Reply to "Weak DCS signals, Failed TIU Output Drivers, and Design Solutions devloped under collaboration between AGHR and MTH"

gunrunnerjohn posted:

Ryaninspiron posted:

So would you say that this TVS diode (due to its size) solution can be expected to last as long as Adrian's 1n4148 solution?

I am torn a bit on which solution to suggest for my club considering they have 5 TIUs all channels in use, and I can get 100 1n4148 delivered from amazon in one day for $5. 

Both solutions (Adrian's "beefy clamp" board and your smaller board) are attached to the 74ACT244 right? 

Either of these solutions supplant the MTH accepted (Service Bulletin 5-22-18A) fix right?

In general is it a sign of bad TVS diodes if each TIU (PASSIVE MODE) output channel is drawing 0.2Amps? One of main rail lines(several hundred feet long) has a 2 Amp draw with an empty track as soon as the TIUs are connected.

Mine just sits on top of the ACT244, it's fairly easy to install, but it does require some "fine" soldering to the ACT244 leads.  I use #30 wirewrap wire to make the connections.  I did a "final" tweak to the layout, but I haven't built any of these yet.  Electrically, they're the same as the previous version, I just put some holes for the wires as it makes it a lot easier to keep them from coming loose as you solder the other end to the chip lead.  Even with #30 wire, enough heat came up the wire to unsolder it, it was a bit of a pita.  With the holes, you can tun the wire through and lay it over, even if it momentarily melts the solder, the wire won't just fall out.

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I've only put this on a couple of TIU's, and I don't get the abuse that Adrian's club dishes out, but there have been no failures and no channel degradation.  Obviously, it would be nice if it had a wider exposure before declaring it a "tested" fix, but I believe it is doing the job.

 

Thanks for the feedback. I have done a good bit of work with wire-wrapping wire in the past and agree that is certainly an easy way to make the hookup. The club I am in certainly runs a lot of trains both DCS and Legacy, I am hoping to get to the bottom of their DCS issues and I have a feeling this could be it.