George-351466 Posted April 2 Share Posted April 2 I’m returning to an issue previously referred to in passing, but now really bugging me. What is the reason why HM7000 chips cut-out when fitted to older locos? Yesterday I made a concerted effort to get my (quite new and little used) J83 to run with a Bluetooth chip. It’s connected via a fitted plug-in socket, so no hot wiring. It runs fine in analogue (with blanking plug) and linking via iPhone is no problem. All is fine on screen and sounds are all there, but……when movement is attempted there’s an initial twitch, then the loco freezes and the link is lost shortly after. It will not re-connect to the phone unless the transformer is switched off and the app closed then re-started. I’m having the same issue with a cd converted Ringfield. Tweaking CV2 makes no difference. There are plenty of YouTube videos by people who’ve successfully converted older (and tattier) J83’s etc to dcc operation, but obviously not with HM7000 Bluetooth chips and control. I’m now considering buying a Select or Elite controller so I can connect (via a Donegal) to a “quality” decoder: an expensive route to run cheap old locos, but this is something I really want to do. If a controller is the answer, will a Select be adequate when operated via the Donegal etc? Bottom line: are the HM7000 decoders “weak” in some way? Link to comment Share on other sites More sharing options...
96RAF Posted April 2 Share Posted April 2 Are you running the latest version of your chosen profile as earlier versions would stall. The decoders are 1 amp capable continuous so definitely not weak. You may like to consider fitting a power bank which will definitely cure your problem, which could be dirty track or wheels or poor pickup contacts. Link to comment Share on other sites More sharing options...
ateshci Posted April 2 Share Posted April 2 (edited) This can happen when the motor is 'noisy' due to brush residue in the collector gaps. It will create current/voltage spikes then that hamper BT connection and may even upset the on-chip controller. A test would be to switch BT operation off and run by DCC - to show the severeness of the problem. If it stalls there too, a thorough cleaning of the motor is in order. In 'lighter' cases I've taken the motor out and ran it on 20..25V DC to burn the residue away - caution, you have to monitor the current draw. If it stays higher than 150mA for more than 30secs, the motor must be cleaned by other means, or may be faulty Edited April 2 by ateshci Link to comment Share on other sites More sharing options...
Rallymatt Posted April 2 Share Posted April 2 Can I suggest this is moved to the HM DCC section as it’s not TT:120 and more appropriate responses will be made there Link to comment Share on other sites More sharing options...
Fishmanoz Posted April 2 Share Posted April 2 HM | DCC, not DCC! Link to comment Share on other sites More sharing options...
ColinB Posted April 3 Share Posted April 3 (edited) On 02/04/2024 at 09:13, George-351466 said: I’m returning to an issue previously referred to in passing, but now really bugging me. What is the reason why HM7000 chips cut-out when fitted to older locos? Yesterday I made a concerted effort to get my (quite new and little used) J83 to run with a Bluetooth chip. It’s connected via a fitted plug-in socket, so no hot wiring. It runs fine in analogue (with blanking plug) and linking via iPhone is no problem. All is fine on screen and sounds are all there, but……when movement is attempted there’s an initial twitch, then the loco freezes and the link is lost shortly after. It will not re-connect to the phone unless the transformer is switched off and the app closed then re-started. I’m having the same issue with a cd converted Ringfield. Tweaking CV2 makes no difference. There are plenty of YouTube videos by people who’ve successfully converted older (and tattier) J83’s etc to dcc operation, but obviously not with HM7000 Bluetooth chips and control. I’m now considering buying a Select or Elite controller so I can connect (via a Donegal) to a “quality” decoder: an expensive route to run cheap old locos, but this is something I really want to do. If a controller is the answer, will a Select be adequate when operated via the Donegal etc? Bottom line: are the HM7000 decoders “weak” in some way? I don't know what your setup is, in that do you have a DCC controller? If you do then what I suggest is after you have converted your older locos to DCC, test them with a decent high current decoder. I am going to say a Zimo one because I have found to be the best at driving older locos and believe me I tried many when I converted mine. I will add I have no financial interest in Zimo, I just find them to be the most reliable. If if works with one of these then it proves your conversion is correct. Then try it it with the HM7000. On a lot of my old Hornby 0-6-0 locos I use a 6 pin connector for the conversion and initially because they were cheaper I would use cheap N gauge decoders mainly because Zimo ones are in the order of £30 plus. Surprisingly a lot would exhibit the behaviour you are getting. For some reason certain decoders don't always work. On all of them I checked the maximum output current in the specification but come to the conclusion that there might be some artistic license in there somewhere. I have only ever used HM7000 with my brand new locos from Hornby, so I can't really comment as to whether they will work with older locos. Edited April 3 by ColinB Link to comment Share on other sites More sharing options...
