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Digitrax DCS 50 Throttle pot

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Digitrax DCS 50 Throttle pot
Posted by BRVRR on Friday, November 03, 2017 1:54 PM

I have a Digitrax DCS 50 Control system that has been in use for nearly 13-years.

The throttle knob is way off from the marked positions and it will rotate 360-degrees. It still works it just isn't properly aligned and no stops. Not problem with the rest of the system. The jump ports or the loconet. I use a DT400 for most things now.

I have a feeling my grandson forced the throttle at some point to cause the problem.

I contacted Digitrax and was informed they no longer support my old DCS 50.

I intend to open it up and see what can be done to restore proper functionality. Before I open it up:

Does anyone know the value/number or model of the throttle pot Digitrax used in the DCS 50?

Any assistance would be appreciated.

Thanks

Allan

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Posted by tstage on Friday, November 03, 2017 3:44 PM

Allan,

While Digitrax may no longer support the DCS 50, someone couldn't of at least have given you the part # for the potentiometer so you could order it from a place like Digi-Key or Mouser???  Should you end up opening up your throttle, the part number may actually be printed on the potentiometer so you could use that as a cross-reference.  I'd try that first then give Digitrax another call.

Tom

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Posted by rrinker on Friday, November 03, 2017 7:54 PM

 If Digitrax says they can't repair it any more (which it does, I just checked) that pretty much means they can't. The problem is that some OTHER components are no longer available, even if the pot is a common item.

 I don't have mine handy to open up but there should be a part number or value printed on the back of the pot. Anything with the same mounting hole diameter and shaft diameter, plus the actual value, should work - probably a million options. I'm pretty sure it's a simple fix, that the pot is mounted off the board and connected with wires. Just disconnect one wire at a time and attach to the new pot to keep the connections straight, then unscrew the old one and put the new one in. If it's not marked, I can take mine apart and measure it.

 

                         --Randy

 


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Posted by CSX Robert on Friday, November 03, 2017 10:14 PM

BRVRR
I contacted Digitrax and was informed they no longer support my old DCS 50.

Did you actually contact them in person?  I have never needed anything repaired, but I have heard that Digitrax is pretty good at repairing things if possible, even once they are no longer officially supported.

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Posted by BRVRR on Saturday, November 04, 2017 9:35 AM

Thanks guys for the replies.

I'll contact Digitrax on Monday and see if they can give me the part number/data on the potentiometer.

If that falls through I'll let you know what I find when I open up the DCS 50.

Thanks again,

Allan

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Allan

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Posted by rrinker on Saturday, November 04, 2017 11:23 AM

 They may be able to help, on a conditional, case by case basis. The throttle pot in the DCS50 is, I suspect, the exact same one used on the DCS51, which IS currently repairable. But they will likely tell you that if anything else is wrong beyond that, they probably can't fix it. Which, based on the description of the problem, is probably just fine.

 However, if you don't want to be without it for a few weeks, and since it is long out of warranty, it IS a simple repair to replace the pot. More mechanical than anything.

                           --Randy

 


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Posted by Stevert on Saturday, November 04, 2017 11:50 AM

BRVRR

Thanks guys for the replies.

I'll contact Digitrax on Monday and see if they can give me the part number/data on the potentiometer.

If that falls through I'll let you know what I find when I open up the DCS 50.

Thanks again,

Allan

 

 

Allan,

Have you asked on the Digitrax Yahoo list? 

There's a good chance someone there has done this repair and could give you the pertinent info.

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Posted by BRVRR on Monday, November 06, 2017 12:35 PM

Hi Guys,

I opened up my DCS 50 this morning and checked out the throttle potentiometer.

The markings look something like this:

   2F

ALPHA

  B2k

Note: the potentiometer rotates 270 degrees.

I'm not sure how to interpret markings but I did go to both the Digi-Key and Mouser sites to see if I could find it. Massive confusion.

The only thing I learned for sure was that the ALPHA brand is Taiwanese.

Can anyone help? Please.

Allan

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Allan

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Posted by Stevert on Monday, November 06, 2017 1:17 PM

BRVRR

Hi Guys,

I opened up my DCS 50 this morning and checked out the throttle potentiometer.

The markings look something like this:

   2F

ALPHA

  B2k

Note: the potentiometer rotates 270 degrees.

I'm not sure how to interpret markings but I did go to both the Digi-Key and Mouser sites to see if I could find it. Massive confusion.

The only thing I learned for sure was that the ALPHA brand is Taiwanese.

Can anyone help? Please.

Allan

 

 

Are you saying that after you opened it up, you found that the pot still turns only 270 degrees even though the handle turns 360? 

In that case, check the handle to make sure it's tight on the shaft.  Depending on how it's attached, you may be able to shim or otherwise correct the loose fit.

But if you mean it's only supposed to turn 270 degrees, but it turns 360, then yes it'll need to be replaced.

