DCC Roof Fans on Heljan Western

Tim Giles

Member
Has anyone successfully managed to get the roof fans working using the Legomanbiffo Class 52 decoder.
I have got all the other functions working Ok but getting the fans to spin is something that is proving a problem.
Ideally I want them to work on F12 and related to loco speed similar to the DC version.

Regards,
Tim
 

richard carr

Western Thunderer
Hi Tim

Getting the roof fans to work on Heljan locos can be a pain.

The first question is, do the fans have a separate small pcb in the roof contolling them, or are they controllered from the main Heljan PCB ?

This is the separate roof mounted PCB in a class 50 Heljan would have used the same one in the Western.
20200202_103618.jpg

If it doesn't have one of these the same components will be on the main pcb.

It is very difficult to get the fans to run at a correct speed without these. DCC uses a constant 12-14 volts which makes the fan run really fast and noisy when the should be quite slow, the blue and white potentiometer on the board can reduce the voltage so that it runs at more realistic speed.

You won't be able to get the fan to run as it does on DC, as DC is a variable voltage system, ie as you turn the controller up it increases the voltage to make the loco run faster and does the same to the fan.

As for getting it to run on F12 I assume it's an ESU decoder and you would be best of asking Leggoman how to do it, I would use a Lok Programmer but if you haven't got one and know how to use it asking him for the CV settings to do that is by far the easiest way.

Richard
 

TheSnapper

Western Thunderer
........Getting the roof fans to work on Heljan locos can be a pain....

Hi Tim

Have you contacted Bif? He is a nice bloke & very helpful.

I agree with Richard, and almost think it's not worth the effort.
I have often thought about attempting to devise a method to drive them by air movement, like a windmill.

I did a Heljan Western here and it has a seperate fan PCB (and two sets of fans!)

I haven't tried it, but I wonder if it would work related to loco speed, just by connecting the fan feed to the motor output on the decoder, rather than to the AUX output controlled by F12.
You could trim the speed with the on-board potentiometer on the fan PCB, but the fan would be ALWAYS-ON , except when the loco is stationary.

Not sue if it might confuse the decoder back-emf. I may try it later....

(Another) Tim
 

KeithRE

New Member
Hi Tim

Have you contacted Bif? He is a nice bloke & very helpful.

I agree with Richard, and almost think it's not worth the effort.
I have often thought about attempting to devise a method to drive them by air movement, like a windmill.

I did a Heljan Western here and it has a seperate fan PCB (and two sets of fans!)

I haven't tried it, but I wonder if it would work related to loco speed, just by connecting the fan feed to the motor output on the decoder, rather than to the AUX output controlled by F12.
You could trim the speed with the on-board potentiometer on the fan PCB, but the fan would be ALWAYS-ON , except when the loco is stationary.

Not sue if it might confuse the decoder back-emf. I may try it later....

(Another) Tim
Hi Tim(s),
Just a few thoughts - I'm not familar with the particulars in this case. Could you control a small relay from one of the outputs? If so, you could use it to control the feed to the fan the motor output - a smallish value resistor ('select on test') might be useful to 'isolate' and back-emf effects but I'd expect they would be quite small compared with the two heafty Heljan motors.
Best of luck, interested to know how you get on.
Keith
 

Tim Giles

Member
Thank you all for your replies and varied interesting suggestions/solutions.
I have got quite a lot of things that I could now try.
If I succeed in achieving the effect I am looking for I'll post my solution.

Tim
 

class27

Active Member
Hi
Having just done this you will need to speak to Legoman as it requires some alteration needing a lokprogrammer. You can adjust the voltage on Aux 1 once it is configured to work with F12 and there is a light mod that he can do that gives more prototypical operation of the lights.
I now have all the fans working on both Loksound (thanks to Legoman) and my zimo Locos thanks to Paul Chetter if you play around with the voltage CV you can get very quiet operation of the fans using the small board pot for final adjustment. I have even managed to retrofit a small board to my MK1 Hymek and even it runs quiet
The fan thing has been overlooked on Heljan diesels as Gimmicky and noisy, but with some adjustment they can all work well
cheers
 

TheSnapper

Western Thunderer
Hi Tim

Just to follow up on my suggestion:
Wiring the fan directly to the motor outputs on the decoder does actually work, and fan speed increases with loco speed.
Obviously the fan stops when the loco come to a halt.
However, is this prototypical?

The fan speed will need careful adjustment using the potentiometer on the fan control board.
I found it difficult to get the the fan to start until the loco is travelling at some speed.

Cheers

Tim
 

richard carr

Western Thunderer
Tim and Tim

No it is not prototypical for the fan to stop when the loco stops. The fans are as I understand temperature controlled although having said that I don't ever recall seeing a loco with the engine running where the fan was not moving.

I also believe that the fan speed is fairly constant and does not increase with loco speed.

The problem with most decoders is that the function outputs are at full voltage ie 12, which makes the fan rotate far too fast and often makes it very noisy too.

You need to use the potentiometer that is either on the main Heljan PCB or sometimes comes as a separate PCB to lower the voltage to get a realistic spin speed.

Richard
 

Ressaldar

Western Thunderer
Hi Tim, Tim and Richard,

back in October 2018 I installed an ESU V4XL into a Heljan 47 for a fellow Club member and discussed the fan speed problem with SWDigital who had supplied the decoder. Their response was that on some Heljan diesels there is a 'pot' which can adjust the speed or if the 'pot' is not present, set

CV31 = 16

CV32 = 0

CV294 = 0 - 31 (output speed)

I adjusted the CVs and yes it does control the speed, but as stated elsewhere here, a certain amount of sound is still heard.

