How does an electronic reverse unit get stuck?

I think that some really early "electronic" e-units actually had some relays in them - making them "electronic/mechanical" units. They will actually "click". Old relays get balky; often resolves itself with use.

Electronics can deteriorate (high-tech term) over decades so that their behavior is erratic. An expert would know the details. I don't.

If you have TMCC/Legacy or have been thinking about it, these old Samhongsa-built steamers (Weaver/brass Williams) just beg for an ERR Cruise Commander/RS conversion. Easy. Really.

As mentioned above, certain electronic components can deteriorate over time causing things like this. 

But before you condemn the reversing unit, make sure the problem isn’t your transformer. Certain modern electronic power supplies sometimes don’t fully go to zero volts, allowing just enough power to “hold” an electronic e-unit in position. To test, try cycling your reverse unit by disconnecting and reconnecting one of the two power wires to your track. If you find that your reverse unit cycles reliably in this manner, the problem is your transformer. 

TRW

The Weaver models used a qsi reverse unit. On that reverse unit you will see two grey boxes which are the relays that could get stuck.

newer electronic reverse units can get stuck when you let the magic smoke out!

You know, there is a lockout switch on a lot of electronic reverse units so you can always have it start in one direction.  If you throw the switch in neutral, it won't move at all.

Fred

As stated, relay failure. Or going a bit deeper, the transistor or ic chip that turns the relay(s) or transistor (s) on, are the most likely issues. All the other board parts are only slightly suspect; but look for toasty traces, diodes and resistors. Jumping the lockout switch and seeing if a new result happens wouldn't hurt... it would be better with a continuity test of the switch to confirm normally open or nor.ally closed as lock or run first, but it may detect a bad switch there. If your voltage drop isn't low enough to cause eunit drop out, two or four diodes pairs faced in opposite directions, in series between roller and board may lower voltage enough for e-unit drop out. Each pair eats about 0.7v, the math is pretty simple. General purpose diodes, rated over the motors max amp draw will do. I like 6a. I'd likely go 8a-10a for twin motors.

The cheap switches they use for E Unit Lock Out get dirty. The contacts don't connect all the time. Move the switch back and forth with a little pressure on it to help clean the contacts.

OK guys,

After trying several of these suggestions, it seems to be associated with TRW's post of excess voltage from a Z4000.  By physically removing power to the track, the Weaver unit changes direction without fail.  Reconnecting and using the throttle handles leaves it stuck in forward.  I noted the voltages on both cab A and cab B only go down to 1.4 and 1.6 respectively when powered down.  So... how do I correct this? 

Just as a reminder, I am running all conventional at this time due to the large amount of older brass Weaver, Sunset and Williams locomotives.

Thanks,

Troy

  I did this for an LW thread, but the basics apply. Line between +&- is a jumper. You might need bigger than 10amp, exceed the Z's max amp output. I bet they fall out at .5v.  This lowers max volt output by the same amount. Not enough current is lost to bother counting.

You could also mounted one in series on a motor lead of each train (rate over motor rating)

 

Metal case great for good heatsinking to a close match (Overating a piece stays cooler)...(as I side note I had 4a melt solder off the legs with a 3.5-4.2a bouncing draw this weekend... I'm out of 6a& over. Doubling sort of works, but is dangerous if one fails; the other can overheat.  I see it used but don't like it.

Plastic

Compact upright

Random images no idea about the company.