  Take as many pictures as you need to make sure you can get the replacement wired properly (too many is better than too few).  Then remove it, measure it's resistance, and buy a replacement.  Make sure you get a linear taper and not an audio taper.

Having said all that, I'll repeat my earlier advice:  Ask on the Digitrax Yahoo list.  With nearly 12,000 members, I'm sure the odds are good that someone has done that replacement. 

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Posted by rrinker on Monday, November 06, 2017 3:07 PM

Alpha is the manufacturer - Mouser carries them.

B2k means 2K, appears to be a linear taper.

This is probably it, or a suitable replacement:

https://www.mouser.com/ProductDetail/Alpha-Taiwan/RV24AF-10-15R1-B2K-3LA/?qs=8%252br4Hz5Xir%2FCukvpdPXxww%3D%3D&gclid=EAIaIQobChMI8ZD3yOyq1wIVy73tCh0RtAaTEAQYASABEgLLUvD_BwE

A whole $1.94

However - if the pot only tunes 270 degrees but the throttle handle turns 360 - the molded part where the handle fits over the pot shaft may be broken or cracked. There is no other stop, other than the oen in the pot, so if turning the throttle handle hits the stop and keeps going, it's the handle slipping on the shaft, if the pot itself ony turns the proper amount and stops.

                       --Randy

 


Modeling the Reading Railroad in the 1950's

 

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Posted by rrinker on Monday, November 06, 2017 3:15 PM

 Yes, the Yahoo list is a decent place, although in the past few days the signal to noise ratio has been pretty out of whack with 40 or 50 posts basically because someone wasn't paying attention to what button they were pressing. Now that that's squared away, should get back to standard questions and answers.

 But we do have plenty of Digitrax users here, including a few with electronics experience. Big Smile

                                    --Randy


Modeling the Reading Railroad in the 1950's

 

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Posted by BRVRR on Tuesday, November 07, 2017 12:21 PM

Randy, et al,

 I did talk to Digitrax tech support. They said the potentiometer was a common part but that they did not give out part numbers. He suggested that I open the DCS 50 and read the numbers directly from the pot.

I followed his advice with the results noted above.

I did go to the Yahoo Digitrax group. I couldn't figure out how to ask the question. The site is more than a little confusing. So that avenue is moot.

The existing pot rotated 360-degrees, with or without the handle. The handle is fine and doesn't rotate on the shaft.

I checked out the existing pot and found that the little metal tabs the hold it together were loose. I carefully crimped them down a little and the pot seems to work just fine. It rotates the 270 degrees indicated on the face of the command station but is a little rough.

I'm going to take Randy's advice and order the new one he recommended.

Thanks to all for the advice and assistance. I'll let you know how I make out when the new potentiometer arrives.

 Allan

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Allan

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Posted by tstage on Tuesday, November 07, 2017 1:09 PM

Allan,

Was this your first time on a Yahoo! Groups website?  You have to first request to become a member of that particular group then you can post questions - just like the forum here.

Anyhow, will look forward to hearing how the new potentiometer works for you.  Interesting but not surprised that Digitrax wouldn't give you the old part number - even as a reference.  I've run into that with other manufacturers before.

Tom

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Posted by BigDaddy on Tuesday, November 07, 2017 3:52 PM

It really isn't good business practice for them to keep your throttle going indefinitely after 13 years, especially with 3rd party parts.  It also invites more questions about those parts and your installation, over which they have no control over.

Henry

COB Potomac & Northern

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Posted by rrinker on Tuesday, November 07, 2017 4:39 PM

 Before you order that specifc one, check out the dimensioons. I know the VALUE and the type (linear taper, the other type is called an audio taper, the resistence changes on a logarithmic scale instead of linearly), but i did not read into it to make sure that is definitely the correct one - it was just the first one the came up google searching the numbers you read off the existing one. I'm sure the right one is either that one or something else you can get from Mouser for a similar price, and that one probably can be MADE to work, they all tend to be about the same size. But no guarantees until I go back and read the details.

 Ever since Yahoo implemented the "Neo" interface, the groups are nothing but a mess to deal with. I rarely participate, but I do still read many via daily digest emails. Posting is definitely NOT easy - starting a new topic isn't too bad, but trying to reply to an existing thread and kaaping just relevant comments is a true pain. The search is worse than the basic search here. It USED to be good, and very easy to use. Change for the sake of change - the old user interface for Groups was NOT the reason Yahoo was losing money but that must have been cheaper to change than ditching the clickbait ads laden with malware that they interspersed with the real news stories.

                    --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by rrinker on Tuesday, November 07, 2017 4:52 PM

 Upon further review....

The play stands as called. That one should work. THe only real critical dimention is the shaft length - that exact one is .335" which sounds about right. If it's too long, you can use a cut off wheel in a dremel to cut it off - just hold below the cut point with pliers to keep the force off the stop. Should be fine as-is though.

