. forums have mentioned that some aspects of Hornby are (or at least in the past, were,) not fully NMRA DCC compliant. There were certainly issues with their Select DCC controllers and perhaps this is tied into your problems in some way?
Ian
So the decoder is defective? [%-)]
[:)]
Ok, first things first, Merry Christmas everyone.
I haven’t been able to test anything ona different DCC system yet, but would certainly like to if possible. I find it hard to imagine the decoders are defective, that would be 3 brand new NCE decoders all defective and around 30 Hornby R8249S all defective. Seems unlikely to me.
I did recieve an email notification of a post which I didn’t see appear on the forum thread (maybe removed by the poster?). Anyway it seemed to make most sense to me. The poster implied that perhaps I could hear pulses from the pulse width modulation at 15-16khz. so well within the human audible range, although close to the top end so perhaps not audible to ‘senior’ member of the model railway community (and I saw this with the utmost respect!!).
What does everyone think of this idea?
Dan
Oh, and as far as I know it is only the Hornby select controller that is not NMRA compliant. Some old decoders were not, but all current ones are.
Dan
Try changing the frequency of the PWM - many decoders have this capability - and see if the sound changes or goes away.
Also, the PWM can generate noise in the motor. The motor is actually a more likely source of the PWM sounds than the decoder. For sound to occur, something has to vibrate at an audible frequency. While a loose component is possible on the decoder, the motor is a much more likely source of vibrations.
Older low frequency PWM (and other pulse shapes) were known for inducing motor “growl”, and producing heat in the motor. Which is why most decoders have a variable PWM frequency, often known as “Silent Drive” or similar. At the very least, a fixed pulse frequency is generally moved to 3KHz or higher. Usually, a variable pulse frequency within a range is available to tune the locomotive to the desired qualities.
The down side of higher pulse frequencies is that tie-crawling slow speeds are not quite as good as with a very low frequency pulse (all other factors being equal). But nobody in their right mind operates their locomotives or trains at 1 scale MPH for very long. At 1 scale MPH, it takes a 40ft box car about 30 full seconds to pass a switch stand (in any scale).
Fred W
That post was by me. After posting that I read one of your posts that I missed earlier that seemed to counter what I had posted, so I deleted it (should have just edited it instead, but it was late and I was tired) because I did not what to confuse the situation. Here is the gist of what I posted:
Many of the “high frequency silent drive” decoders have a PWM (pulse width modulation) motor drive in the 15-16 khz range, which is within the range of hearing of many people (and the younger you are, the more likely you are to be able to hear them). I understand the Loksound decoders have a much higher PWM, above 20 khz, so much less likely to be audible.
The thing is, if the PWM drive is the culprit, then the noise should not come from the decoder itself, but from the motor. Reading that the decoders still made the noise even if not connected to the motor is what made me discount this theory
Dan.
Are these plug and pray setups you have? If they are can you unplug the decoders and ohm the pins? I am thinking that there may be some jumpers or traces on the board that needs to be cut maybe? Just this past weekend a club member had a similar problem with an Athearn plug and pray with a Digitrax decoder. He had plugged it into the 8 pin socket and failed to remove the 9 pin jumper from the 9 pin plug that he should have used. Needless to say it buzzed very loud but only for a short time before the decoder popped.
Pete