Digitrax Throttle Capacitors

[karman1970]

Well, that wasn't as bad as I thought.  Used my rail nippers to grab the capacitors at the base where they are crimped.  Gave them a squeeze and they deformed but didn't break open.  I was able to rotate them back and forth half a dozen times or so and they popped loose.  The plastic bases just fell off the board after that.  Took my 30W iron (it has a 15W setting as well that didn't do jack) and some small tweezers and was able to get all 4 leads off the pads in a few minutes.  Now I just need to order some replacements.

[peteski]

I cringed when I read what you did. You were lucky that rotating the cap didn't pull those delicate solder pads up!  I would have never tried that.  I would have just cut the capacitor with the rail nippers (without any rotation), then remove the plastic base and then unsoldered the lead.

What do you mean about the 15W setting on the iron  not doing "jack"?  It didn't heat up at all, or it did heat up, but not enough to melt the solder?

[karman1970]

I cringed when I read what you did. You were lucky that rotating the cap didn't pull those delicate solder pads up!  I would have never tried that.  I would have just cut the capacitor with the rail nippers (without any rotation), then remove the plastic base and then unsoldered the lead.

What do you mean about the 15W setting on the iron  not doing "jack"?  It didn't heat up at all, or it did heat up, but not enough to melt the solder?

Well, I was planning on cutting the capacitor open with the nippers, but as soon as it deformed I could tell the base was no longer attached to it.  I figured I'd wiggle it a little and see what happened.  The leads fatigued and snapped after a couple wiggles and then the base came right off.  I agree, probably not the best way to do it, but it worked out alright this time.

It gets hot on the 15W setting, but never enough to do anything with it.  Barely able to tin it on that setting usually.  Old Radio Shack iron that I have not taken the best care of.  Works alright on the 30W setting.  All my other irons are 45W, so I figured I'd try this one first and work my way up in power until I found one that worked without just melting everything.

[reinhardtjh]

I cringed when I read what you did. You were lucky that rotating the cap didn't pull those delicate solder pads up!  I would have never tried that.  I would have just cut the capacitor with the rail nippers (without any rotation), then remove the plastic base and then unsoldered the lead.

What do you mean about the 15W setting on the iron  not doing "jack"?  It didn't heat up at all, or it did heat up, but not enough to melt the solder?

I wasn't going to post this, but since it's basically been said... 

 

That was posted in one of the repsonses to the Post in the Digitrax group.

[peteski]

 
Um, I don't like that video at all.  I would not twist-off caps like that (I'm still cringing), and I would not replace them with standard tantalum caps (well, maybe I would consider polymer-tantalum).  But hey, if it works for that guy, all the power to him.

[reinhardtjh]

To be fair, at one point he does say he wouldn't do it if the traces looked "fragile", but still...  I shuddered.

[peteski]

To be fair, at one point he does say he wouldn't do it if the traces looked "fragile", but still...  I shuddered.

All the traces under such small SMD devices are fragile (because they are so small).  There are also many types of PC board materials with different thickness copper cladding, and different types of adhesives used. Of course also consumer-grade and military-grade.  Most consumer devices use the cheaper PC Boards (which is also more fragile).  Maybe Digitrax specified better quality PC Boards for those throttles, since the pads didn't delaminate.  But I wouldn't take chances - as an electronic hardware technician, in my day I have wrecked enough PC Board traces to know better now.

[karman1970]

Thank you all for the feedback and advice.  I got 2 replacements and a spare ordered from Digikey.  Hopefully I'll have an update in a week or two once they show up and I find some time to dig back into it.

[karman1970]

Well hell, it worked!  Put the new caps on the board this morning (Digikey 493-15371-ND).  I was worried for a minute because when I first plugged it in I got nothing, no signs of life.  I unplugged it and popped the cover off to see if anything had come loose.  It all looked good, so I plugged it in and it came to life.  Been using it for the last hour.  Thank you all for the help; saved me a nice chunk of change vs buying another newer throttle.  Hope this helps someone else in the future

[peteski]

Well hell, it worked!  Put the new caps on the board this morning (Digikey 493-15371-ND).  I was worried for a minute because when I first plugged it in I got nothing, no signs of life.  I unplugged it and popped the cover off to see if anything had come loose.  It all looked good, so I plugged it in and it came to life.  Been using it for the last hour.  Thank you all for the help; saved me a nice chunk of change vs buying another newer throttle.  Hope this helps someone else in the future

Congratulations!
But according to @Ed Kapuscinski (in another thread) what you did is against the grain of today's planned-obsolescence, disposable-products society.  And I cheerfully aided and abetted in this dirty deed.   

[reinhardtjh]

And I cheerfully aided and abetted in this dirty deed.   

Check out the stage background around 1:27

[peteski]

Cool!  Looks like a 3-dimensional stage prop!