Hello,

Unfortunately last night my 120V stereo was plugged into a 220V socket directly.
(We're just about talking again).

The stereo now ceases to function more or less
- Radio, tape player, amplifier and lights not working
- Only the record platter turns.
There was a burning chemical smell afterwards.

I've looked inside today and cannot see any fuses and unfortunately the electronics looks fairly complicated
(I've fairly limited experience).

What I did notice was that the transformer had some hardened fluid both outside and inside. (See photos attached).
My googling has some people saying that this can happen naturally and others saying there is an issue.

Can anyone advise based on the photos if the transformer is fried (literally) and/or if there's an easy way to test it?
~ I've a multimeter but am a bit nervous dealing with power issues/transformers.

- It's labelled as AC-159C
- There seems to be 2 input wires (white) and 5 output (2 x red, 1 x black, 1 x green and 1 x yellow)
- I've been unable to find any specifications on it or the stereo so I'm not sure what the voltages should be.

Thank you

 

That is just varnish. It is normal for it to be slopped on, on cheap transformers.

 

last night my 120V stereo was plugged into a 220V socket directly.

Don't 120V sockets normally have a different configuration that 220V sockets?

 

you should be looking at the components connected to the mains supply, and after the transformer. It is almost certainly the case that some of the power handling components have left "skid marks" on the PCB. Start wherever the mains power connects and then also where the secondary of that transformer connects.

 

Don't 120V sockets normally have a different configuration that 220V sockets?

Yes, but unfortunately the offender had the ability to both find and use my plug adaptor.

 

you should be looking at the components connected to the mains supply, and after the transformer. It is almost certainly the case that some of the power handling components have left "skid marks" on the PCB. Start wherever the mains power connects and then also where the secondary of that transformer connects.

Thanks for responding Yaakov. I was hoping for an easy fix (just replace the transformer). The electrics inside is super compacted into a small space, I guess I've no choice but to plough ahead. Thanks again.

 

Thanks for responding Yaakov. I was hoping for an easy fix (just replace the transformer). The electrics inside is super compacted into a small space, I guess I've no choice but to plough ahead. Thanks again.

You can test the transformer, but it seems the least likely failure point.

 

Thanks for responding Yaakov. I was hoping for an easy fix (just replace the transformer). The electrics inside is super compacted into a small space, I guess I've no choice but to plough ahead. Thanks again.

Even if you repair the transformer this is likely the next result of a powerup.

 

Even if you repair the transformer this is likely the next result of a powerup.

Ha ha. Thanks nsaspook.

 

Thanks for responding Yaakov. I was hoping for an easy fix (just replace the transformer). The electrics inside is super compacted into a small space, I guess I've no choice but to plough ahead. Thanks again.

In my experience such a serious misuse that led to obvious smells of burning and so on, is very likely to lead to easy to spot damage.

It could well be that the failed component is the only failed component, so carefully inspect the board (ensuring its disconnected from the wall power) and note anything that looks discolored, cracked, areas of the PCB that looked discolored etc.

That would be my first step, sometimes you do need to look carefully and closely, the failed component(s) are often not obvious unless you shine a bright light and scrutinize closely. If there was a chemical/burning smell I'd very much expect to see evidence of heat or damage somewhere.

 

You can test the transformer, but it seems the least likely failure point.

I have tested the transformer by measuring resistance across the wires (as suggested on another website).
I get a resistance value across all the input wires.
But I get an open circuit across the two white input wires.
Can I definitively say that the transformer is faulty?

 

I have tested the transformer by measuring resistance across the wires (as suggested on another website).
I get a resistance value across all the input wires.
But I get an open circuit across the two white input wires.
Can I definitively say that the transformer is faulty?

I'd only consider that if nothing else can be found, as others say this is unlikely to be something that would fail first.

Think of this like a chain made up of different kinds of links, plastic, metal, wood and varying thicknesses, then imagine pulling the chain at each end on a machine, it will fail and it will be one specific link that fails, a similar thing applies here to the circuit, once the first thing fails its likely nothing else could fail, like in the chain analogy.

(Of course this is not guaranteed, its possible that multiple components were simply destroyed and that's why the unit now appears dead, but check for the obvious first).

 

I have tested the transformer by measuring resistance across the wires (as suggested on another website).
I get a resistance value across all the input wires.
But I get an open circuit across the two white input wires.
Can I definitively say that the transformer is faulty?

If there are only four wires and the two white wires are the secondary it could be bad. Some transformers actually have internal fuses, but... well, I wouldn't expect it to be the cause but it could be.

 

I'd only consider that if nothing else can be found, as others say this is unlikely to be something that would fail first.

Think of this like a chain made up of different kinds of links, plastic, metal, wood and varying thicknesses, then imagine pulling the chain at each end on a machine, it will fail and it will be one specific link that fails, a similar thing applies here to the circuit, once the first thing fails its likely nothing else could fail, like in the chain analogy.

(Of course this is not guaranteed, its possible that multiple components were simply destroyed and that's why the unit now appears dead, but check for the obvious first).

Thank you for both of your comments. As the main electronics are in quite a condensed inaccessible area, I'm trying to avoid disturbing that area un-necessarily...but I will go there if I have to. I would first like to rule out any transformer issues if possible.

 

If there are only four wires and the two white wires are the secondary it could be bad. Some transformers actually have internal fuses, but... well, I wouldn't expect it to be the cause but it could be.

Thanks Yaakov.
There are 7 wires linked to the transformer.
- 2 white on one side that I have assumed are the input wires ~ there is no resistance across these two wires.
- 5 wires on the other side that I have assumed are the outputs ~ There is a resistance between all of these wires.

Besides a resistance test, is measuring the voltage the only other way of testing a transformer?
(Keeping in mind that I don't have a schemata and don't know what the output voltages should be).