R1255m and 8TXS bluetooth disconnects

[Baz1205]

I have just installed an HM7000-8TXS Bluetooth & DCC Sound Decoder (8-pin) into my oo gauge R1255M Flying Scotsman. It's pretty tight but I managed to get everything in and nothing is shorting. I purchased a P9100 UK Digital Transformer 15 V 1 A and connected it to piece of test track, installed the software on my iPad Pro (M1) and set up the decoder. Updates installed along with a new sound profile and all the sounds worked perfectly. However when I tried to move the engine it made all the right sounds and the wheels moved slightly (like 2 mm) then everything stopped. No movement, no sound and bluetooth disconnected immediately. A few seconds later bluetooth reconnected and it started playing sounds as if it was going to start moving but nothing happens. I have reset the engine on the track and reseated the decoder and even tried splaying the pins slightly to ensure they are all making contact but it simply will not move. I checked the engine by putting the blanking plate back in and connecting the original controller and it works fine. I'm not sure what to try next as whatever I try, it always does the same thing.

[96RAF]

It is presumed you updated the sound profile to the latest version and that you have carried out all the steps in the troubleshooting guide listed in the sticky post at top of the index page.

[Baz1205]

It is presumed you updated the sound profile to the latest version and that you have carried out all the steps in the troubleshooting guide listed in the sticky post at top of the index page.

 

 

As stated I updated the sound profile and additionally reset the whole system and reinstalled it from scratch. I followed the troubleshooting guide before posting here to no avail.

[96RAF]

Contact Customer Services by phone although I don’t know how much cover they will be providing over the holidays.

[SteveM6]

While waiting for customer services, check and clean track, wheels and pickups.

Do you have any other locos on track or anything else powered from that PSU as 1 amp can easily be overloaded and trip?

[Baz1205]

While waiting for customer services, check and clean track, wheels and pickups.

Do you have any other locos on track or anything else powered from that PSU as 1 amp can easily be overloaded and trip?

 

 

Thanks I’ve cleaned the track and loco but it still behaves the same. Using the analog controller on the same track with the decoder removed and blanking plate installed the engine works the full length. I’m just using a short length of single track with no other locos on it. It’s got me stumped this one.

[Baz1205]

Contact Customer Services by phone although I don’t know how much cover they will be providing over the holidays.

 

 

Yes if I can’t troubleshoot it I’ll contact them after the holidays. I feel I’m so close…. Thanks for your suggestion.

[Rallymatt]

Steve M6 is hinting at this, as soon as the motor starts spinning up the decoder cuts out, that sounds like the current draw from the loco is over the limit of the decoder, 1amp. If you have a multi-meter it would be worth checking.

[96RAF]

It would be interesting if it could be tried on DCC track power and also if responsive under DCC control. I appreciate you likely do not have access to DCC kit.

[Baz1205]

Frstly thank you all for your replies. They have given me a lot to think about. I’ve been doing a bit of digging at I suspect the 1A transformer isn’t up to the job. Once connection is made I can activate any of the sound effects and sit here all day (if so inclined) and the loco remains connected. But as soon as I try and move her it disconnects. So to me it appears the loco requires more power. I don’t have access to and other DCC kit so sadly I can’t test it that way. I’ve ordered the 15v 4a psu which should be here by Wednesday. Fingers crossed this will provide the solution I require. I’ll keep you advised.

Have a very Merry Christmas and have fun.

[96RAF]

Try to move it with the sound off, then once moving hit the sound.

[Baz1205]

Try to move it with the sound off, then once moving hit the sound.

 

 

I tried that but to freeze’s instantly when I do. I do think it’s the draw of the motor that is pulling the psu down.

[Brew Man]

It definitely sounds like an over current issue to me.

[Pendragon Sailing]

It would be helpful to know what current the loco’s motor is drawing. Are you able to undertake a Stall Test on the loco (under analogue control)?

