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If this has already been covered on the forum, my apologies.  My searches didn't turn up anything relevant to servicing these prewar "MULTIVOLT" transformers.

Ok, before you say it, yes I know many of you may be thinking "Why would you want to mess with this death trap, use a modern transformer?" or "Just put it on the self to look at." To answer these first, let me say, I like bringing old things back to life and I have a healthy respect for, training, and experience with electrical device repair.   This unit seems to be in relatively good condition and I'd love for it to be actually working and not just a static display piece.  I also plan to have it's output running through a 5 Amp Airpax Instant Breaker.  If I can replace the cord and get this to where I feel its relatively safe for adult use, I may use it for accessories.  When finished, I plan to connect it to a Variac and gradually raise the input voltage to ensure that there are no internal shorts or voltage leakage.

Before I open up the case to replace the power cord and any other recommended service, I'd like to ask for some advice from any of you who've done this, about what to be careful with inside to avoid unnecessary work or damage to the internal wiring.

To remove the top panel, after straightening the four tabs on top where the red arrows are pointing in this image>

Multivolt Type T Front panel 2-mu

My questions are:

  1. Do the 9 binding post retaining nuts need to be removed to get at the internal power cord connections?
  2. Does the knurled knob at the lever base also need to be removed?
  3. Any thing else need to come apart?
  4. On another forum, there was mention of the inside being filled with tar (or something resembling it).  Any suggestions on dealing with this?
  5. Is there anything else that needs to be done to access the power cord connections inside the case.
  6. Any other helpful hints?

Thank you, SteveH

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Images (1)
  • Multivolt Type T Front panel 2-mu
Last edited by SteveH
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One like this belonged to my dad, and I have it, although it lacks the sweep arm to change voltage. At one point I had the lettered posts connected to a rotary switch and used it as a yard cab, but it didn't really have enough juice for that. I've never taken it apart, but look forward to hearing about your progress with it.

I have worked on a number of the prewar multi volt transformers.  I do not recall if any were specifically the T, but I think they are similar.  The top does not come off, it just folds back. It is tight working in side. As I recall the cord is spliced to the magnetic wire that the primary coil is wound with.  The splice is taped.  There may be a lot of asbestos sleeving in side.   The problems I have had are there is little room to work and nothing is marked. All of the copper is corroded black.  Cleaning it prior to soldering can be difficult.

Prior to changing the cord, even prior to dissassembly, check for resistance between the prongs on the plug. There should be little or no resistance. Then check the resistance between the prongs on the plug and all of the terminal posts and the case. One Megohm or greater would be nice.   If the transformer does not pass these tests, there is probably no reason to go any farther, unless you can verify the problem is limited to the cord that is going to be changed.

Last edited by David Johnston
@SteveH posted:

...Ok, before you say it, yes I know many of you may be thinking "Why would you want to mess with this death trap, use a modern transformer?" or "Just put it on the self to look at." To answer these first, let me say, I like bringing old things back to life and I have a healthy respect for, training, and experience with electrical device repair.   This unit seems to be in relatively good condition and I'd love for it to be actually working and not just a static display piece.  I also plan to have it's output running through a 5 Amp Airpax Instant Breaker.  If I can replace the cord and get this to where I feel its relatively safe for adult use, I may use it for accessories.  When finished, I plan to connect it to a Variac and gradually raise the input voltage to ensure that there are no internal shorts or voltage leakage....

Thank you for a) wanting to do this, b) clearly stating your background and qualifications, and c) being cautious. IMO, too many folks (probably including me at one time) open up old transformers without understanding the risks and pitfalls.  Having seen many of your previous posts on electrical topics, I'm confident that you'll have a good outcome.

@David Johnston and @Chuck Sartor Thank you for the tips and suggestions.

Resistance between the 2 power cord prongs is near zero, as it should be.  No measurable resistance (2MΩ setting) between the power cord prongs and any of the terminals or wiper arm.  So far so good...

@Ken Wing and @Mallard4468 Thank you for the encouragement.

After the resistance checks, I opened it up.  I was pleasantly surprised to find that this one has no tar like substance inside.  The windings are actually coated with shellac.  Maybe this one was made towards the end of the pre-war era?

Everything actually looks pretty good inside for being at least 85 years old.

