Much of the early TIU mods even predates me
, and while I am sure MTH trained techs at the time, some of that info never translated into accurate training bulletins that were distributed, though they may have been done by e-mail. If you call MTH service, Don could walk you through it.
Having said that if a TIU is functioning correctly you are worrying about stuff you probably should not.
Rev L is the last Revision hardware wise and what should be purchased. Runs on 6.10 Vers software. The TVS mod is to protect the buffer transmit chips.
The first TVS mod could not hold up under multiple and frequent spikes. Typically seen on large layouts that clubs run. The second version used a larger TVS as a resolution. Plenty of folks are running TIU with no protection and with no issues either. Or at least non that effect running trains.
The TVS mod did apply to Rev L and Rev I3A.
I have had at least one TIU that when the mod was added the DCS signal was killed, but when removed it worked great. No one can explain why.
If you are a smooth operator of a small layout with limited derailments and such your probably fine. If your a little clumsy and frequently derail, or have many relays operating accessories on your layout that can cause spikes, you might want to have the mod done.
Of course if your already operating with some level of track suppression and good breakers on your power source, you are probably fine. G
