Transformer fault finding

TerryS · 20th November 2003, 03:52 PM

Hi, I am afraid I am one of those keen individuals with a limited knowledge of electronics! I have a Wharfedale Stereo Hi-Fi (Model S-990) that has given up the ghost. I have a feeling that it may be the transformer that has packed in but are not sure how to check whether it is.
Can anyone advise me on carrying out the checks please? If it is the transformer & I cannot get a direct replacement how do I go about getting one similar and as the connections may not be completely the same, connect it up?

Thanks in advance for any help you may give. (remember, don't be too strong on technical knowledge knowing my limitations!)

Regards
Terry

richie00boy · 20th November 2003, 06:19 PM

Why do you think the transformer has gone? More likely to be a fuse or other component.

You can check the thermal fuse by measuring the winding resistances. If any of them are open-circuit, there's your problem.

TerryS · 21st November 2003, 09:29 AM

I have tried the fuses and they all appear to be ok. I mentioned that I had a very basic knowledge of electronics but a willingness to learn! How do I check for the open circuits you describe? What do I set the digital multimeter to. Sorry to be a pain but neverthless appreciate your assistance.

Regards
Terry

richie00boy · 21st November 2003, 01:38 PM

Set the meter to ohms/resistance.

Measure across connections where the wire appears to be the same thickness - this is most likely to be a continuous winding and so should measure less than 100 ohms. It's possible that the secondary may have 3 connections - 2 ends and a middle. It's also possible that there may be two secondary windings.

Obviously, this is all with NO power connected.

TerryS · 21st November 2003, 02:06 PM

Much oblidged. I am currently at work so will check it out tonight. If it is a transformer failure & I cannot get an original match, what should I do to find a comparable replacement?

Thanks for your indulgence.
Regards
Terry

richie00boy · 21st November 2003, 07:26 PM

First, contact Wharfedale, they may be able to sell you a part. If they won't sell you one, see if you can find out what voltage(s) it puts out and at what current rating(s).

Then the mission is on to try and source a replacement... May not be that easy. You may have to bodge a toroidal transformer in the case somehow.

Also, give CPC a call or email. They carry a lot of spares for consumer goods.

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20th November 2003, 06:19 PM	#2
richie00boy Did it Himself diyAudio Member Join Date: Nov 2003 Location: Gloucestershire, England, UK	Why do you think the transformer has gone? More likely to be a fuse or other component. You can check the thermal fuse by measuring the winding resistances. If any of them are open-circuit, there's your problem.

21st November 2003, 09:29 AM	#3
TerryS diyAudio Member Join Date: Nov 2003 Location: Scotland	I have tried the fuses and they all appear to be ok. I mentioned that I had a very basic knowledge of electronics but a willingness to learn! How do I check for the open circuits you describe? What do I set the digital multimeter to. Sorry to be a pain but neverthless appreciate your assistance. Regards Terry

21st November 2003, 01:38 PM	#4
richie00boy Did it Himself diyAudio Member Join Date: Nov 2003 Location: Gloucestershire, England, UK	Set the meter to ohms/resistance. Measure across connections where the wire appears to be the same thickness - this is most likely to be a continuous winding and so should measure less than 100 ohms. It's possible that the secondary may have 3 connections - 2 ends and a middle. It's also possible that there may be two secondary windings. Obviously, this is all with NO power connected.

21st November 2003, 02:06 PM	#5
TerryS diyAudio Member Join Date: Nov 2003 Location: Scotland	Much oblidged. I am currently at work so will check it out tonight. If it is a transformer failure & I cannot get an original match, what should I do to find a comparable replacement? Thanks for your indulgence. Regards Terry

21st November 2003, 07:26 PM	#6
richie00boy Did it Himself diyAudio Member Join Date: Nov 2003 Location: Gloucestershire, England, UK	First, contact Wharfedale, they may be able to sell you a part. If they won't sell you one, see if you can find out what voltage(s) it puts out and at what current rating(s). Then the mission is on to try and source a replacement... May not be that easy. You may have to bodge a toroidal transformer in the case somehow. Also, give CPC a call or email. They carry a lot of spares for consumer goods.

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