HI, I need a replacement transformer for a Philips Jubilee 5 Model 123 circa 1950. It is the flat type mounted through the chassis with the tappings underneath.

It has:
A common primary with tappings for 220 to 240V or 240 to 250V.
A centre tapped secondary at about 250V output for each winding
A 6.3V 1.8A output
A 6.3V 0.6A output
It has about a 60mm X 75mm square footprint

There is ample room so any transformer in any shape with those specs would do.

Cheers!

Not quite the same voltages but this could be made to work. Worth considering as a general purpose valve power transformer, esp for larger gear:

Altronics MA5399

https://www.altronics.com.au/p/ma5399-powertran-2x115v-2x6.3v-12.6v-153va-multi-tap-toroidal-transformer/

Just about every Australian made radio that uses a 6 volt rectifier, could be used as a donor transformer.
Then the primary will be of no concern, the secondary will be for use with 6 volt rectifier and the single high secondary winding will be centre tapped and around 200 volts per side. Or possibly more but it does not matter.
The Philips 123 has only a low tube count and will not draw much current.
If the HT ends up a little high, adjust it with the first dropping resistor.
I have heaps here you can have but unfortunately a little far away.
Just as a matter of interest, what is wrong with the old transformer?
JJ

Hi Ian, that altronics transformer only has 2 X 115V secondary I need 2 X 250V secondary don't I or am I missing something? I miss a lot of things If I can use it great!

Hi Johnny, I'm happy with a doner transformer, as I said there is ample room to fit most transformers. I'm happy to buy and pay postage too. If you have something I can use and you are willing to post it I will buy it from you.

To answer your question Johnny... with valves and lamps removed and through a 100W dim bulb tester, one side of the centre tap reads 135V and the other 59V. The bulb also lights about half bright.

Have you lifted the center tap, or checked the two filter caps for shorts.
If you check the circuit the center tap goes directly to the junction of the two main electros.
Just asking, as power transformers are generally very reliable. The electros not so.
I’m sure you will find a wrecked chassis for nothing near you.
If not I could organise postage cost for you.
Try locally first.
JJ

If I lift the centre tap the transformer supplies 256V from each side of the tap and the dim bulb goes out. If I lift the lead to the electro caps and leave the resistive load to chassis connected (135 Ohm) the light comes on and the voltage drops to 135V and 59V either side of the tap. The resistor gets very hot quickly so carrying a lot of load. The resistors are within spec.

I'll see what I can find locally. I don't have any old chassis with transformers in them.

Thanks

Hang on Tippy, i'm not sure the tranny has a fault.
If you lift the centre tap then the tranny has equal voltages?
Its not smoking?
That indicates the winding inside is "ok-ish".

You hook back up and the voltages go lop sided?
That sounds like a heavy assymetric load is being applied, like the winding has a chassis short part way and putting the centre tap (almost chassis potential) back loads part of the winding.

I would lift the three HT wires (ht-ct-ht) OFF where ever they are connected and do some ohmsmeter tests (if you don't have a megger).
Look for a rectifier socket to chassis arc over and short.
Look for the HT winding squeezing out sideways and touching the laminations.

With all three winding leads floating use a pilot lamp (15W) as a load (or 2 in series to get 500 volt load) and dummy load the HT winding.
If the tranny holds near equal voltages and does not fry, THERE IS NOTHING WRONG WITH IT!
It would be silly to put another good tranny into a chassis fault and be no further forward.
Fred.

Hi Fred, I did what you said it will power the light and the voltage remains stable. I don't have a megga but the resistance between CT to both HTs is about 310 Ohms.

The resistance between one HT and chassis is 399k and for the other HT only 49 Ohm.

With the HT-CT-HT floating and powered, I measure 480V between one HT and Chassis and 38V between the other HT and Chassis so it appears the HT winding is shorting to ground in the tranny.

Hi Tippy, you may be able to fix this.
These old trannies have a habit of the turns at the end of a layer squeezing out and touching metal.
You may be able to see where it is happening and just slide some insulation between the winding and the metal and pushing the wire back where it came from.
I don't know quite how the transformer is assembled and whether you can see the short. I have saved a couple of transformers this way so hope you get lucky.
Pull the tranny off and retest to check the short is HT to the metal in the tranny.
Then inspect with good light and pray.
Good luck
Fred.

