I know that the 250 watt ZWs had the nameplate on the back but did some 275 watt versions also have the name plates on the back (early editions) or did they start right away with the new casing style? If so what years did this all happen?
Yes, the very earliest 275W ZWs had the back nameplate and the small escutcheon on top. The transition period was from the 1949 to 1950 models, but whether the 275W units with the back plate should be considered late 1949 or early 1950 models is unclear to me; I’d guess “late '49,” but that’s just intuitive, not based on any hard evidence. These ZWs turn up on eBay with some regularity.
I have one of the early 275w ZWs.
From what I can tell, except for the markings, it’s identical to the 250w ZW. It certainly has the same core, at least, with the non-laminated plates.
I don’t know the year off the top of my head, but I believe that improved “Type R” core, with the laminated stacks, came along some time in the mid-'50s. If that’s the case, that would also mean that, based on Martinden’s year information, there would also be a good many ZWs out there which came from the factory with the older non-R style core, and 275w large top plate markings. Thus, if you’ve purchased one such transformer, it doesn’t necessarily mean that an unscrupulous seller has swapped the top covers(as some sites on the internet would have you believe).
I have a 275 as well…
I’ll show you mine if you showme yours…Curious about the core.
Kurt
Okay, here are a few pictures of my two ZWs.
The first is my early version 275 watt, showing the back label
And the core
And, now, the core in my later Type R ZW
I have a 275w ZW with a smaller lionel logo on top. Does this mean its an early run of the 275W ZW, cause the nameplate on the back says 275W. Just wondering cause i seen ZW with the bigger logo on the top. thanks.
Mine’s a later model. You typically don’t see inside any of these besides your own. Thanks.
I installed new carbon rollers and rectifier disks. The rest is origional.
Kurt
I installed new roller wheels on my 275 watt ZW as well but I thought the roller arms were on the top side of my ZW. I bought my ZW used around 1967 or so.
Lee F.
I heard there are gold replacement rollers available, anybody know the availability and cost?
Heard they make the ZW run much cooler…
There was an item long ago in CTT about a dentist who replaced his ZW’s carbon rollers with gold (which he of course worked with) to keep them from getting hot. I went so far as to call him up to see whether I could buy some from him. (He wasn’t interested; and the price would have been extremely high anyway.) After thinking about it, I realized that carbon is better anyway. It provides enough resistance between two turns of the coil that it might be bridging so that the roller, not the wire, heats up. The gold would make such a good connection that it would stay cool–but the transformer winding would then take the heat.
Bob,
Do you think that the gold roller would score the windings over time?
Pure gold is pretty soft; so maybe not.
Gold will take heat well, it has even been used for heating strips in ceilings, but the cost factor is another thing to consider!!
Just looked at my ZW(the insides are the same as in the photos on here) and it needs the roller wheels replaced, must have been the KW I bought a while back that I replaced the roller wheels on.
Lee F.
Great info guys. Neat fact about the ZW R… dont have my Zws on hand but will check to see what they are tomorrow. Thanks.
I read an article in CTT back about a year or so ago probally closer to 2 anyway it stated that there really isn’t any difference between the 275 and the 250 except that they lowered the watts on the name plate to get it sold quicker as they were waiting for the UL stamp of approval but they both are accually 275 watts transformers.