Topics

Hot Snubber

redking56@...
 

I was working under my layout today and noticed  that a stubber is hot to the touch.  The other snubbers are cool to the touch.  What could be the problem with the hot stubber.

Rich

Mark Gurries
 

Snubber will have warm resistors.  The resistor will only get warm when DCC power is present. 

If one seem hotter than the others, check the resistor and the capacitor value of the warmer Snubber compared to the others.

 I suspect the resistor may be a lower values or the capacitor may be a higher value.

On Mar 6, 2014, at 1:03 PM, <redking56@...> <redking56@...> wrote:



I was working under my layout today and noticed  that a stubber is hot to the touch.  The other snubbers are cool to the touch.  What could be the problem with the hot stubber.

Rich



Best Regards,

Mark Gurries
Electrical Engineer
DCC Website & NMRA DCC Clinics: www.markgurries.com



jazzmanlj
 

If the component values are the same for all snubbers then the voltage spikes are much greater in that area. How hot is 'hot to the touch'? Rule of thumb is if you can hold the part continuous it's less than 55C and that is acceptable. If you're uncomfortable with the heat go with a higher power resistor. Do not use wirewound resistors!

Len Jaskiewicz

Vollrath, Don <dvollrath@...>
 

The capacitor may be shorted. In that case the 100 ohm resistor may become very hot as it will be dissipating almost 2 watts. With the snubber disconnected, try measuring the resistance from terminal to terminal, or just across the capacitor, with an ohmmeter. It should measure infinite ohms or open circuit. If not, it needs to be replaced.

DonV

 

From: WiringForDCC@... [mailto:WiringForDCC@...] On Behalf Of Mark Gurries
Sent: Thursday, March 06, 2014 3:34 PM
To: WiringForDCC@...
Subject: Re: [WiringForDCC] Hot Snubber

 




Snubber will have warm resistors.  The resistor will only get warm when DCC power is present. 

 

If one seem hotter than the others, check the resistor and the capacitor value of the warmer Snubber compared to the others.

 

 I suspect the resistor may be a lower values or the capacitor may be a higher value.

 

On Mar 6, 2014, at 1:03 PM, <redking56@...> <redking56@...> wrote:





I was working under my layout today and noticed  that a stubber is hot to the touch.  The other snubbers are cool to the touch.  What could be the problem with the hot stubber.

 

Rich

 

 

Best Regards,

 

Mark Gurries

Electrical Engineer

DCC Website & NMRA DCC Clinics: www.markgurries.com

 

 





redking56@...
 

This particular snubber is hot enough that if you grasp it in your fingers and hold it for more than a second, you will burn your fingers.  It is very hot to the touch.  I am going to replace it.

Rich


---In WiringForDCC@..., <len.jask@...> wrote :

If the component values are the same for all snubbers then the voltage spikes are much greater in that area. How hot is 'hot to the touch'? Rule of thumb is if you can hold the part continuous it's less than 55C and that is acceptable. If you're uncomfortable with the heat go with a higher power resistor. Do not use wirewound resistors!

Len Jaskiewicz

jazzmanlj
 

Rich,

You should try to determine why it is running so hot! I'm assuming it's the resistor running hot. What are the values and power ratings? Have you measured the cap as to possible short as Don suggested?

Len

redking56@...
 

Len, 

I am going to go down to the layout in a few minuted and do just that.  I was surprised yesterday to discover that hot snubber.  Never noticed that before with any of the snubbers.

Rich

redking56@...
 


Can I measure with the snubber in place with the power off or do I need to remove the snubber from the bus wires?

Rich

---In WiringForDCC@..., <dvollrath@...> wrote :

The capacitor may be shorted. In that case the 100 ohm resistor may become very hot as it will be dissipating almost 2 watts. With the snubber disconnected, try measuring the resistance from terminal to terminal, or just across the capacitor, with an ohmmeter. It should measure infinite ohms or open circuit. If not, it needs to be replaced.

