All Marklin locos will work with all types of transformers, both white and blue.

There is a danger in using older blue transformers with newer digital locomotives, in that the reversing pulse can be too high a voltage and end up destroying digital decoders. This is often because older blue transformers were spec'd for 220V or 110V (US) and then used with 240/230V or 120V mains, and therefore gave out more voltage than they would normally. When the reverse pulse was used, then the output voltage could be as high as 25v.

There is also a danger with blue transformers in that if one transformer had its yellow output connected to the yellow output of another transformer (along with the brown wire connected) you had the danger of mains voltage appearing on the plug pins of the 2nd transformer if the 1st was plugged into the mains.

The white transformers are properly spec'd for the mains voltage they are used with, plus supposedly have protection against 'back transforming', i.e, against 2 transformers accidentally having their yellow pins joined together. I say supposedly, because it was mentioned in another similar thread that not all white transformers have this protection, and no one knows how to tell the difference!

If your blue transformer is a 280A type, then you should have it checked immediately by an electrician, as the cable insulation in the lead and inside the transformer breaks down over time, presenting an electrocution risk.

You can still use your blue transformers to power accessories and lights, providing the transformer has been verified as electrically safe.

For the reasons given in the excellent piece by Bigdaddynz you may find that newer locos may have a tendency to initiate the reversing mechanism on older transformers when set to the maximum speed. This is only a problem where a mechanical reversing mechanism is fitted. The solution is to tweak the setting on the reversing mechanism so the spring tension is slightly higher. Equally a revesing unit that has been set up on an older transformer may not properly reverse when used with a newer transformer.

If you have either of these problems come back and you will be guided through the adjustment process.

Easy, the new transformers ain't cheap.

The price for a new 66471 transformer is around 90 euros, whereas a 2nd hand transformer can be obtained for half that or even less.

In the UK the voltage is supposed to be 230v. 230v transformers are thin on the ground. I'm sure many of us are using 220v versions and sending a healthy reverse kick to our locos!

White and blue plastic transformers seem to live happily together. If you are thinking of using a tin transformer heed the advice.

Some of you might wonder there were even blue metal transformers for 230V, not to forget the last series of blue transformers with plastic body for 230V.

Thanks for the information.
I use some old light blue ones for light etc. I did a quick check and got a reverse of 30,7v from 37540 and 28,3v from 6631. So, I will be carful and not run anny new locks on the old blue ones. (have use some delta lock and 6090 ones before a got the 6021, and they all survived.

My Marklin 6115 blue metal bodied transformer is spec'd for 230v.

Help my newish White transformer has stopped powering my locomotives,! The lights and turnouts still work, but no power to the track? Happened after some carriages with lights derailed. I thought the transformer had a safety thermal switch that would reset after a couple of minutes, but alas it hasn’t! So am using my old blue transformer with a transformer to go to 120. Any advice on how to get the white transformer to work again plse?

Exactly how fast is a cheetah with its balls kicked? Mph or kph is fine as a reference.

Doesn't it depend on what kicked the cheetah's balls?

Well... back on topic, I have one of the blue plastic case 30VA transformers. I measured the following voltages:

Line in 124V, full speed 18.1V, reverse activation 28.4V

I have used this transformer to control engines that had digital decoders without any damage. You can see that I'm pushing my luck with my reversing voltage at the max for the decoders.

FWIW: The specs on the transformer are full speed 17V and reverse 27V with a line in of 120V.

Here in Holland a 'tranny' means something completely different and has nothing to do with mrr.

Most locomotives are set to activate the reverse mechanism when a voltage of 23VAC is detected. The fastest designated running speed was I believe when the transformer had an output of 19VAC. If using an older transformer with higher voltage, the output of 16-19VAC becomes 18-21VAC, which may trigger a reverse charge if the output is on the high side. Older North American equipment was designed to work between 100-117VAC. Output is today standardized at 120VAC, so once again, older transformers will have an output that surpasses the 16VAC and 23VAC targets by a little bit.

Older transformers (195X-1970) had issues with internal wiring where the cord deteriorated and resulted in live voltage on the housing.
On transformers prior to the 1980s, there was a risk that a transformer connected to a layout that was not properly insulated into sections could result in a transformer that was unplugged from the wall (mains) could have a live plug voltage as it effectively took the 16VAC from the layout and converted it back to 117VAC or 220VAC as the case may be.

The 1970s and 1980s blue plastic transformers are safer, but may also yield excessive output when the reverse pulse is initiated due to changes in the line voltage in some areas. The more recent ones may already be designed to prevent the transformer from upconverting track voltage to mains levels. Some of them were already equipped with safety plugs which ensure that all transformers are plugged in with the same polarity (phase).

My recommendation would be to pick up one or two 6647 type transformers. As some have said, they can be had from broken apart start sets, but there are also dealers who sell boxed ones at good prices.

As far as those who call their transformers trannys or trannies. Maybe you should be playing with LGB instead of Maerklin. ;)

Regards

Mike C