Multi Voltage Transformer

[buzz0431]

How specific of voltage and amperage ratings are required for a replacement? Or what would one recommend for this? The primary and a few secondary windings blew from a voltage surge.

 

[Externet]

Welcome.
Before replacing, check the health of those components under shrink tube bulging the black wires at the right of your image by the nylon tie. Could be fuses.

 

[MaxHeadRoom78]

VERY rare you 'blow the windings' on a transformer, burn/over heat maybe, but not usual to open circuit.
Often there is a thermal fuse buried in the winding, if lucky, it can be accessed and repaired.
The winding condition appears fine in the picture.

 

[schmitt trigger]

With a multimeter, start checking the resistance values across same-colored wires. Secondary windings will be a few ohms, the primary several dozen.
If one of the winding pairs shows an open circuit, most likely a thermal fuse is open.
These thermal fuses are unfortunately buried deep within the windings.

If it is effectively open, I would think that the 11 volts outputs could be replaced with a 12 volts standard transformer. More so because your transformer is primary rated for 110 volts, whereas a very common value for replacement transformers is 117 volts. In both cases the turns ratio will be almost identical.

 

[Externet]

About 10 years ago, listening FM with my expensive vintage receiver, the lights dimmed and sound stopped. The rectifier PC board fried and smoked. After headscratching troubleshooting, found shorted windings in the transformer.
Found also that the electric utility company had a rare policy and budget to repair wherever they goofed with the electric supply.
By a very weird coincidence, ebay had those days an offer of an used power transformer for the Marantz 4400.
Complained, and they bought the transformer for me and I rebuilt the burned board.

 

[danadak]

How specific of voltage and amperage ratings are required for a replacement? Or what would one recommend for this?

Nominally one would want to replace equal or better.

The designer should have, I repeat "should have", margined the transformer with better
than needed ratings, leading one to consider lower ratings. Best way of telling that is a
before and after V, I, P readings on transformer, which you probably dont have the prior
info. Another way is to use a smaller transformer and using an IR Thermometer take
readings of power parts and the transformer and ambient to see if everything is good
to go with a lesser rated component.

Bit of a crap shoot.


Regards, Dana.

 

[MaxHeadRoom78]

How specific of voltage and amperage ratings are required for a replacement? Or what would one recommend for this? The primary and a few secondary windings blew from a voltage surge.

If you did have to replace, (unlikely) it shows by the ratings it is around 100va sized transformer. According to the secondary Va's.
But by the appearance of the windings it looks in good shape, I would dig deeper before giving up on existing one.

 

[Lightium]

What is this device that your fixing?

 

[For The Popcorn]

^^^^^ is kind of an important question.

 

[buzz0431]

This is a control board on a steam shower unit. I tested the visible fuses and the one for the 11.5v output was blown, but the primary also has an open circuit, and I highly doubt I would be able to access it without destroying everything in the process of it is a fuse buried in the winding. The unit has some led lights built in, and it has a 12v exhaust fan. It also has a the control panel with the buttons on it for operation. I do not care if the speakers no longer work, but I don't know what the center tapped 8.5v runs. Otherwise I would just probably put in a 12 v transformer and the appropriate fuses and be done with it.
The trans_out2 is where that 8.5v plugs into.

 

[buzz0431]

I did some digging and found this black thing, if I meter the winding side of it, I get approximately 6.5 ohms. What would I do to go about replacing or repairing it?

 

[MaxHeadRoom78]

Most likely if you short it out to test, the TXFR will operate OK.
Can you remove it carefully and see the make up of it.?

 

[buzz0431]

Not perfectly clear, but it says 2 amp 130°c.
I found one on digikey 106 holding temperature and 128 rated functioning temperature. Would that be what I am looking for?

 

[Nigel Goodwin]

As suggested above, temporarily short it out and test the unit - keeping a VERY close eye on how hot the transformer gets.

A common cause of heat fuse failure is a shorted turn in the transformer, and this causes it to overheat.

Assuming it works OK (and stays at a reasonable temperature) you can then get a replacement heat fuse.

 

[buzz0431]

Sounds good, thanks for all the help and advice. If I run into any other issues on this, I'll be back in touch.

 

[MaxHeadRoom78]

Personally what I do is remove, or short them out, if possible, and fit a fuse that just covers the Va of the TXFR/Load.
Which essentially what the fuse does.
Often they appear to open due to unexplainable circumstances as from then on, they appear to operate fine

 

[Nigel Goodwin]

Personally what I do is remove, or short them out, if possible, and fit a fuse that just covers the Va of the TXFR/Load.
Which essentially what the fuse does.
Often they appear to open due to unexplainable circumstances as from then on, they appear to operate fine

They usually blow for the correct reason - that the transformers gets too hot - the issue is why it got too hot.

