question about a Z transformer

Did you test the output with a load of some kind?  If you measure it open-circuit, it will be higher.

The knob linkage is a problem are for the Z, I'd open it up and see what's going on before I used it.

How much voltage is coming out of your wall?

You might want to double check your meter against a known voltage source. The meter could be off. 

With regard to the knobs, are the knobs loose on the shafts, or do the shafts themselves appear to be loose? On a Z, the knobs have to be pushed all the way onto the shafts or they will be loose. The knob and the opening in the faceplate act as the upper bearing surface. 

ok.  I did open the Z and looked in side.  the gears are fine.  the shafts wobble.  one seems to stick a bit.  I was told that it was gone over and got a new cord ( I would hope for a new cord it could be how old).  I tried with a light bulb in between the meter and the transformer.  but got the same readings.  what do you guys and gals think??

 Some meters can be zero'd out, might want to check that as well, if your startin at 3V, when you get to 24...you'll see 27.  Also check the wall socket the transformer is plugged into.

I did zero out my meter.  and the start voltage is .7-.8v

I believe the Z puts out 25 Volts AC. Since you are reading 27 volts this could be correct since most multi meters, especilly digital ones will read plus or minus 2 or three volts.

A word of caution - Do not use the Z with TMCC engines. If you accidently turn the voltage up to the maximum 25 volts you will "smoke" a circuit board in your TMCC engine. I friend of mine learned this the hard way.

Hope this helps,

Richard

The no load voltage on the transformer will be slightly higher than the listed voltage. When you hook it up and run a train, the maximum voltage will drop a bit. This is normal with most non-regulated power supplies.

Larry

As I recall:

With the cover off, the control shafts will wobble. They are rather long, and only held by one end.

The collars on the control knobs should fit into the holes punched in the transformer's dial plate. They should wiggle just a bit. Maybe those holes are enlarged a bit, or the collars on the knobs are worn.

The knobs should have metal bands on the outside of the collar to hold them tightly on the shaft.

Back to the dial plate: I would have to look at a transformer to be certain, but I believe the holes are punched in a fashion that causes the metal to flare back into the bakelite transformer casing. so the plate not flat. Therefore, the knob's collars do not rub on an edge of the thin sheet metal dial plate. The contact a curved part of it's surface.

http://pictures.olsenstoy.com/cd/transfmr/psv4.pdf

C W Burfle you are right the dial plate holes do flare back.  it sounds like to me that i found a good one then.  i hope.  also how do i test it with a load on it??  please explain it like i know very little about this stuff.  thanks  

I am certain to be corrected if I am wrong.

Basically you can use what you have on hand.

If you have a couple of spare bulbs (12-18 volts), you can connect two in series to check the voltage range. I am not certain that it is really necessary, but I would test on the same terminals that are attached to the load.

The reason for using two bulbs is that the transformer's maximum output is more than the rated voltage of any bulbs you are likely to have on hand.

Some suggested bulbs: 53,363,57,1445 (all bayonet) 1447,1449,430,432 (all screw base)

By the way, I think the no-load results you see might be different depending on whether you are using an analog (moving needle) or digital meter.

Another thing for a load is a pair of old automotive sealed beams, they give you a decent load of 3-4 amps.  In series, they'd handle anything the transformer can put out.

C W Burfle i am using a digital meter.  i will try to two bulbs and see what i get.  

how do you tell if your carbon rollers need to be replaced?  in other words how big are they when they are new??

There should be at least 1/8" between the roller arm and the windings, when they wear down closer than that, it's probably time to replace them.  They're about 1/2" in diameter, but I don't have any in my parts box right now to measure.

I have zw rollers new they measure .400" or is in between 25/64" & 13/32" don't know if there the same

Listen to gunrunnerjohn.I just redid a post war ZW that I purchased and John was invaluable on the help he provided.Just be carefull on the roller's if you pinch the pin with too much pressure you will lock them down and they wont rotate.  

I get .3925 on the ones I have on hand, purchased long ago.

I noticed that Traindork posted the following earlier:

quote:

  I tried with a light bulb in between the meter and the transformer.  but got the same readings.

I am not quite certain what he means. The bulb(s) should be in parallel with the meter, not in series.

A little trick i do when installing new rollers.  i take a small washer approx 1/2" round, .010 thick, cut a slot in its side, slip it in between the roller and arm, then spread/peen  the pin end.  this guarntees they will turn free. remove the washer.  works every time.

Deja vu, there is a ZW thread covering rollers too. My main goof has been sideloading and bending the rivet length, before getting a good peen, not crushing them to far closed. If the rivet bends it creates a poor axle, and the brush may spin by finger but might not spin under contact arm pressure.

It doesn't take much to upset the end of the rivet so it doesn't slip out. I just squeeze the rivet a bit with a pair of ignition pliers.

I think the two sealed beam headlights I suggested would put a sufficient load on the transformer to make a difference, it always has for me.  I agree that a small bulb won't make a difference, the only reason for that is to swamp stray capacitance so a sensitive meter won't read improperly.

C W Burfle ok i can test it in parallel.  thanks  

Please check the voltage coming from the wall.  The original spec was for 110V, but many people now see 125+ volts coming out of their wall outlets, and that is enough to bump 24V up to 27V.

To expand on Dale's point, a transformer changes voltage by a certain ratio or percentage. Unlike an electronic power supply, a true transformer does not actually regulate the output voltage; it controls the relationship between the input and output voltage. So, do the math and you have exactly what Dale says - bump the input by 10-15% and the output goes up by the same amount. 

Right Dale, I have 127 volts on one side of the panel and 125 on the other side right now.  I have a dedicated transformer that only serves my house, so I get the pure power right from the source.

i will be honest i am to chicken to test my power from the wall.  i do not know how to do it safe so i am very hesitant to do it at all.  

Put the meter on the 200 volts AC scale and put the probes into the wall socket.  Make sure the insulation on the wires for the probes is not damaged.  There is nothing to be afraid of.

IMHO, people who are uncomfortable around line voltage should follow their instincts.

That written, as servoguy wrote there isn't much to performing the test.

Just make certain the probes and wires are in good condition, no damaged insulation or stray wires.

Make certain you have the probes plugged into the proper jacks, and have the range set properly (A.C. and higher than 150 volts)

Make certain you are holding the probes by their insulated handles and are not touching any metal.

Then you can safely do the test.

ok i will give it a try.  

just did it and i got 125V AC.  and you were right no sparks or anything.  

Now you know why the voltage of the transformer is high.  The transformer was designed for 110 volts, and your line voltage is 125 volts or 13.5% high, you would expect the transformer output to be 13.5% high.  

ok now i know why it is doing that