Heljan O Gauge Class 37 Roof Fan

[Airport2010]

Hi

Can anyone tell me how on earth the speed of the roof fan can be slowed down to something normal on the O gauge Class 37?
 

The ESU Loksound XL that controls the loco does a great job generally, but the roof fan is clearly receiving too much power, as it spins like an aircraft propellor at full power and screams like a food blender when F12 is selected.
 

No other Heljan loco does this.

 

Doing my head in!

 

Cheers Phil

[pauliebanger]

Phil,

 

Either turn the speed down using the potentiometer on the fan PCB, or reduce the PWM duty cycle on the function output which you have used to control the fan. (Or a mixture of the two).

 

Some have found that reducing the PWM alone introduces a buzzing/humming sound when the fan is running.

 

Best regards,

 

Paul

[Airport2010]

2 hours ago, pauliebanger said:

Phil,

 

Either turn the speed down using the potentiometer on the fan PCB, or reduce the PWM duty cycle on the function output which you have used to control the fan. (Or a mixture of the two).

 

Some have found that reducing the PWM alone introduces a buzzing/humming sound when the fan is running.

 

Best regards,

 

Paul

Hi Paul. Thanks for that reply. 
When you say potentiometer, do you mean the little knurled plastic wheel which is part of the fan housing that you adjust with a tiny screwdriver? If so, I’ve looked for that already, but I don’t believe the 37 has one. I’ve seen them on my other locos, but not on this one.

 

Could you explain what PWM is? Sorry I’ve not come across that before. I’m happy installing decoders in a Janet and John process manner, but fiddling with them is scary stuff!

 

Cheers Phil

[pauliebanger]

Hi Phil,

 

OK, some of the later Heljans don't have that PCB with Pot (yes, adjust with screwdriver), so thats not possible unless you wire one in yourself.

 

PWM, Pulse Width Modulation, is a way to vary the power output. It still gives full volts (normally) but switches on and off rapidly so the power is only the average of the On and Off parts of the cycle.

 

To reduce power, the Off duration is longer than the On duration, the size of the difference being the factor producing the power reduction. This is safe for motors, but since full volts are applied, not suitable for dimming LEDs unless protective  series resistors are used too.

 

The problem with this for Hejan fans motors is that the amount of 'dimming' or power reduction required to get a good speed, also introduces  acceleration and deceleration suffucient to set up the buzzing I mentioned earlier.

 

If your decoder has a low voltage output, you could try that instead or in combination with PWM on teh output.

 

I don't use Loksound decoders, so I can give specific help regarding low volt output or how to set PWM on outputs, but check the decoder manual maybe under 'dimming'.

 

Best regards,

 

Paul

[Airport2010]

Thanks Paul I’ll take a look at the Loksound paperwork for some wise words!

[Ressaldar]

Hi Phil,

 

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

[Airport2010]

Thanks Mike I’ll have a play with those CV settings as you suggest.

 

Much appreciated!

[Airport2010]

On 23/04/2020 at 07:17, Ressaldar said:

Hi Phil,

 

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

Hi again Mike

 

I looked at those CV settings you referred to above, but unfortunately the decoder was already a perfect match to all three, so I’ve given up and admitted defeat on this roof fan. Body is now all zipped back up again and I’ll move on to other things. Cheers anyway!

 

Brgds

[norman]

Hi Phil

Did you adjust the speed by altering the values in CV 294 i.e. was there any effect upon the rotational speed?

 

[Airport2010]

20 hours ago, norman said:

Hi Phil

Did you adjust the speed by altering the values in CV 294 i.e. was there any effect upon the rotational speed?

 

Hi Norman

 

CV 294 was set at 31 when I checked before adjusting it, which initially gave me some encouragement! I then reset it to a value of 1 with no change whatsoever, then a value of 0 with the same result.
 

The sound is great when you select F12, but the fan spins like a demented food mixer!

[norman]

OK

CV294 is used to adjust the brightness of Aux 3, as this does not work for you then the fan is not connected via Aux 3.

If you look at page 63 of the ESU manual (http://www.southwestdigital.co.uk/PDF/LokSound/51972_LokSound_V40_ESUKG_EN_User-Manual_Edition-4_eBook_03.pdf) you will see that each output can be adjusted individually.  So as it's not Aux 3 try Aux 4 on CV302 or Aux1 or Aux2.  Read and record each first before adjusting. 

Don't give up - persevere and you'll get there I'm sure.

 

Edited April 29, 2020 by norman
changed if to as

[Airport2010]

Thanks Norman, I’ll report back in due course.