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Just got a new and unused DT300 off eBay yesterday. I plugged it in to my DCS50 and was greeted with a blinking screen. Reached out to Digitrax and they indicated it was a capacitor issue - and that they no longer will repair the DT300. Anyone have any advice on what capacitors I should get to try and repair it myself?
Will Digitrax tell you what the type, capacitance value, voltage rating and case size is for the capacitor(s)?Or, will they tell you which manufacturer's part number(s) they were using for replacements?
Thanks for the feedback. I reached out to Digitrax. Waiting on a response, but I'm not hopeful since it is an unsupported product.
If Digitrax isn't helpful (and I'm not very hopeful based on other responses) then you should check at the Digitrax GroupsIO mailing list. Others there have done self repairs on most of Digitrax's products. It's probably in the archives somewhere that someone has replaced the caps on a DT300. The DT300 was a most desired throttle by some as it sits right int he middle in functionality between the DT100 and the UT4. I know of several on the list that used to go to far lengths to get more of the throttles.Groups IO: https://groups.io/g/Digitrax-UsersI just did a search of messages for "DT300 cap" and there are quite a few. One thread as old as 12/15/2000One really specific thread is https://groups.io/g/Digitrax-Users/message/220241 It is recent, being posted 08/29/2019
Can you repost the information, here, for those that don't have a login for that group?
Claus Schlund \(HGM\)08/29/19 #220241 Hi List Members, I recently acquired a DT300 throttle with the dreaded “Capacitor Plague” - this has been discussed on list in the past, and the DT300 throttles are known to be susceptible to this issue. You can read more on the larger topic of “Capacitor Plague” at the link below... https://en.wikipedia.org/wiki/Capacitor_plague The symptoms of this malady are that the DT300 alternately flashes between two displays, about once per second, first displaying the voltage and then a series of numbers, this alternating pattern of displays then repeats forever The failed components are two surface mounted capacitors - they can be seen in the photo (linked below) of a factory throttle, they are the small round silver-colored components. One is above the chip marked "Microchip" and the other is below. These capacitors are inscribed with the letters "4.7 25G 003". https://live.staticflickr.com/65535/48642360371_422c385092_o.jpg After some research, I found these are (probably) 4.7 microfarad 25 volt capacitors. I figured since the throttle was already unusable, I had nothing to lose in trying to fix it myself by replacing the failed capacitors. While such capacitors are readily available for purchase, I casually went and checked my stash of spare parts. I didn't find an exact match, but found two capacitors which were 10 microfarads. That means they have about twice the capacitance of the factory part - I did not know if this would still be ok or not, but I thought I would give them a try and see what result I got. Another difference was that the the factory capacitors are surface mount style, and the ones I had came with leads for thru-hole mounting. By far the hardest part of this job is removing the old capacitors - this work is a bit tricky. The capacitors have two solder connections, and of course you can only really heat one side at a time with your soldering iron, right? I used a very fine-tip soldering iron, I heated one side of the old capacitor and used my fingernail to tilt the capacitor away from the soldering iron just a few degrees, thus raising that one side away from the printed circuit board. Don't over-do the tilt here, or else you might damage the copper traces on the printed citcuit board. I then did the same on the opposite side. Several iterations later, the capacitors came loose. One of the two factory capacitors is right next to a plastic barrier that is part of the case - I carefully trimmed away the plastic in just that area so I could access the capacitor with the soldering iron. Keep in mind that these are electrolytic capacitors and so they are polarity sensitive. The factory capacitors have a black band on the NEGATIVE side, and the replacement capacitors I used also had an indicator mark on the negative side. I then put a bit of fresh solder on the (now vacant) solder pads where the old capacitors had been, then trimmed and solder coated the leads on the replacement capacitors. The final step was to hold the replacement capacitors in place, and to then heat the joint to reflow the solder and make the final connection. You can see the end result in the image linked below - the upper replacement capacitor is black, the lower is blue, but both have the same capacitance. Even though they are larger than the factory capacitors they replaced, they still fit in the case just fine. The two failed capacitors are visible in the bottom of the image. https://live.staticflickr.com/65535/48642007793_d49603e39d_o.jpg I plugged the DT300 to a loconet plug and voila! It worked! It is now a functional throttle again. I hope this helps others who might be in this same situation. Claus Schlund
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Topic: Digitrax Throttle Capacitors (Read 3934 times)