It does sound to me that the either the track power (at 1A) is insufficient and/or the decoder isn’t able to manage the current draw of both motion and sound at the same time.

[ColinB]

The loco is from a modern Hornby set so unless the motor is seriously faulty I suspect something is wrong with the decoder. So the first thing to do is remove the HM7000 and test the loco on DC. From my experience these locos are one of the more reliable so do the test and check it works perfectly on DC. If the loco runs ok on DC then I suspect there is something wrong with your HM7000. The maximum current for the motors in these locos is less than 500 milliamp (1/2 Amp) as if they were greater all the old Hornby decoders would fail (they will only source 1/2 Amp). The other thing to do is switch off the sound if you can do that on Bluetooth, and see if it runs.

I forgot to add I had a HM7000 work with a rubbish power supply supplied with a Pendolino set, ok the sound was distorted but it had enough power to run a West Country loco, so your power supply should be more than sufficient.

[Froobyone]

I had the same problem with my TXS fitted TT:120 shunter.

Firstly, I turned the volume down to around 8%. Then I cleaned the wheels with some isopropyl alcohol. I then cleaned the track with some wood. It started to run better, but still not 100%. So I then checked every contact wiper on the wheels and adjusted them.

This improved things immensely. However it will still occasionally stall on normal track, for no readily apparent reason. Fitting a stay alive will solve all of my problems, but getting one in there...

The main issue is that once it loses connection for a second, the Bluetooth drops and has to re-acquire. I'm hoping switching to an Elite controller in the future means that any drops won't matter as much.

Hope this helps.

Good luck

[Britannia Builder]

I know that you said that you'd splayed the decoder pins slightly to ensure good contact, but poor contact here still seems to me the most likely cause of the problem. A high resistance here would drop the voltage to the decoder when the motor tries to draw current. This issue has been mentioned several times before, and someone said that it took several attempts to get good contact. The four corner pins are the ones that carry the current.

A genuine overcurrent from a faulty motor would activate the safety mechanism to cut the motor power, but still leave bluetooth and sound active.

Regards, John

[ColinB]

Oops, reread your initial post and you have checked it on DC, so it has to be the decoder or the decoder pins.

[ColinB]

Oops, reread your initial post and you have checked it on DC, so it has to be the decoder or the decoder pins.

[96RAF]

There is a definite problem with the tolerances of the NEM652 connector. A typical plug and socket is poorly engineered when a decent header socket/pin system could be applied which would resolve all these need for splayed pins and slack fit or over-length pin problems.

[Baz1205]

I hope you’re all having a great Christmas. Mine was going great until today. I tucked my Flying Scotsman away over Christmas awaiting my Hornby 15v 4a power supply. It arrived today so with bated breath I set her up again and reinstalled the decoder. Same problem, she moves a couple of millimetres then stops and the decoder disconnects. Bluetooth also fails so it’s a total recycle of the connection taking place. With the new PSU it does reconnect almost instantly and the loco tries to move but no, it just keeps disconnecting and the recycle is endless. Sound on, sound off, makes no difference either.

I cleaned the wheels with some isopropyl alcohol then cleaned the track but this didn’t help. The NEM652 does seem to be the Achilles heel here. I have gently moved the pins multiple times to try and get the best possible contact and some attempts did genuinely appear to yield better results but we’re talking just a few more millimetres here and this could have been caused by other factors, or maybe it just wishful thinking. I rang Hornby’s support but they had all gone home so I’ll try again tomorrow. I do wish there was a better solution that the 8 pin socket. It seems so antiquated nowadays.

[Daedalus]

Have you tried running it with the body off?

[Baz1205]

Have you tried running it with the body off?

Yes I have. I’ve only had the body on once in all my tests.

 

 

[Daedalus]

Running in reverse? Turning the loco round so you will be using the other "half" of the bridge rectifier?

[Baz1205]

Running in reverse? Turning the loco round so you will be using the other "half" of the bridge rectifier?

Yes tried that. Same result.