DonV

 

From: WiringForDCC@... [mailto:WiringForDCC@...] On Behalf Of Mark Gurries
Sent: Thursday, March 06, 2014 3:34 PM
To: WiringForDCC@...
Subject: Re: [WiringForDCC] Hot Snubber

 




Snubber will have warm resistors.  The resistor will only get warm when DCC power is present. 

 

If one seem hotter than the others, check the resistor and the capacitor value of the warmer Snubber compared to the others.

 

 I suspect the resistor may be a lower values or the capacitor may be a higher value.

 

On Mar 6, 2014, at 1:03 PM, <redking56@...> <redking56@...> wrote:





I was working under my layout today and noticed  that a stubber is hot to the touch.  The other snubbers are cool to the touch.  What could be the problem with the hot stubber.

 

Rich

 

 

Best Regards,

 

Mark Gurries

Electrical Engineer

DCC Website & NMRA DCC Clinics: www.markgurries.com

 

 





jazzmanlj
 

Measure with the power off. Use a simple ohm meter across the cap. It should read infinite resistance.

Never use an ohm meter on powered equipment.

 

Len

Vollrath, Don <dvollrath@...>
 

If the snubber is still connected to the DCC bus there may be other loads seen by an ohmmeter at the snubber, so the cap may not measure infinite ohms. An alternate technique would be to short the DCC bus with a jumper (so we know it measures 0 ohms) then use the ohmmeter to measure the cap. You should see 100 ohms of the resistor, nothing less.

OR

With DCC power on, use an AC voltmeter to measure voltage across the cap. It should be almost the same as measuring across the bus or track. Or measure the AC voltage across the resistor, it should be almost zero.

 

DonV  

 

From: WiringForDCC@... [mailto:WiringForDCC@...] On Behalf Of redking56@...
Sent: Friday, March 07, 2014 7:11 AM
To: WiringForDCC@...
Subject: RE: [WiringForDCC] Hot Snubber

 




Can I measure with the snubber in place with the power off or do I need to remove the snubber from the bus wires?

 

Rich

---In WiringForDCC@..., <dvollrath@...> wrote :

The capacitor may be shorted. In that case the 100 ohm resistor may become very hot as it will be dissipating almost 2 watts. With the snubber disconnected, try measuring the resistance from terminal to terminal, or just across the capacitor, with an ohmmeter. It should measure infinite ohms or open circuit. If not, it needs to be replaced.

DonV

 

From: WiringForDCC@... [mailto:WiringForDCC@...] On Behalf Of Mark Gurries
Sent: Thursday, March 06, 2014 3:34 PM
To: WiringForDCC@...
Subject: Re: [WiringForDCC] Hot Snubber

 



Snubber will have warm resistors.  The resistor will only get warm when DCC power is present. 

 

If one seem hotter than the others, check the resistor and the capacitor value of the warmer Snubber compared to the others.

 

 I suspect the resistor may be a lower values or the capacitor may be a higher value.

 

On Mar 6, 2014, at 1:03 PM, <redking56@...> <redking56@...> wrote:

 



I was working under my layout today and noticed  that a stubber is hot to the touch.  The other snubbers are cool to the touch.  What could be the problem with the hot stubber.

 

Rich

 

 

Best Regards,

 

Mark Gurries

Electrical Engineer

DCC Website & NMRA DCC Clinics: www.markgurries.com

 

 







asychis@...
 

A couple of questions:
 
I take it that a "snubber" is the same as a buss terminator?
 
If you are using snubbers to terminate all your busses, do they all need to use the same value for the resistor and capacitor?  It looks like the recommended values are 100 ohms and .1 mfd for the resistor and capacitor, respectively.
 
What are the consequences of changing these values?  If I had one snubber with a 100 ohm resistor and .1 mfd cap and another with a 100 ohm resistor and a .47 mfd cap, would there be problems?
 