Sometimes it's due to a faulty transformer (shorted turns as I mentioned above), or it could be something external, or as simple as the transformer was operated outside it's specifications. Often you don't know what the reason might have been, and it 'might' just have been coincidence?, but I suspect there's mostly a reason somewhere - such as poor ventilation?.

I had a big problem with a Sony amplifier, still under warranty - it was a really nice big 100W+100W RMS amplifier, and belonged to a young guy who obviously liked his music LOUD

It came in for repair, and the first thing I noticed was how light it was - it was a big chunky amplifier, and I expected some heft to it.

When I took the top off, the reason was obvious, a tiny little toroidal transformer sat on a special metal mounting bracket with lot's of empty space around it. The bracket was there to make it fit in the large space. Needless to say, the heat fuse was blown, and the connections to it were accessible on the top of the transformer - as usual though, the heat fuse wasn't replaceable. So I shorted it out, confirmed there was nothing wrong, and ordered a replacement transformer - and while waiting for it to arrive (the next day) I measured the physical size of the transformer, and compared it to those in the RS Components catalogue, which confirmed my suspicion that the transformer was massively undersized - and was only a 60W transformer.

The new one came, I fitted the transformer, did the warranty claim, and returned it to the customer. Six months or so later it came back - transformer blown again - by now it was out of warranty. I was under no doubt the reason for it's failure was due to it been too small, and contacted Sony - and after LOT'S of arguing they agreed to provide a new transformer free of charge, but wouldn't pay a warranty claim. They completely denied that the transformer was far too small, and simply said that they had had very few failures - presumably most people didn't play them loud

I was absolutely sure that the original design had called for a MUCH larger (correctly sized) transformer, and it had been replaced by a much smaller, much cheaper, one during production - but they would never admit it.

Incidentally, I kept both the old transformers, as there was nothing wrong with them.

I was hoping it might come in again, and the guy decided to replace it - and I would have kept it, and fitted a proper sized transformer from RS Components - but I never saw it again

 

[Vons Garage]

Mr. Buzz 0431:
Am I correct in seeing the mixing of high and low voltage rated cabling in the devices enclosure? And for something used in a shower? Seems scary to me. If it is possible you may want to consider moving all the high voltage stuff into a seperate box. Hopefully it is just the transformer.

 

[Nigel Goodwin]

Mr. Buzz 0431:
Am I correct in seeing the mixing of high and low voltage rated cabling in the devices enclosure? And for something used in a shower? Seems scary to me. If it is possible you may want to consider moving all the high voltage stuff into a seperate box. Hopefully it is just the transformer.

It looks to be a piece of commercial equipment, and presumably meets all required legislation - and looking at it, as far as is shown, it's unlikely to be something used 'in' a shower.

However, electric showers have mains in them anyway - and those are 'in' the shower

 

[buzz0431]

They usually blow for the correct reason - that the transformers gets too hot - the issue is why it got too hot.

Sometimes it's due to a faulty transformer (shorted turns as I mentioned above), or it could be something external, or as simple as the transformer was operated outside it's specifications. Often you don't know what the reason might have been, and it 'might' just have been coincidence?, but I suspect there's mostly a reason somewhere - such as poor ventilation?.

I had a big problem with a Sony amplifier, still under warranty - it was a really nice big 100W+100W RMS amplifier, and belonged to a young guy who obviously liked his music LOUD

It came in for repair, and the first thing I noticed was how light it was - it was a big chunky amplifier, and I expected some heft to it.

When I took the top off, the reason was obvious, a tiny little toroidal transformer sat on a special metal mounting bracket with lot's of empty space around it. The bracket was there to make it fit in the large space. Needless to say, the heat fuse was blown, and the connections to it were accessible on the top of the transformer - as usual though, the heat fuse wasn't replaceable. So I shorted it out, confirmed there was nothing wrong, and ordered a replacement transformer - and while waiting for it to arrive (the next day) I measured the physical size of the transformer, and compared it to those in the RS Components catalogue, which confirmed my suspicion that the transformer was massively undersized - and was only a 60W transformer.

The new one came, I fitted the transformer, did the warranty claim, and returned it to the customer. Six months or so later it came back - transformer blown again - by now it was out of warranty. I was under no doubt the reason for it's failure was due to it been too small, and contacted Sony - and after LOT'S of arguing they agreed to provide a new transformer free of charge, but wouldn't pay a warranty claim. They completely denied that the transformer was far too small, and simply said that they had had very few failures - presumably most people didn't play them loud

I was absolutely sure that the original design had called for a MUCH larger (correctly sized) transformer, and it had been replaced by a much smaller, much cheaper, one during production - but they would never admit it.

Incidentally, I kept both the old transformers, as there was nothing wrong with them.

I was hoping it might come in again, and the guy decided to replace it - and I would have kept it, and fitted a proper sized transformer from RS Components - but I never saw it again

I understand the person I bought this unit from had his property hooked up to a backup generator, at one point it was hooked up incorrect so there was an incorrect voltage fed to the system. They said there were some other devices around the farm that had similar issues.