Transformer expert needed.

nairod156 · 13th January 2009, 08:15 PM

Hi All,
I have a Musical Fidelity B1 integrated amp which has a burnt out toroidal transformer. My problem is that I know very little about electronics apart from applying common sense, which is how I diagnosed the problem.
What I need help with is with buying a replacement. Looking online there are all different ratings - how do I work out which one I need. MF aren't interested in helping with old gear and I haven't managed to find a company that will try to help.
So this is my last resort before giving up on my old amp which would be very sad as it has served me well.
Hope someone out there can help.
Many thanks,
Ian

jaycee · 13th January 2009, 08:51 PM

If you know what output voltage is needed, I would guage the VA spec of the original by size. Compare it to the size of available transformers.

How have you come to the conclusion that the transformer is dead btw? The best thing to do would be to continuity test the primaries (side that connects to the mains) - if they are open circuit, then the transformer is stuffed.

wg_ski · 13th January 2009, 08:57 PM

Start with the obvious -

How many watts is the amp, how big is the existing trafo (dimensions), what is the rated current draw on the back panel?
This will give clues as to VA rating.

What's the secondary voltage supposed to be? Component volatge ratings and power output spec can help calculate if it's not labeled on the pcb for example.

The not so obvious - see if there is some sort of thermal cutout that is open. Sometimes the non-resettable ones are not permanently wired in series with the primary and have dedicated lead outs. You could bypass it if that turns out to be the problem.

MondyT · 13th January 2009, 10:48 PM

Hi Ian

Do you have any details or part numbers/serial numbers etc on the transformer label?

Maybe a photo could help?

Cheers
Ray

hifimaker · 13th January 2009, 11:35 PM

Testing the continuity of the primary and secondary and report back to the forum as has been suggested would be helpful, along with a pic.

If the transformer is indeed shorted inside... Also consider contacting Musical Fidelity, they might actually help you with the specs. Let them know you are a electronics tech trying to fix the amp and need the trafo specs.

13th January 2009, 08:15 PM	#1
nairod156 diyAudio Member Join Date: May 2008	Transformer expert needed. Hi All, I have a Musical Fidelity B1 integrated amp which has a burnt out toroidal transformer. My problem is that I know very little about electronics apart from applying common sense, which is how I diagnosed the problem. What I need help with is with buying a replacement. Looking online there are all different ratings - how do I work out which one I need. MF aren't interested in helping with old gear and I haven't managed to find a company that will try to help. So this is my last resort before giving up on my old amp which would be very sad as it has served me well. Hope someone out there can help. Many thanks, Ian

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13th January 2009, 08:51 PM	#2
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	If you know what output voltage is needed, I would guage the VA spec of the original by size. Compare it to the size of available transformers. How have you come to the conclusion that the transformer is dead btw? The best thing to do would be to continuity test the primaries (side that connects to the mains) - if they are open circuit, then the transformer is stuffed.

13th January 2009, 08:57 PM	#3
wg_ski diyAudio Member Join Date: Oct 2007	Start with the obvious - How many watts is the amp, how big is the existing trafo (dimensions), what is the rated current draw on the back panel? This will give clues as to VA rating. What's the secondary voltage supposed to be? Component volatge ratings and power output spec can help calculate if it's not labeled on the pcb for example. The not so obvious - see if there is some sort of thermal cutout that is open. Sometimes the non-resettable ones are not permanently wired in series with the primary and have dedicated lead outs. You could bypass it if that turns out to be the problem.

13th January 2009, 10:48 PM	#4
MondyT diyAudio Member Join Date: Dec 2008	Hi Ian Do you have any details or part numbers/serial numbers etc on the transformer label? Maybe a photo could help? Cheers Ray

13th January 2009, 11:35 PM	#5
hifimaker diyAudio Member Join Date: Oct 2003 Location: San Jose	Testing the continuity of the primary and secondary and report back to the forum as has been suggested would be helpful, along with a pic. If the transformer is indeed shorted inside... Also consider contacting Musical Fidelity, they might actually help you with the specs. Let them know you are a electronics tech trying to fix the amp and need the trafo specs.

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