High pitched noise from DCC fitted Hornby Black 5

[preecev]

A recently purchased R2382 Black 5 ran OK after fitting DCC decoder for a while, then started to make a whining noise and not move. Took body of and noticed that the decoder was starting to get hot. Took decoder off and put blank plug back in and tried it on DC. Ran OK and very smothly. Tried the decoder in another brand new loco and it worked OK. So then put a new decoder in the Black 5 and got the same whining noise with no movement again. Has any one had simliar issues and possible cause.

[96RAF]

When the blank is fitted it only shorts between pins 1-8 and 4-5. When the decoder is in it can pickup a short between these pins and the four inner pins. Closely inspect the socket for solder tracking. You may likely have to unscrew it for access to the underside. If you have a meter check for shorting between any of the above pins.

[ColinB]

The only time I have had that was surprisingly in the new Rails class 812 with factory fitted sound. It worked out that the 18 pin dcc header wasn't in properly, but the black 5 has a normal 8 pin DCC socket so it is not that. It sounds to me like there is a short on the DCC connector but not on the usual pins otherwise the decoder would blow up. You need to check resistance between adjacent pins, the only one you should get a reading on is between pins 1 and 5. Then if you find a short take the dcc socket off and inspect the underside as 96RAF suggests. Of course it could be that TTS decoder just doesn't like the motor in the black 5, that is a possibility. On my Duchess of Gloucester it never would work with a TTS decoder properly (I tried about 3), losing sound. In the end I paid out on a Zimo Sound decoder and now it works perfectly

[96RAF]

The OP never said he had tried a TTS decoder Colin, in fact he never mentioned any make or model of decoder.

[ColinB]

Sorry 96RAF assumed whining noise was from TTS. In that case I haven't got a clue. All the test are still relevant.

[Jupiter 1707822591]

I have the same model (sound fitted) It makes the same noise .Found no detriment to its function .

[96RAF]

In that case it sounds like it could be feedback in the motor from the PWM frequency. You can make a motor do this when using HM6000 analogue app controller by winding the frequency up. Possibly nothing can be done about it unless you can find a decoder that suits the motor better.

[preecev]

Thanks for replies. I should of mentioned that I have fitted a Hornby decoder R8249.

[96RAF]

There is nothing you can change on an R8249 that will help unfortunately.

[Dave Horn 69]

I have a similar problem with a Hornby R2994XS, 7029 Clun Castle, with factory-fitted "proper", as opposed to TTS, DCC sound. The locomotive moves but the sound unit only makes strange electronic sounds, no steam locomotive sounds. The only suggestion that I have had is to fit a new sound chip.

[Jupiter 1707822591]

Have you tried to reset the decoder.?

[Dave Horn 69]

@Jupiter

Unfortunately I'm unable to, as I only have DC control, with associated limited sound capability, not DCC, though I do have a Bachmann DCC set-up in my unopened Western Pullman (reverse blue and grey livery) set.

[96RAF]

Just because a loco runs well on DC with a blanking plate doesn’t mean all is well for DCC operation, although it should be.

Given the fault is there with more than one decoder I would suggest the decoder socket is either wired incorrectly or there is solder tracking or a stray wire strand bridging between the traces feeding the socket pins. Lift the socket and closely examine for cross connection between the pins. Check with a meter if you have one.