Why does the power block coming off the variable output take about 5 seconds to come on ?

Bill,

When power is first turned on to the TIU, measure the voltage, first at the Variable #1 channel input and then at the variable channel #1 output. You'll havee to cycle the TIU power twice to measure both.

Let us know if there's the same delay at both points.

I put alligator clips on the input side and turned on power and immediately got 18.6 volts. I shut off power, moved the clips to the output side, turned on power and 5 seconds later it popped on at 18.2 volts.

I should mention that a few days ago, I had tried to do some hook ups, and I'm not sure what I did, but I blew 2 of the fuses in the TIU. I think they were fixed 1 and variable 1. I replaced those and other than the delay on Variable 1, things seem to be working ok. 

The TIU takes a few seconds to power-on during which time power would flow through the fixed channels, along with a watchdog signal. However, there may be a delay in turning on the variable channels, since they, unlike the fixed channels which are wired straight through the TIU, have to turn on the circuitry that allows power to go through he variable channels.

Even if the variable channels are set to fixed mode, it's entirely possible that there could be a delay before they, too, can pass power. If I had to take an educated guess, I'd guess that this is normal TIU behavior that previously went unnoticed.

Regardless, the watchdog signal is sent out for 5 seconds on each channel, independently, only after power appears at the channel output, so that this delay is extremely unlikely to be the source of your engines coming up in conventional mode.

You say that previously you did some wiring work that went somewhat awry. I suspect that this is closely related to the  engines starting in conventional mode, and that the 5 second delay has always been present.

I'd be curious to know if others who have variable 1 set to FXD, also see this delay. Sometimes I have an FM radio on, and when I turn on the power strip for the trains, you can hear a buzzing on the radio for about 5 seconds. As you said, this must be the watchdog signal, but the buzzing stops just before the variable 1 tracks light up, and that's why I think it's tricking the engines into conventional mode.  I just tried powering on the variable1 block by itself to see if it might come on sooner, but it was pretty much the same. I did hear the watchdog signal first, then the lock ons light up. I have a 2013 NH EP-5 with PS 3 on the tracks. The headlight comes on with the lock ons and a few seconds later she powers up in idle. It's interesting that you can hear what sounds like wave forms on the radio while this is going on. So I moved the EP-5 out of the variable block, shut down the power, and when I turn it on again, you hear the watchdog signal at first, the lock ons light up, but then it's silent. Without the engine there the "wave form" sounds didn't appear.

Very mysterious. Thank you  for your input. 

If you are powering the TIU internal circuitry from the same power supply, you will get about a 3 second delay.  If you have an aux power supply that is up and has the TIU internal circuitry powered, you'll get pretty instant power.  I just checked both ways.

I have both my loops on the variable channels set to fixed so I can run conventional once in a while. I never timed it, but there is always a delay before I hear the click in the engines. I have no way of knowing when the watchdog signal appears, but they "always usually" start up silent. I say that because I had a real problem a while ago, but it was the engine at fault. John got in ahead of me, so that might explain my delay. I have the TIU powered from the track transformer so the TIU has to boot up when I turn on power.

Success !!  John, thanks for that tip. My aux power supply for the TIU was on the same power strip, so everything came on at once. I plugged the aux power into a powered outlet and now when I turn on the power strip, all power blocks come on together.

It's so easy if you know what you're doing ! 

The FM radio is interesting. The buzzing I described before when powering up is gone, instead, all the lock ons light up at once and you can hear more like a fast tapping for about 5 seconds. That must be the watchdog signal.

Thank you all for your help      Bill W.