ntpntpntp Posted April 3 Share Posted April 3 Firstly, I'd say check the loco wheels and track are scrupulously clean and all wheels which should pick up power are doing so. Secondly, run the loco on DC and check the current draw with a multimeter in series with the load. In other words, rule out the possibilities of poor pickup or current overload first? Link to comment Share on other sites More sharing options...
ateshci Posted April 4 Share Posted April 4 (edited) Lest I forget -sometimes the hf current ripple ( same as the noise I referred to ) is too much for the decoder to tolerate. One can try to wire an inductor of 0.56mH ( maker: e.g. Delevan ) in series with the motor, as the resistive value of 4 Ohms is just tolerable @200mA and the additional space requirement of 8x11mm (dxh) can be tolerated in most cases. Sometimes even smaller inductors have helped, but that's a matter of trial and error ( or black magic 😀) Edited April 4 by ateshci Link to comment Share on other sites More sharing options...
96RAF Posted April 4 Share Posted April 4 Folk often forget that the decoder maximum output includes functions like sound and lights as well as motor load and any other gismos the loco has to run with like powered fans, etc. 21 hours ago, ColinB said: the maximum output current in the specification but come to the conclusion that there might be some artistic license in there somewhere Link to comment Share on other sites More sharing options...
ColinB Posted April 4 Share Posted April 4 15 minutes ago, 96RAF said: Folk often forget that the decoder maximum output includes functions like sound and lights as well as motor load and any other gismos the loco has to run with like powered fans, etc. I know I did all that, I found it to be a big issue with 6 pin decoders, put in one make and the loco hardly moves put in another and no issue. One of the first things I generally do is check the current rating, plus on virtually all my steam locos there are no functions used. That is why on older locos I exclusively use Zimo decoders. Link to comment Share on other sites More sharing options...
George-351466 Posted April 4 Author Share Posted April 4 Many thanks for the helpful replies. Some are a little technical for me, but to simplify, I am operating via Bluetooth solely and track etc is clean and loco motor (for the J83) is the latest, I believe, brushless type, little used. But, despite my initial belief that the loco was “clean”, a common thread in responses has been about good contacts and cleanliness in general. And so I totally dismantled the loco, cleaned pick-ups and increased contact tension to the wheels. I then cleaned the wheels, particularly the rear sides where the brush pick-ups contact, after which all was reassembled with light oiling. I also added lead weight onto the inner sides of the water tanks where there’s plenty of space, before finally borrowing a power bank from another loco (please Hornby, when will these be available again?). I was determined to do all possible before another attempt at running and I confess that tension was rising as I went through the 15 or so minutes of linking and profiling before touching the dreaded speed slider. But eureka, it worked. So, thanks all for the advice. I then decided to really test the limits of these decoders by linking one to a Triang Davy Crockett - admittedly running on a new Hornsandwhistles 5 pole motor, but via the original wheels and pick-ups. Everything scrupulously cleaned and adjusted and power bank again borrowed. To my delight it also worked!!! A Davy Crockett set chuffing, tooting (Merchant Navy profile 🤣) and squeaking around the layout caused huge amusement. The final test was to run both, but minus the power banks; but we were back to stalling and disconnecting. It was an interesting, educational and happily satisfying day of experimentation, but the principal lesson is that power banks are essential. Just why this should be is unclear (to me), but I won’t lose sleep over that as I’m just delighted to have got these things working and that the HM7000 decoders are not “weak” at all. Now, please can we have more power banks, or is there an alternative stay alive? 2 Link to comment Share on other sites More sharing options...
George-351466 Posted April 4 Author Share Posted April 4 (edited) Subsequent posting deleted as erroneous. Edited April 4 by George-351466 Incorrect posting Link to comment Share on other sites More sharing options...
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