Comments on: Toroidal Transformer Failed In Cambridge DVD Player

By: Paris Azis

Paris Azis — Mon, 22 Jun 2020 04:40:13 +0000

Thank you too Parasuraman for your detailed feedback.

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By: Parasuraman S

Parasuraman S — Wed, 17 Jun 2020 17:28:05 +0000

Yes, you have a very valid point there. I have seen SMPS TX failing and had to replace these in many CRT Tvs and a few other devices. But never succeeded in opening a Ferrite Cored Tx as it always broke!

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By: Parasuraman S

Parasuraman S — Wed, 17 Jun 2020 17:25:53 +0000

In reply to Paris Azis.

1) My experience is that the toroidal transformers are failing in may devices that I have handled. Probably the electrical condition here might be one of the reasons. 2) No it is not the same brand. That was an audio Amp and this is different! 3) The power rating has been taken care of 4) I have not checked the Transformer for idling current and the nominal current. Shall do so if it all it comes back with a complaint. 5) Ok. Shall take care of your advice, which is very valuable 6) I am fully aware of such thermal fuses inside the Transformers which are quite common in Philips. There is no such fuse inside this Tx 7) My experience is that if the thermal fuse starts failing, the health of the TX is not good and it is always better to replace it.

Many, many thanks for a detailed feedback with a lot of new ideas. It helps a lot!

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By: Parasuraman S

Parasuraman S — Wed, 17 Jun 2020 17:15:40 +0000

In reply to Humberto.

Many thanks!

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By: Paris Azis

Paris Azis — Wed, 17 Jun 2020 09:12:09 +0000

Hey Parasuraman
You have confused me with these toroidal transformers dear!
Everyone knows that they are more robust than the ordinary laminated transformers and can tolerate much wider variations in the load side or in their primaries.
Is that one the same brand with the one of your previous article, where you put the soft start circuit?
Is there any connection between the two cases? I can hardly believe that these transformers fail so easily!
This one here, for example, faces a load demand of 36V.A. (10V x 2A = 20V.A, plus 32V x 0,5A = 16V.A, making a total of 36V.A).
Obviously a 50V.A power transformer covers fully this demand and I believe that the original you replaced was of that nominal power.
Anyway, if you encounter the same failure once again, please do me the favour and measure the idling (magnetising) current. It would be good to know the percentage of the ratio of the nominal power to its idling power.
And if you are so patient and have the means for that measurement, take a temperature measurement after one hour of idling operation.
In any case, if this last measurement shows more than 50 degrees Celsius, then, for sure, the turns calculation is wrong.
In this case, we call the product a "potato" in my country!
Another crucial thing is (again if you have the patience) to remove the windings and see the colouring of the enameled wire of the primary.
I am saying this because if the primary coil keeps its natural colour, there is a chance that the manufacturer uses an internally installed thermal fuse, which you will find it open.
A have many times repaired such transformers just by bridging the thermal fuse. I was lucky, in these cases, because the fuse was installed at the end of the primary coil. I just had to rewind a new secondary (by hand of course)!
If the fuse is at the beginning of the primary, there are such cases as well, there is nothing you can do about it (by hand work)!
And it seems that many manufacturers use this method, which puts a certain death date to the transformer for the obvious reason that the fuse opens much more easily if it detects the core temperature instead of the windings'one...!! We know that as "programmed obsolescence" as someone of my readers had written in one of my articles...
Just remember my request in your next, always interesting, article!

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By: Paris Azis

Paris Azis — Wed, 17 Jun 2020 08:25:13 +0000

In reply to Tayo.

Hey Tayo
If you are interested in rewinding yourself your linear transformers, for your hobby or your own satisfaction, try to find my relevant article, here, in this blog. All the necessary data are included therein. You can also modify a blown transformer to suit a given need of yours.
Moreover, switching transformers are much more easier to rewind them provided that you can open their ferrite cores without breaking them. They are easier because they have much less turns than their linear counterparts.
The big pain is to rewind a toroidal transformer by hand. This is real torture! They have many many turns in their primary coil and the total length of the wire must pass through their internal hole once per each turn. If you can do that, you are an extraordinary human being!!

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By: JACKY TANG

JACKY TANG — Wed, 17 Jun 2020 07:33:00 +0000

In reply to JACKY TANG.

This type of dvd player always the platic gear wore out, need to replace it, becos i have done so many this type of dvd repairs before, the cambridge audio always have the tranformer problem due to quality built, recently i just repaired one with tranformer problem..hahaha..

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By: JACKY TANG

JACKY TANG — Wed, 17 Jun 2020 07:29:27 +0000

In reply to Waleed Rishmawi.

Hi brother, may i know the tranformer primary, the brown n blue colour were 230 voltage, and the black n blue colour cables were 110 voltage? Not the black colour cable was neutral(0 v) , and the blue n brown colour cables were live? Thanks

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By: Parasuraman S

Parasuraman S — Wed, 17 Jun 2020 06:11:21 +0000

In reply to Albert van Bemmelen.

Because of mass production, there will be some percentage of inherent defects which ultimately fail in due course of time. Anyhow, for us, electronic enthusiasts, such 'contribution' from the manufacturers are welcome! (LOL)

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By: Humberto

Humberto — Wed, 17 Jun 2020 03:02:55 +0000

I´ve enjoyed a lot reading how you fixed this DVD Player.

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