# The 7B and 8B Transformers.



## T-Man (May 16, 2008)

Recently I was reviewing my inventory of small transformers and noticed I had some 7B and 8B models.
You have to admit they have the coolest operating throttle handles!.






























Case removal is easy. One screw for the handle and two for the case. The first objective was to change out the wire and plug. The connections are at the bottom. To replace the wire entirely four base supports need to be drilled out and replace with nit and screws. To avoid that I saved three or four inches of the original wire and used wire nuts to connect to the new wire.


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## T-Man (May 16, 2008)

A common problem with this transformer is a loose handle. The handle is attached to a brass shaft that is staked to a clip. Over time this gets loose. I removed the white metal clip from the insulated disc and reset the brass to the clip with a hammer and drift pin. No more wobble. The clip being made of white metal I was careful with the tabs and used epoxy when I reassembled it. Two of transformers were loose.


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## T-Man (May 16, 2008)

One peculiar thing about these transformers is the wooden handle part was missing. I never checked to see if it was an available part but I built my own with a clothespin. The original had a screw going through the whole length. Size 6 screw with 32 thread. I improvised.


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## alaft61ri (Oct 11, 2019)

pretty cool


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## AF-Doc' (Dec 21, 2013)

Very nice and rewarding work.
Doc


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## T-Man (May 16, 2008)

Practicing with Tiny Cad, here is an electrical diagram of the 8B. The circuit breaker was left out but part of it is shown here.
The common contact point which is in the lower left corner is attached to a circle. From what I surmise A heater band(not shown) forces the wheel, counter clockwise and the contact point lifts 1 breaks the connection, 2 turns on the red light.


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## shaygetz (Sep 23, 2007)

My Transformers don't look anything like yours...









I'll let myself out....🤪👍


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## T-Man (May 16, 2008)

The Circuit Breaker.




















On the right there is an insulated screw. The insulators and two strips are removed. On the left off the red wire you can see the contact for the red light. The groove for the top strip fits into the slot on the wheel. 










The bottom Strip has a top and bottom insulator. The button pushes down on this strip to disconnect,. The button also passes through a hole on the top strip. All the parts have a hole for the insulated screw to hold.










All the parts have a hole for the insulated screw to hold. The big insulator fits on the top of the bottom strip and the small insulator fits n the bottom of it. The last piece is missing, a threaded plate for the insulated screw. The screw in the picture holds the Circuit Breaker to the frame.


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## TimmyD (Dec 6, 2021)

T-Man said:


> A common problem with this transformer is a loose handle. The handle is attached to a brass shaft that is staked to a clip. Over time this gets loose. I removed the white metal clip from the insulated disc and reset the brass to the clip with a hammer and drift pin. No more wobble. The clip being made of white metal I was careful with the tabs and used epoxy when I reassembled it. Two of transformers were loose.
> 
> View attachment 563641


Hi T Man, I just picked up what I think is an 8B (OK and fault lights, circuit breaker), and am trying to get it up and running. The wiper has lost its connection with the post. It looks like someone tried to solder it at one time. Am I understanding correctly that you peened the wiper back on? I have been running I think 4B's, plenty of power but no circuit breaker or style, looking forward to a little style and safety. This particular one also has a different handle. No screw, concentric or radial, and probably a missing friction clip as the handle will turn the post, but pulls right off. Anyway, wondering if you could describe your fix for reattaching the wiper in a little more detail, and wondering if you have a picture of the clip that may have been in this handle. Thank you very much and enjoy your trains!
Tim


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## T-Man (May 16, 2008)

There are two wipers the lower one transfers the power, the top one under the handle is isolated and just holds the handle in place. The lower and upper wipers are isolated by a disc. It is held in place with a clip from the bottom and top. The clips do not touch, The top clip has the handle shaft staked from the underside, That is why I removed it to restake it. Sorry no pictures. The inside of the hand has that copper wiper staked in with the handle. You don;t need it. The handle has two flat sides to fit on the shaft and the screw holds it down.

The caution is not to break the top clip when separated from the insulated disc.


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## flyernut (Oct 31, 2010)

Nice tutorial and great pictures.. I love my 8B's that I have.


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## TimmyD (Dec 6, 2021)

T-Man said:


> There are two wipers the lower one transfers the power, the top one under the handle is isolated and just holds the handle in place. The lower and upper wipers are isolated by a disc. It is held in place with a clip from the bottom and top. The clips do not touch, The top clip has the handle shaft staked from the underside, That is why I removed it to restake it. Sorry no pictures. The inside of the hand has that copper wiper staked in with the handle. You don;t need it. The handle has two flat sides to fit on the shaft and the screw holds it down.
> 
> The caution is not to break the top clip when separated from the insulated disc.


Thanks T-Man! I will have to pop the cover off again as see what I have... I know the wiper is there that adjusts the voltage, but I think the disc and upper wiper are non-existant on the transformer that I have... Also, the handle I have has no set screw, so I am guessing that the upper wiper helped hold the handle on with friction or some sort of clip that didn't require a screw. Thank you very much for explaining, I now have a better idea of what I am missing, and hopefully can find a decent way to get it running. Have a wonderful day!
Tim


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## AmFlyer (Mar 16, 2012)

Just for completeness, the 4B has a built in thermostatic breaker.


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## TimmyD (Dec 6, 2021)

AmFlyer said:


> Just for completeness, the 4B has a built in thermostatic breaker.


Oops, not 4B's then... I meant the little maybe 45 watt plastic transformers and the larger 75 watt sheet metal boxes. For some reason I thought the sheet metal box transformers were the 4B's. I meant #1, #1 1/2, and #2 transformers are what I have been running. Some of the 4B's apparently look like #2's. Thanks for clarifying Tom!
Tim


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## AmFlyer (Mar 16, 2012)

Those transformers do not have breakers. The exception is some of the 1948 #2's have the same breaker as the 4B. Those are marked 2B. 
#2's are usually black, 4B's are usually gray until the case was changed to black plastic.


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