                      --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by Stevert on Tuesday, November 07, 2017 5:16 PM

rrinker

 Ever since Yahoo implemented the "Neo" interface, the groups are nothing but a mess to deal with. I rarely participate, but I do still read many via daily digest emails. Posting is definitely NOT easy - starting a new topic isn't too bad, but trying to reply to an existing thread and kaaping just relevant comments is a true pain. The search is worse than the basic search here. It USED to be good, and very easy to use. Change for the sake of change - the old user interface for Groups was NOT the reason Yahoo was losing money but that must have been cheaper to change than ditching the clickbait ads laden with malware that they interspersed with the real news stories.

                    --Randy

 

I subscribe to about 9 or 10 Yahoo groups that I follow regularly, and  probably the same number that I only visit on occasion.

Posting is easy, to start a new topic you just click on the "+New Topic" button right at the top-middle of the page.

Replying is somewhat more complicated, but not much.  When you're in the post you want to reply to,  just click on the "<-Reply" button that's now where the +New Topic" button used to be. 

You want to keep just the relevent comments?  Click on "Show message history" in the bottom of your reply window and edit away.

Having said all that, I agree the Neo interface was a step backwards, at least for folks using an actual computer instead of their phone. But that's the way or the world now, isn't it?  Scrolling incessantly to get to the bottom of a never-ending screen?

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Posted by BRVRR on Wednesday, November 08, 2017 8:51 AM

Thanks again guys.

I am a member of Yahoo groups and a member of the Digitrax group though I rarely participate or even check the site.

When I did go there the other day nearly everything was strange and confusing so I just wrote it off.

I'll order the pot suggested and see what happens.

I hate to replace the system. If I can fix it.

Thanks to all.

Allan

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Allan

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Posted by tstage on Wednesday, November 08, 2017 10:04 AM

Keep us posted how it goes, Allan...

Tom

http://www.newyorkcentralmodeling.com

Time...It marches on...without ever turning around to see if anyone is even keeping in step.

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Posted by BRVRR on Monday, November 20, 2017 8:57 AM

Hello All,

The pot came in from Mouser a couple of days ago and I finally got around to try and change them out. Unfortunately the new pot is about twice as big as the original and won't fit under the circuit board or through the hole in the DCS 50 face-plate. The original is about half the size of the new one. (Randy your comment about size turned out to be true prophetic.)

One more try for the right potentiometer.

Thanks to all.

Allan

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Allan

  Track to the BRVRR Website:  http://www.brvrr.com/

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Posted by rrinker on Monday, November 20, 2017 3:44 PM

 Well, the good thing is, Mouser has lots of filters on their search. SO you can lock it down initially to 2K value, linear taper, and the connection type. The measure the original in one of the dimensions that they have in the search and you can narrow it down further.

 Value and type are absolutely critical, size, as long as it will fit in the space. It doesn't have to be one made by Alpha.

                                 --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by BRVRR on Tuesday, November 21, 2017 9:05 AM

Thanks Randy. I'll check it out.

Tags: BRVRR

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Allan

  Track to the BRVRR Website:  http://www.brvrr.com/

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Posted by rrinker on Tuesday, November 21, 2017 10:52 AM

 I'm going away for Thanksgiving but when I get back hopefully I can open up one of my Zephyrs and measure the pot - or if you could measure the original one, depth of the body, diameter of the body, and length of the shaft, I can help look for a suitable replacement. If you look at the data sheet on Mouser, you can see where they reference the dimension. I suspect the correct one is liek the rather tiny ones that came in one fo the Arduino kits I have. They are quite small but none of them is 2K.

                                --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by hobo9941 on Tuesday, November 21, 2017 10:25 PM

rrinker

 Before you order that specifc one, check out the dimensioons. I know the VALUE and the type (linear taper, the other type is called an audio taper, the resistence changes on a logarithmic scale instead of linearly), but i did not read into it to make sure that is definitely the correct one - it was just the first one the came up google searching the numbers you read off the existing one. I'm sure the right one is either that one or something else you can get from Mouser for a similar price, and that one probably can be MADE to work, they all tend to be about the same size. But no guarantees until I go back and read the details.

 Ever since Yahoo implemented the "Neo" interface, the groups are nothing but a mess to deal with. I rarely participate, but I do still read many via daily digest emails. Posting is definitely NOT easy - starting a new topic isn't too bad, but trying to reply to an existing thread and kaaping just relevant comments is a true pain. The search is worse than the basic search here. It USED to be good, and very easy to use. Change for the sake of change - the old user interface for Groups was NOT the reason Yahoo was losing money but that must have been cheaper to change than ditching the clickbait ads laden with malware that they interspersed with the real news stories.

                    --Randy

 

 

It's almost certainly a linear taper if used for voltage and speed control.
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Posted by rrinker on Wednesday, November 22, 2017 7:01 AM

 Unless you're MRC - their "taper wound" rheostats are anything but linear - not audio taper either, but the opposite curve of an audo taper so they have big change at the low end and lesses change at the high end.

But I think we had all that established, the only issue now is physical size. and finding one that fits in the space available inside the Zephyr console.

                                         --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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