z1000, Powerhouse 180, and TIU Questions

I power my TIU with a Z500 from a starter set. Been that way for over 3 years and no problems. As I recall from Barry's book any of the MTH Zxxx bricks can be used to power your TIU from it's Aux port. The 14 volts for accessories should be fine as well. I don't know the ratio, but the total output power is split between the two outputs, 18v & 14v. 

AudioChris posted:

... I would like to use my spare z1000's 14v terminals to power accessories as well as switches. I'm pretty sure that in and of itself will be fine but can I also power the TIU from the 18v barrel connector without an issue?

The issue is the hot (center-pin) of the TIU's "AUX POWER INPUT" jack (5.5mm/2.1mm coaxial barrel connector) is internally tied to the Black (outer-rail/common) power banana jacks within the TIU.   So if you power the TIU "AUX POWER INPUT" with the plug from a Z-1000, it is the Z-1000 "hot" connected to the layout's common.  I'm not sure if I'm expressing this clearly. 

Thanks for the replies. My TIU is sitting here on my desk and I got curious so I grabbed my meter and there is no continuity between the aux power and any of the TIU inputs or outputs. In fact, there is no continuity between the aux power and ground on the rs232 port or the audio jacks. I find that a bit odd. I'm assuming that means its isolated and probably internally rectified to DC seeing as how the manual states I can use either an AC or DC supply. If that is the case, it probably doesn't matter what polarity the barrel connector is as long as my accessory outputs are phased the same as my track power?

AudioChris posted:

...there is no continuity between the aux power and any of the TIU inputs or outputs....

Just to be clear, you have NO continuity between any of the 8 black power banana jacks and the center-pin of the AUX POWER INPUT connector? 

Correct. I have continuity between the black posts of like terminals only. Fixed 1 Input ---> Fixed 1 Output, Variable 1 Input --> Variable 1 Output, etc. No Continuity between a black post and any other point accessible from the outside of the TIU. This is a working TIU (rev I3B) with the most current software. Tests done with a Fluke 75III meter.

Well, maybe MTH changed the TIU AUX POWER Circuitry to fully isolate the AUX POWER Input from the rest of the TIU circuit.  For example, from this thread:

If the AUX POWER Input is electrically-isolated then there's no galvanic connection or path for current to flow into the TIU or rest of layout...and I see no reason why you can't "double-dip" using the two Z-1000 power outputs for your two applications.

My I3A with silver dot has continuity between the center pin on the aux port and the black on fixed  1 only.

 However if you consider the track as a piece of wire (outside rails) then there's continuity between the black on all channels unless each channel has it separated loop.

stan2004 posted:

Well, maybe MTH changed the TIU AUX POWER Circuitry to fully isolate the AUX POWER Input from the rest of the TIU circuit.  For example, from this thread:

If the AUX POWER Input is electrically-isolated then there's no galvanic connection or path for current to flow into the TIU or rest of layout...and I see no reason why you can't "double-dip" using the two Z-1000 power outputs for your two applications.

Well, yes, no, and maybe.  Even though you can't measure a connection, that doesn't mean one or more components are separating the connection, and having the different grounds may still cause issues.  It's hard to believe the later TIU versions have totally isolated channels, they're all going to be powered from the same source.  I don't think an ohmmeter test is the definitive answer.

This has aroused my curiosity? I just checked my Rev L TIU and the center Aux post is showing continuity with the common output posts. My commons are all connected on the layout, but I could disconnect a few things and check each one if needed.

Ok, I did check the channel 1 fixed output with nothing connected and it showed continuity to the center Aux pin. I had to go check further, no continuity between Aux pin and variable out 1 common. It appears mine is like Gregg's above, but I didn't actually check the fxd or var out 2 commons. 

I have been using a Z500 to power my TIU Aux port for a few years now with no problems. I also have a Z1000, but both of it's outputs are being used for other things not connected to the TIU.

Edit... GRJ posted while I was over fiddling with wires and meters.

I think title of thread should be changed to, 3 blind mice! 

If the AUX POWER Input is electrically-isolated, then you're good to go.  As GRJ says, just because you measure "infinite" Resistance doesn't mean you have electrical isolation.  Of course if you measure 0 resistance then you don't have electrical isolation.  There are many types of isolation such as capacitive-coupling, diode-blocking, and what-not that would also read "infinite" resistance using a meter.  But these are not electrical isolation in the context of a power converter which is what we are talking about.

Separately, also be-on-the-lookout for the barrel connectors that have a mechanical switch in them.  These are 3-wire connectors.  When no-plug is inserted, two of the terminals are connected, when you insert a plug into the connector, it breaks this connection; this is the cheapest and I think most common way to switch between two sources of power.  I'm not saying this is an issue here other than you ought to make measurements with a plug inserted into the connector.

You can buy a 12V DC, 2 Amp wall-wart for less than $2 (free shipping) with the correct plug (5.5mm/2.1mm).  Then you have all of the Z-1000 power available for your accessories.  Perhaps this is the path of least resistance.

Chris,

   Stan is absolutely right, use either the cheap 12VDC, 2Amp wall-wart or like many of us, use the 18/24 RS power supply with the M adaptor to power the TIU thru the Aux port.

Further if you are expanding your layout and want an economic way to set up, grab an old ZW with the 4 channels, put some 10 Amp Breakers between the old Transformer and the TIU and you have all kinds of options for running your layout.

Have fun building your layout!

PCRR/Dave