Here are some pictures of the insides (click to enlarge):

IMG_2063IMG_2064IMG_2065IMG_2066IMG_2067IMG_2068IMG_2069IMG_2070

After tightening the loose retaining nuts on the binding posts, I looked online and ordered these items to replace the line cord:

Cloth covered 18/2 cord

and

Retro look non-polarized plug

Once these parts arrive, the rest should be fairly straightforward.  Thanks again for the assistance.

Attachments

Images (8)
  • IMG_2063
  • IMG_2064
  • IMG_2065
  • IMG_2066
  • IMG_2067
  • IMG_2068
  • IMG_2069
  • IMG_2070

Success!

Well, it's been almost 2 years since I started this project, but it's essentially done now.  It only took a few hours to do the actual work and find parts.

Here's what it looks like now:

Finished

For anyone interested, here's a summary of what I did and some pictures that may help others working on similar pre-war Lionel Multivolt transformers.

Lionel Type T Multivolt Transformer Repair Notes:
Due to the possibility of asbestos, while wearing a respirator, I clipped off the original line cord and discarded it along with the brittle Bakelite wall plug.

Old Cord
Next, I tested the primary and secondary coils for continuity.  So far so good.

Bought a new 18-2 stranded line cord with cloth cover (woven over PVC jacket) and a modern vintage looking non-polarized plug.  Cleaned the top panel wiper contacts & porcelain insulator, then after stripping and tinning the wire ends installed the new cord and plug.  Note the strain relief knot, 12 gauge solid insulated wire wrap and heat shrink tubing.

Strain Relief
Tested the insulation on the windings without any loads connected to the secondaries.  Using a Variac, slowly brought the input voltage up to 130V AC input to ensure no shorting.  I kept an eye on the ammeter to ensure no current was flowing during this test.

Live Core Test
Tightened Output binding post retaining nuts on the top panel.
On the inside of the top panel, the variable (wiper) contact post internal nuts were especially loose and in some cases not making good electrical connections.

Inside Top Panel
At 120VAC input, tested all secondary fixed and variable outputs and verified correct the correct voltages were present.

Using resistive Loads, I tested the outputs one at a time up to 80 Watts each for about a minute, with no noticeable heat or unexpected sounds coming from the transformer housing.  Under load the measured voltages dropped a bit as expected.

Since it wasn't obvious at first, while reassembling I needed to use the original dis-assembly pictures I took, to find the correct locations within the lamination stack where the core support brackets were supposed to be so that everything had the correct clearances inside the housing.
Side Rails Position in Core Leaves

For anyone doing this, make sure that the 2 horizontal pieces of cardboard are put back in between the backs of the terminal screws and the secondary leads to help protect the shellacked cloth insulation on these wires.

Insulator Card

The next steps in the assembly were to reinsert the fragile cardboard that wraps around the four sides of the core and secondary wires and carefully fit the assembly back into the housing.

Before bending the 4 retaining tabs back onto the top panel (not wanting to stress them with multiple bendings), I temporarily zip tied it in place and did one more electrical test of everything to make sure there were no issues caused by the reassembly process.  One verified, I bent the tabs back down and removed the zip tie.

Now it's essentially done except for some possible cosmetic finishes.

It's still missing one of the Binding Post thumb nuts.  Although they're not an exact match, I'm probably going to get some Repro-Nickel replacements from Trainz.  Link here: https://www.trainz.com/products/lionel-1033-47-6-32-fancy-nickel-binding-post-nuts-fits-1032-1033-lw?variant=43592738013306

Maybe at some point I may try touching up the white lettering, but my fine detail painting skills aren't great and I don't want the lettering to look blotchy.  Besides, other than being difficult to read, I kinda like the well used look it has.  If you have any lettering touch-up tips to share or have an original prewar thumb nut to spare, that would be great!

When I use this, it will only be occasional and while closely supervised. For added safety, I intend to plug it into a fused 1Amp supply circuit.

I want to again thank all those who contributed their knowledge and experience here and hope this Topic may be of some help in the future to others.

Attachments

Images (7)
  • Finished
  • Inside Top Panel
  • Live Core Test
  • Old Cord
  • Strain Relief
  • Insulator Card
  • Side Rails Position in Core Leaves
Last edited by SteveH
@SteveH posted:

Success!