I am starting to terminate all our busses on the club layout and want to make sure I get it right.  I thought I could easily pick up the components at Radio Shack, but at least in Amarillo they carry few components these days.  Mainly bits and pieces.  In all the Radio Shack stores in Amarillo I found six ceramic and four mylar .1 mfd capacitors.
 
That leads to a final question, is there any problem mixing ceramic, mylar and other types of non-electrolytic caps?
 
Thanks!
 
Jerry Michels
Amarillo Railroad Museum

Vollrath, Don <dvollrath@...>
 

The dissipation heat in the resistor for a DCC bus snubber will be in direct proportion to the value of the capacitor. The 100-220 ohms value of the resistor makes little difference.

0.1   microfarad is the ideal value. 0.47 uF is too big and will cause the resistor to run very hot. 0.01 uF is too small and not add enough ‘noise’ suppression to help the situation. Any type of non-polarized capacitor, except for tantalum, will be sufficient. 0.1 uF, 50V ceramic caps are adequate, small and inexpensive.

 

Yeah… RShack first substituted R/C toys then cell phones do-dads for audio amps, speakers and other useful electronic parts in many stores. That has shown up on the yearly spreadsheets as a poor business decision.

DonV   

 

From: WiringForDCC@... [mailto:WiringForDCC@...] On Behalf Of asychis@...
Sent: Friday, March 07, 2014 8:49 AM
To: WiringForDCC@...
Subject: [WiringForDCC] Re: Hot Snubber

 




A couple of questions:

 

I take it that a "snubber" is the same as a buss terminator?

 

If you are using snubbers to terminate all your busses, do they all need to use the same value for the resistor and capacitor?  It looks like the recommended values are 100 ohms and .1 mfd for the resistor and capacitor, respectively.

 

What are the consequences of changing these values?  If I had one snubber with a 100 ohm resistor and .1 mfd cap and another with a 100 ohm resistor and a .47 mfd cap, would there be problems?

 

I am starting to terminate all our busses on the club layout and want to make sure I get it right.  I thought I could easily pick up the components at Radio Shack, but at least in Amarillo they carry few components these days.  Mainly bits and pieces.  In all the Radio Shack stores in Amarillo I found six ceramic and four mylar .1 mfd capacitors.

 

That leads to a final question, is there any problem mixing ceramic, mylar and other types of non-electrolytic caps?

 

Thanks!

 

Jerry Michels

Amarillo Railroad Museum




Flash Gordon
 

Here is a little item I had overlooked.  Quoted from http://www.wiringfordcc.com/track_2.htm


"Solution for unterminated bus ends:

The name of this problem suggests the solution - terminate your bus ends. This is simple and inexpensive to do. Just put this "RC network " at each end of your long buses. Yes, you will need two of these circuits for each bus ­ one at each end."

What does he mean  one at each end?  A buss has one end..... or do you need to put one near the booster also.

How many have done that?

Ed S

Ross Kudlick
 

Ed,

 

A track power “bus” can easily have 2 ends.  If you feed your “bus” near the middle (think of a “T”) the “bus” now has 2 ends.  Putting the booster in the middle of the “bus” run effectively reduces your “bus” length by half.  A 60-foot “bus” becomes 2 30-foot “busses.”  Many consider this as “best practice” when designing a DCC installation.

 

If you put your booster at the end of the “bus” you would only need one terminator. 

 

Regards,

 

Ross Kudlick


From: WiringForDCC@... [mailto:WiringForDCC@...] On Behalf Of Ed S
Sent: Friday, March 07, 2014 12:21 PM
To: WiringForDCC@...
Subject: RE: [WiringForDCC] Re: Hot Snubber

 

 

Here is a little item I had overlooked.  Quoted from http://www.wiringfordcc.com/track_2.htm


"Solution for unterminated bus ends:

The name of this problem suggests the solution - terminate your bus ends. This is simple and inexpensive to do. Just put this "RC network " at each end of your long buses. Yes, you will need two of these circuits for each bus ­ one at each end."

