I have read about the M7 overheating

Hi All. I have been reading about some Hornby Locos overheating and the “ brown blobs “suppressors or whatever  they are? actually burning. in the M7, just when I was considering to purchase another couple? The H class, which is similar to the M7 and a new Terrier. The Loco that I already own, the M7 I fitted a plug in Decoder , which obviously means that the same brown blob suppressors are still present, where if it was Hard Wired they could be removed.Fortunately “ Kevin’s Inglenook Junction “ isn’t a roomful just two planks/ modules clamped together. But is there anything to worry about? Best wishes Kevin 

OK Kevin, where did you read that please?

Hi Kevin,

There are reported issues with some decoders overheating (whatever that means, they get hot anyway) to the point of cutting out. The only real data is a report on the Hornby Forum that the stall current draw was 1.1 (presumably amps). If that is true this is a) a very inefficient motor, b) or there is serious binding of the mechanism, and c) that is too high for most decoders, which if properly designed automatically cut out. The issue seems to be with own brand decoders. Which are fine when transferred to another locomotive. I suspect leaving the RF capacitor circuitry might have a role in messing up with the BEMF feedback, resulting in a battle with the decoder. However….

All that above was not with the M7. it was an A3 tender drive with the ringfield motor. There are reports of of overheating in the class 20, class 37, and Austerity 2-8-0. There are overheating issues with the HTC One M7, which is a smart phone. Nothing to do with Hornby.

Wrapping decoders in electrical insulating tape (or heat shrink) along with inadequate ventilation appears to be the problem. So don't wrap a decoder with anything other than what it came with, and put it somewhere with adequate ventilation. Drill holes if necessary. I bought a job lot of Lenz Silver decoders a few years ago, bare electronics, they worked fine as is, covered them with wide heat shrink and they overheated. Many double sided decoders come with a plastic covering, it is heat conductive. Don't add to it. If the decoder sits on metal insulate or cover the metal. I like having decoders on top of weights or a MAZAC chassis, excellent heat sinks.

Where sound decoders usually heat up is when there is incorrect resistance in the speakers. That will quickly blow the amplifier. The reason ESU moved from 100 ohm to 4-8 ohm speakers.

Nigel

Hi Ron. Thank you for your reply. RMWEB is the place that I read it.   Best wishes Kevin 

Hi Nigel.  Thank you for your reply. The latest report was on RMWEB, the way it read? “ as if they hadn’t been converted and were running on direct current. Alas I can only report what I have read. Your mention of â€œ A 3  Tender Drive “ with Ringfield motor .  What you wrote about the  RF capacitor  and Decoder went right over my head.   Best wishes Kevin 

Hi Kevin,

I had a look and could not find it. When and who posted? What I did read was mostly due to overheating and issues with some decoders. And a lack of understanding.

What decoder do you have in your M7? Is it running hot or cutting out? Do you still have the RF circuit? It is not necessary.

BEMF counteracts the voltage generated by the motor. RF capacitors can interfere with this forcing the decoder to increase the output to the motor.

The decoder output needs to match the motor characteristics, specifically the draw currently and the stall current. Motors draw high current when starting, much less when running. No good having a 0.5A decoder when the start draw is 1A. Decoders tolerate peak draw for a few seconds, no more. Pulling a long train requires more effort. Cheap decoders do not have the same output as good ones. That is why there is a difference in price.

Slow speed shunting and a modern motor is unlikely to tax a decoder. See my previous comments about wrapping decoders.

I have a couple of old brass coffee grinders with ancient open frame motors drawing 2-4A on start. Modern can motors took that down to 1A.


Nigel

Hi Nigel.  Thank you. I have been over the history of “ google “ on my iPad and cannot find the thread that I reported earlier. But my M7 has got the plug in Decoder and nothing has been removed. So where does that leave me? And I have other Locos with Plug in Decoders . Best wishes Kevin 

I seriously doubt you will overheat your locos on your plank layout Kevin they are not going to be exactly under heavy load at any time.
On a layout like yours all the locos will move quite slowly and will only at max be going from one end of the plank to the other.
If you had a layout with a continuous loop with gradients then it may well be worth looking into the overheating problem if you were planning to leave things running for a long time.

Brian

Hi Brian.   Thank you.  I understand that, but, if there is a shadow of doubt in possible performance problems ? I would rather know about it .   Best wishes Kevin 

Hi Kevin,

If it ain't broke don't fix it! Stop worrying. Reports on the web represent a small number of people, the majority are not finding any issues.

One thing I would ask before allowing anybody to put a decoder in (Hornby, Bachmann or a third party service installer, plug in or yard wired) is the following: Is the decoder you are recommending fit for the intended purpose in this locomotive? Especially where an N-scale or mini decoder is being installed in an OO locomotive. And never install anything with less that a 1A continuous, 1.5A peak rating. Or wrap tape around the decoder. Or….you get the picture.

