Faulty torodial transformer - Looking for replacement and answer

[blueluke234]

Hello everyone.
We own a OWI CRS-101 Infrared Wireless Microphone System and the system would get very hot and we presume overheat the board causing the system to cut sound. We have been back and forth with the Manufacturer, OWI and their technicians believe that the torodial transformer is over heating. The device is 12 years old and they said the insulation could be faulty. Would love to hear your opinions on this analysis so far.

After opening up the device and taking a look at the transformer, it has very unique outputs making it hard to find. Has anyone been able to find one that matches this? Or somewhere that it could be custom ordered?

Thanks
N

 

[gophert]

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[Diver300]

It's a good find from gophert. The remaining issue with specifying a new transformer is that the current rating could be different for each output.

A transformer will usually last almost indefinitely. 12 years isn't significant. If something has caused the transformer to short some of the windings it will get hot, but there could also be an external short. If possible, I would suggest disconnecting the low voltage connections and leaving the transformer connected to the mains for an hour or so to see if it gets hot. If it's no more than warm after an hour, and the output voltages are about right, it's working fine. With no load, I would expect all the output voltages to be around 10% higher than the numbers printed on the transformer.

 

[Nigel Goodwin]

There used to be countless adverts in the electronics magazines for custom wound toroids, so well done Gophert for finding a source now.

However, I'm with Diver300 in that it sounds VERY, VERY unlikely to be the transformer - this isn't something transformers normally (or ever) do.

But as the OP is in contact with the manufacturer and technicians, why not simply order a replacement transformer from them if he really wants to try one. I'm pretty dubious though about 'technicians', as it sounds like a crazy component to blame.

 

[atferrari]

The technicians "believe" but did not put their actual hands on the board.

Sorry, but that is an expensive way of trying to repair something.

 

[MaxHeadRoom78]

One good supplier that makes up custom Toroids is Antek
Max.

 

[gophert]

The materials of construction and methods of construction of the magnetizable core plays a huge role in the efficiency of the transformer (I.e how much power is lost as heat during operation). If it has ferrosilicon steel laminations, waster / humidity can damage the insulation between plates and cause it to run hot. If it is epoxy-impregnated iron powder, a physical crack in the epoxy binder (impact or stress cracking) or crumbling (poor epoxy mixing or curing) can cause an efficiency loss. Laminations were the only option, 15-years ago and more but the epoxy-binder with iron powder other magnetically-active metal powder (senDust, CoolMu, ...) are becoming more popular for large toroidal cores for these transformers. Note- the epoxy/iron cores were the standard for ATX-style power supplies for nearly 30-years but those are about 1" toroidal.

final note - these mentioned failure modes are rare vs other high-current draw failures associated with the electronics (or even a metal fragment causing a short on the board).

 

[MaxHeadRoom78]

In some cases the overheating of Toroidal transformer can be due to a mechanical mounting connection between the centre mounting assembly and the outer chassis or frame, essentially causing a shorted-turn.
Max.

 

[tvtech]

In some cases the overheating of Toroidal transformer can be due to a mechanical mounting connection between the centre mounting assembly and the outer chassis or frame, essentially causing a shorted-turn.
Max.

In other words "don't put a bolt through the middle of a toroidal transformer to hold it in place"

 

[MaxHeadRoom78]

No, a bolt is fine, with the customary clamp disc, it when there is a connection between this bolt/clamp and the bottom or rest of the chassis from the outside
I have seen some place a U-shaped bracket that has been used to clamp the transformer and the sides went down to the chassis surface, effecting a shorted turn.
Max

 

[schmitt trigger]

Toroidal transformers are not cheap.
A simple test before you spend some hard earned cash on a replacement, would be to disconnect all the secondary wires and see if the transformer self-heats without any load.