Well, it's been almost 2 years since I started this project, but it's essentially done now.  It only took a few hours to do the actual work and find parts.

Here's what it looks like now:

Finished

For anyone interested, here's a summary of what I did and some pictures that may help others working on similar pre-war Lionel Multivolt transformers.

Lionel Type T Multivolt Transformer Repair Notes:
Due to the possibility of asbestos, while wearing a respirator, I clipped off the original line cord and discarded it along with the brittle Bakelite wall plug.

Old Cord
Next, I tested the primary and secondary coils for continuity.  So far so good.

Bought a new 18-2 stranded line cord with cloth cover (woven over PVC jacket) and a modern vintage looking non-polarized plug.  Cleaned the top panel wiper contacts & porcelain insulator, then after stripping and tinning the wire ends installed the new cord and plug.  Note the strain relief knot, 12 gauge solid insulated wire wrap and heat shrink tubing.

Strain Relief
Tested the insulation on the windings without any loads connected to the secondaries.  Using a Variac, slowly brought the input voltage up to 130V AC input to ensure no shorting.  I kept an eye on the ammeter to ensure no current was flowing during this test.

Live Core Test
Tightened Output binding post retaining nuts on the top panel.
On the inside of the top panel, the variable (wiper) contact post internal nuts were especially loose and in some cases not making good electrical connections.

Inside Top Panel
At 120VAC input, tested all secondary fixed and variable outputs and verified correct the correct voltages were present.

Using resistive Loads, I tested the outputs one at a time up to 80 Watts each for about a minute, with no noticeable heat or unexpected sounds coming from the transformer housing.  Under load the measured voltages dropped a bit as expected.

Since it wasn't obvious at first, while reassembling I needed to use the original dis-assembly pictures I took, to find the correct locations within the lamination stack where the core support brackets were supposed to be so that everything had the correct clearances inside the housing.
Side Rails Position in Core Leaves

For anyone doing this, make sure that the 2 horizontal pieces of cardboard are put back in between the backs of the terminal screws and the secondary leads to help protect the shellacked cloth insulation on these wires.

Insulator Card

The next steps in the assembly were to reinsert the fragile cardboard that wraps around the four sides of the core and secondary wires and carefully fit the assembly back into the housing.

Before bending the 4 retaining tabs back onto the top panel (not wanting to stress them with multiple bendings), I temporarily zip tied it in place and did one more electrical test of everything to make sure there were no issues caused by the reassembly process.  One verified, I bent the tabs back down and removed the zip tie.

Now it's essentially done except for some possible cosmetic finishes.

It's still missing one of the Binding Post thumb nuts.  Although they're not an exact match, I'm probably going to get some Repro-Nickel replacements from Trainz.  Link here: https://www.trainz.com/products/lionel-1033-47-6-32-fancy-nickel-binding-post-nuts-fits-1032-1033-lw?variant=43592738013306

Maybe at some point I may try touching up the white lettering, but my fine detail painting skills aren't great and I don't want the lettering to look blotchy.  Besides, other than being difficult to read, I kinda like the well used look it has.  If you have any lettering touch-up tips to share or have an original prewar thumb nut to spare, that would be great!

When I use this, it will only be occasional and while closely supervised. For added safety, I intend to plug it into a fused 1Amp supply circuit.

I want to again thank all those who contributed their knowledge and experience here and hope this Topic may be of some help in the future to others.

Thanks for the excellent summary - you've provided a great service to the rest of us.  I have a Meccano transformer of similar vintage; after reading this, I think it's going to remain as a paperweight.

Nice work Steve. I have a similar "Type B" that came with a M-10000 set (I have the train too). I've tested mine and it works fine but I do need to change the cord. Good to know what I'd be up against if /when I open it.

2019-12-23 18.19.382019-12-23 18.20.18

The set also had Lionel's # 95 variable rheostat.....now this does have asbestos in it so it's wrapped in plastic for now. And yes- I know how to handle the stuff.....

2019-12-23 18.19.49

Bob

Attachments

Images (3)
  • 2019-12-23 18.19.38
  • 2019-12-23 18.20.18
  • 2019-12-23 18.19.49

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