What does he mean  one at each end?  A buss has one end..... or do you need to put one near the booster also.

How many have done that?

Ed S

Flash Gordon
 

Ross,

I understand what you are saying and I have several split bus with terminator at the end.

But I still wonder what he meant by  two terminators ... one at each end.  read it again..

"you will need two of these circuits for each bus ­ one at each end."

Ed S



At 12:44 PM 3/7/2014, you wrote:
 

Ed,

 

A track power “bus” can easily have 2 ends.  If you feed your “bus” near the middle (think of a “T”) the “bus” now has 2 ends.  Putting the booster in the middle of the “bus” run effectively reduces your “bus” length by half.  A 60-foot “bus” becomes 2 30-foot “busses.”  Many consider this as “best practice” when designing a DCC installation.

 

If you put your booster at the end of the “bus” you would only need one terminator. 

 

Regards,

 

Ross Kudlick

From: WiringForDCC@... [ mailto:WiringForDCC@...] On Behalf Of Ed S
Sent: Friday, March 07, 2014 12:21 PM
To: WiringForDCC@...
Subject: RE: [WiringForDCC] Re: Hot Snubber

 

 

Here is a little item I had overlooked.  Quoted from http://www.wiringfordcc.com/track_2.htm


"Solution for unterminated bus ends:

The name of this problem suggests the solution - terminate your bus ends. This is simple and inexpensive to do. Just put this "RC network " at each end of your long buses. Yes, you will need two of these circuits for each bus ­ one at each end."

What does he mean  one at each end?  A buss has one end..... or do you need to put one near the booster also.

How many have done that?

Ed S

Bob <rehandjr@...>
 

Ed S
___________________
 t              |  |                 t      buss 1
-------------------------
                |  |
___________________
t               |  |                 t      buss 2
-------------------------
                |  |
          booster


t=terminator (2 for "each" buss)

bob



Ross,

I understand what you are saying and I have several split bus with terminator at the end.

But I still wonder what he meant by  two terminators ... one at each end.  read it again..

"you will need two of these circuits for each bus ­ one at each end."

Ed S



At 12:44 PM 3/7/2014, you wrote:

 

Ed,

 

A track power “bus” can easily have 2 ends.  If you feed your “bus” near the middle (think of a “T”) the “bus” now has 2 ends.  Putting the booster in the middle of the “bus” run effectively reduces your “bus” length by half.  A 60-foot “bus” becomes 2 30-foot “busses.”  Many consider this as “best practice” when designing a DCC installation.

 

If you put your booster at the end of the “bus” you would only need one terminator. 

 

Regards,

 

Ross Kudlick

From: WiringForDCC@... [ mailto:WiringForDCC@...] On Behalf Of Ed S
Sent: Friday, March 07, 2014 12:21 PM
To: WiringForDCC@...
Subject: RE: [WiringForDCC] Re: Hot Snubber

 

 

Here is a little item I had overlooked.  Quoted from http://www.wiringfordcc.com/track_2.htm


"Solution for unterminated bus ends:

The name of this problem suggests the solution - terminate your bus ends. This is simple and inexpensive to do. Just put this "RC network " at each end of your long buses. Yes, you will need two of these circuits for each bus ­ one at each end."

What does he mean  one at each end?  A buss has one end..... or do you need to put one near the booster also.

How many have done that?

Ed S

Vollrath, Don <dvollrath@...>
 

You do not need an R/C network or snubber on the DCC bus connected close to the booster.

The internal circuitry of the booster output stage should already contain components with characteristics that essentially perform that same function.

DonV

 

From: WiringForDCC@... [mailto:WiringForDCC@...] On Behalf Of Ed S
Sent: Friday, March 07, 2014 11:21 AM
To: WiringForDCC@...
Subject: RE: [WiringForDCC] Re: Hot Snubber

 



Here is a little item I had overlooked.  Quoted from http://www.wiringfordcc.com/track_2.htm


"Solution for unterminated bus ends:

The name of this problem suggests the solution - terminate your bus ends. This is simple and inexpensive to do. Just put this "RC network " at each end of your long buses. Yes, you will need two of these circuits for each bus ­ one at each end."