I hope this is of interest.

Stay safe all.

regards

Mike
 

richard carr

Western Thunderer
Hi Mike

Thats one I'll try to remember, you can do a similar thing on Zimo decoders but the voltage is controlled by pulse modulation so when you get the voltage down it does turn the fan but not on a consistent basis, sometimes it will work, sometimes it won't start at all and the fan needs a nudge to get it going.

The Heljan PCB is by far the best solution and you can buy the separate one as a spare part from Gaugemaster who are now doing the Heljan spares.

Richard
 

class27

Active Member
The pulse modulation thing is interesting and may explain why a combination of meddling with CV and the Pot gives the quietest operation
My Hymek had a really noisy fan on DC so I disconnected it for DCC until recently. I then tried it with a spare board from a class 26 and some CV info from Paul Chetter and it cannot be heard over the engine sounds.
On all of my locos with a cooler group sound, the fan noise cannot be heard over the cooler group sound.
None of the voltage CV's or pots are set the same, each loco seems to be different, but i think it is worth the effort
 

class27

Active Member
Apologies to the OP for a small Hi-jack. Does anyone out there have any Fan motors and worm shafts they do not need I need to reinstate 2. Pm if you can help
 

Tim Giles

Member
Reviewing the suggestions posted so far it would seem that a solution which emulates the prototype would obviously be the best.
If the fans are temperature controlled in the real thing then they would respond when the engines are working hard so perhaps a possible solution is to incorporate a circuit into the output to the motors which converts the current into a voltage control to the fan motors which is user adjustable. Thus when the loco is idling the fans are off, when running light then the fans just gently spin and when the loco is pulling a 10 coach train then the fans run quickly.
Looks like a challenge for the electronics experts amongst us or even the MERG members.

Tim
 

class27

Active Member
On Paul Chetters Class 25 sound project. The cooler group sounds cut in and out (just like an ordinary car would when hot) and this also switches the fan on and off without having to use the relevant F key, which is quite cool.
The big problem is the differing types of drive used in the prototypes, from mechanical, which would be speed proportional, to hydraulic and electric motor, which I guess would be single speed (flat out)
 

Spartan

New Member
Hi. I hope everyone is safe & well. Apologies for the slight thread resurrection buy I've been tinkering with a Heljan Class 45 roof fan (and Googling for suggestions - how I arrived here) and I thought I could share some ideas I have tried.

Firstly - a disclaimer - these relate to my use of Zimo sound decoders; I expect that most might be applicable to/have equivalents for decoders from other manufacturers.
  1. If you're not intending to fully implement smoke generators, you have a couple of options: function outputs for either the heater element or the smoke fan can be used to drive the roof fan. The main advantage of re-assigning these function outputs is PWM can be individually configured (separate CV settings) according to whether the loco. is at a stand, steady speed or accelerating. You can even set a time-out to stop the fan (presumably intended to stop overheating of the smoke generator components).
  2. If you're not intending to use the uncoupler function, this too can be reassigned to roof fan use with tailored PWM value set via CV, although it would be a constant speed while the function is activated.
Finally, a note on Paul Chetter's sound projects as mentioned in the last comment above. By the by, the results he achieves are predominantly why I generally choose Zimo but that is not the point I wanted to make ...

Hidden (at least partially) in the Zimo documentation are references to "trigger sounds" or (rather more meaningfully albeit verbosely) "connection between sounds and function output".

Typically, function keys are used to initiate (and terminate) both sounds and function outputs. However, the aforementioned "trigger sounds" allow that relationship to be reversed somewhat so that when a sound is initiated - by whatever means (function key, switch input, random generator) - an associated function key (or, interestingly in this context, the smoke generator fan) will be virtually activated, as if you had pressed the associated function key directly. That is a "pretty cool" feature in my opinion but it's utility increases further when you realise that it has another unexpected (not mentioned?) but potentially beneficial behaviour, best illustrated by an example I hope:

Say you have configured function key, F15, to activate the fan sound and also the function output for the actual fan. When you press F15, you hear the sound and the fan turns - great! When you release F15, the fan stops but the sound may continue for some time (depending upon the sound recorded and how the sound project is configured). I think this is to be expected but it's not completely satisfactory.

If instead you have configured key, F15, to activate the fan sound ONLY but also configured the trigger sound for the roof fan function output to be F15, it behaves as before but - neat bit! - the function output continues for as long as the sound is played/heard. So if you release F15 and the sound continues for some time after so also will the fan continue to turn. This feature comes into it's own if you assign the sound to one of the random sound generators (Z) - no need to press F15 at all if you don't want to ...​

If you put all these ideas together, you can do what I ended-up with: assign the roof fan to the smoke fan output to have varying speeds at different locomotive speeds; time-out the fan so that it stops occasionally but then restarts according to the random sound generator.

P.S. After all that I disconnected the Heljan fan because I decided I simply couldn't abide the racket it (the fan assembly) makes - just a distraction, even with the real fan sound playing over the top. :rolleyes:
 

TheSnapper

Western Thunderer
Interesting stuff David.
I have found with Heljan roof-fans that it's best to give them as much juice as possible from the decoder & control the speed with the on-board potentiometer, rather than using the low-voltage connection or a CV adjustment. They seem to be less noisy this way.
Cheers
Tim
 

richard carr

Western Thunderer
I have to agree with Tim, if you are going to power the fan the best thing to use is the potentiometer on the Heljan board.

The bigger problem though is that some of the heljan fan units are so noisy you just cannot use them, and it just varies from loco to loco and I can't see any reason for it.

Richard
 
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