Hi Fred, it's out now and is still short to the tranny body.

I looked for all that today and couldn't see anything, the winding look good with no wire adrift, I'll have another look tomorrow but it looks in good shape externally. Maybe I can carefully push some insulating material down there anyway, I'll give that a go as well. I will let you know.

I have found a replacement and it is being posted to me so hopefully I can move on with the restoration.

Thanks for your help Fred, much appreciated, I'm a bit of a novice as far as vintage radios are concerned so It's good to pick up clues from the pros.

Cheers!

Edit: It got the better of me... I checked between the coil and the laminations and it still has little sheets of insulating material in there which look intact. I can't move them so short of dismantling the whole thing I will admit defeat. Next time hopefully I can recover a shorted transformer.

Hi Tippy, fair enough, at least you have tried and learnt a bit, that's what its all about.
As the chassis does not have a fault, the incoming tranny should graft in and work normally.
Good work.
Fred.

Not exactly sure as to how this is all being measured & assessed. 123 has to have the HV CT measured preferably disconnected. The set is back biased & very common with Philips ( I have 132L) there is a cap across the back bias resistors. Accurate measuring between either end of a resistance with an electrolytic cap across it will fail.

Beware with that cap. It is neg. to CT and positive to chassis.

I have seen within different models, including my own, windings exit the side of the wrap. Provided that it has not shorted to the core and is damaged, it can be eased back (and you do not use your dirty corrosive fingers) then bogged in placed with a Mar.

One thing to do with those trannies, is not panic. If the new one shows, signs of doing the same trick, I would ensure the separating insulation between core & body at the sides is good & get the mar onto it quickly.

Currently using "Elantas" Electrical Insulation (Elmotherm VA42 Spray) I got from motor rewinder, 123L is using Araldite Philips has been run several times in the middle of Summer at a display for 8hrs & more without problems.

Moisture can be an issue with older transformers stored badly. I did run one in a real Monarch Battery eliminator a few days ago that tested to ground (core) 5.6Meg 500VDC: Its a shielded type: The metal case got grounded. Why oh Why did it have none?

For reference if anyone wants to use the Altronics transformer in a valve radio:

You have a choice for B+. Either run the 115v into a full-wave doubler or the 230v into a bridge. The existing valve rectifier could form half the bridge, just add a couple of 1N4937s unobtrusively for the other two diodes to ground. Don't connect the centre tap!

You usually need to be inventive when using general purpose replacement transformers.

Regards the Philips transformer, I have seen many of these with loose winding wire falling out from between the paper insulation layers. I normally blow the wire back with compressed air then soak the winding with rattle-can Estapol. Let it bake in the sun for a few hours (or in the oven if it's cold!) and re-check. It's always worked for me.

Having said that, in restos, I usually add a thermal fuse to vintage transformers, sleeved in fibreglass tubing. Helps me sleep at night, I don't get nightmares of houses burning down!

Hi Ian,
I had not thought about a thermal fuse, I have a number of early thirties , forties radios I have restored now operating at home, do wonder sometime about the transformers due there age. As I do not currently have a megger, I have not stress tested them. I will however get one I think.
I assume you place the fuse on the primary side of the transformer, do you the physcally place it on the external transformer housing?
What temp cutoff do you use, and is the fibreglass tube essential.
Which brand of thernal fuse do you use.

One must be careful with thermal fuses if soldering: Heat sinking the wires is desirable. I prefer to insulate with what causes minimum thermal insulation of it. There has been a massive upgrade of the electrical system here & its gone from sixties to now fuses boxes. Even the AusNet transformer went a few weeks ago as after the upgrade it started losing oil.

New house (2013) already had a sub board fed from a studio also with new installation 2012. The rest with around 600m of cable distance involved a new distribution box to feed 3 new fuse boxes in sheds and the transfer of the house studio also to it. So everything now has RCD's etc.

One RCD has already been tested by a person who used my most hated valve tester without an isolation transformer (It has none). It still beggars belief that it was allowed int the country.

The Philips Service Data sheet For Radioplayer 123 states 2V across R23 and 6.4V across R23 (35R) & R24.(80R) = 115 Ohms which is a draw of around 57mA. These are the "backbias resistors" and all cathode current passes through them. That's with a 1000 Ohm per volt meter and new parts.