What does he mean  one at each end?  A buss has one end..... or do you need to put one near the booster also.

How many have done that?

Ed S




Flash Gordon
 

Bob,

Yes I see ...  and you should put the booster in the middle of a long bus, so it does make sense that way.

I was thinking

 booster -------------------------------------------------- terminator

which is not a good idea.

If you look at the web page, just above the terminator section, it shows your configuration for long bus.

Thanks
Ed S


At 01:01 PM 3/7/2014, you wrote:
 

Ed S
___________________
 t              |  |                 t      buss 1
-------------------------
                |  |
___________________
t               |  |                 t      buss 2
-------------------------
                |  |
          booster


t=terminator (2 for "each" buss)

bob



Ross,

I understand what you are saying and I have several split bus with terminator at the end.

But I still wonder what he meant by  two terminators ... one at each end.  read it again..

"you will need two of these circuits for each bus ­ one at each end."

Ed S



At 12:44 PM 3/7/2014, you wrote:
 

Ed,

 

A track power “bus” can easily have 2 ends.  If you feed your “bus” near the middle (think of a “T”) the “bus” now has 2 ends.  Putting the booster in the middle of the “bus” run effectively reduces your “bus” length by half.  A 60-foot “bus” becomes 2 30-foot “busses.”  Many consider this as “best practice” when designing a DCC installation.

 

If you put your booster at the end of the “bus” you would only need one terminator. 

 

Regards,

 

Ross Kudlick

From: WiringForDCC@... [ mailto:WiringForDCC@...] On Behalf Of Ed S
Sent: Friday, March 07, 2014 12:21 PM
To: WiringForDCC@...
Subject: RE: [WiringForDCC] Re: Hot Snubber

 

 

Here is a little item I had overlooked.  Quoted from http://www.wiringfordcc.com/track_2.htm


"Solution for unterminated bus ends:

The name of this problem suggests the solution - terminate your bus ends. This is simple and inexpensive to do. Just put this "RC network " at each end of your long buses. Yes, you will need two of these circuits for each bus ­ one at each end."

What does he mean  one at each end?  A buss has one end..... or do you need to put one near the booster also.

How many have done that?

Ed S

redking56@...
 


I measured the snubber and got infinite ohms.
The resistor is 100 ohm, 1/2 watt, and the capacitor is 0.1 uF, 50 WVDC.
All of my snubbers have these same values, and all of the others are cool to the touch.
Should I just replace the hot snubber?

Rich

---In WiringForDCC@..., <dvollrath@...> wrote :

The capacitor may be shorted. In that case the 100 ohm resistor may become very hot as it will be dissipating almost 2 watts. With the snubber disconnected, try measuring the resistance from terminal to terminal, or just across the capacitor, with an ohmmeter. It should measure infinite ohms or open circuit. If not, it needs to be replaced.

DonV






 



Skip Barber
 

How difficult would it be to swap snubbers ans see if the problem moves with the snubber?


Skip


On Mar 7, 2014, at 18:52, <redking56@...> wrote:


I measured the snubber and got infinite ohms.
The resistor is 100 ohm, 1/2 watt, and the capacitor is 0.1 uF, 50 WVDC.
All of my snubbers have these same values, and all of the others are cool to the touch.
Should I just replace the hot snubber?

Rich

---In WiringForDCC@..., wrote :

The capacitor may be shorted. In that case the 100 ohm resistor may become very hot as it will be dissipating almost 2 watts. With the snubber disconnected, try measuring the resistance from terminal to terminal, or just across the capacitor, with an ohmmeter. It should measure infinite ohms or open circuit. If not, it needs to be replaced.

DonV