Old low efficiency motors (Triang and the like) are a different story. Modern motors, even those small open frame ones that Hornby uses, are efficient and only draw around 0.25A when running, 0.5A when starting.

Nigel

Hi all

This is an area where a little bit of knowledge can be a dangerous thing.

I have a leaflet printed by Gaugemaster - one of many they produce each focussing on a different aspect of their product range.  This one is about Analogue Control - you know it's a subject close to my heart!

They show, amongst other things, the walkabout GMC-HH unit of which I have 3 or 4.  These are "feedback" controller, that is they have some special magic dust inside which monitors the power draw of the motor and increases/decreases power to ensure an even speed.  Useful for gradients and light/heavy trains.

I have used these for yonks without having experiencing any issues.  But whats this?  A little footnote under an asterisk which reads "The GMC-HH unit is not recommended for use with locomotives fitted with high quality or can motors or DCC decoders".

DCC decoders - OK I get that.  "..high quality..motors.."???  I spoke to Gaugemaster who assured me that the modern Hornby, Bachmann, Dapol, Oxford, Heljan etc motors do not fall into this category (!?!), it only refers to Mashima, Portsecap stuff - maybe the things you fit into kit or scratchbuilt engines.

Its quite a relief to know that Hornby, Bachmann etc are not using "quality motors" and then, something of a shock to find that Hornby, Bachmann etc are not using "quality motors"………..

Hi Barry.  Nice to hear that you are cracking on with your layout. As far as transformer/ controllers are concerned, I only have the direct current one to test new Locos before I consider a Decoder. As you have witnessed there are no gradients and long runs. I was under the impression that Bachmann Locos had better motors than Hornby.Best wishes Kevin 

Hi Nigel . As far as any hobbies that I have entertained are concerned I have usually been careful with advances in technology, and I am dependent on good advice . Being led or guided by the experts sometimes this works out well, other times I get dropped right in it. And my choice of small Decoder is a point in case, and I am certain that Jeff ( SRman)  wouldn’t mind me mentioning him by name. As he recommended the Decoder that I purchased ( the misplaced one) to upgrade my Terrier.   Best wishes Kevin 

Hi Kevin,

As I said, I doubt that small motor in the Terrier will cause any excitement or smoking decoders. I've wired these motors up to N-scale decoders in other models. no problems!! Mini decoders from ESU or Lenz will function quite happily in large locomotives as long as it is an efficient motor. They do however have specifications approaching the full size decoder, the only compromise being a smaller output sound amplifier. Cheapo own brand decoders made by somebody else to a price are another matter. Caveat emptor.

Nigel.

Think this might be the post Kevin is referring to, third one down…..

Hornby "H" class woes - Hornby - RMweb

The 'brown blobs' are capacitors for TV interference and to improve running under DC, they should be removed if fitting a decoder.

Reading the thread on RMweb is sounds like a batch of faulty capacitors were at some point fitted into some Hornby models.


Ed

Hi Ed.  Thank you for your reply. Yes that is the thread that I was referring to. But according to one Hornby how to that I saw, they are retained and the Decoder is soldered to them, which is a strange idea as the Decoder does the work of them. Have you got an opinion on size of Decoder for a certain Loco class, bearing in mind that most of my Locos are 0-6-0’s apart from the M7. (The class 71 Southern Electric and the DEMU’s were fitted at source.)  . Best wishes Kevin 

Kevin

Jeff has fitted hundreds of decoders so the one he recommended that you have bought and put in a safe place will be absolutely fine.
If you cant find it you are then going to be limited to whatever your local model shop sells as you dont like buying from the net or mail order.
What is your nearest model shop? if they have an online site we here can look and recommend to you which one to get from them.

Brian

[user=1801]Passed Driver[/user] wrote:

Hi Ed.  Thank you for your reply. Yes that is the thread that I was referring to. But according to one Hornby how to that I saw, they are retained and the Decoder is soldered to them, which is a strange idea as the Decoder does the work of them.

Hornby 'how to's' are for fitting a Hornby decoder, must be pretty old by now and technology has moved on. Ignore 'em

Ed

[user=2137]Briperran[/user] wrote:

Kevin

Jeff has fitted hundreds of decoders so the one he recommended that you have bought and put in a safe place will be absolutely fine.
If you cant find it you are then going to be limited to whatever your local model shop sells as you dont like buying from the net or mail order.
What is your nearest model shop? if they have an online site we here can look and recommend to you which one to get from them.

Brian

Hi Brian.  Thank you for your reply. When you mentioned the net, it is more likely to be “ strangers “ on the net.As for mail order for DCC stuff I usually shop at Digitrains for a reliable quick turnaround service. Jeremy seems like a reliable bloke, with a well stocked shop.   Best wishes Kevin