Seek toroid help

eddog · 29th March 2006, 08:08 PM

I have acquired a very large toroid out of a Crown K2 amp and am trying to determine the output voltages when connected to 120v mains. I have a variable AC power supply so I thought I would bring the voltage up slowly and test the outputs. This doesnt seem to work as my power supply keeps popping it's 5 amp protection. I know you need soft start circuits on large toroids, isnt raising the voltage slowly simulating a soft start?

lndm · 29th March 2006, 09:58 PM

It would need a soft start when there was a large filter cap connected somewhere after it. Are you using mains frequency AC? are you on the primary and is your secondary open circuit?

A primary is really a large inductor. If for some reason this is upsetting your ps, you might shunt your secondary with a resistance.

I like to do initial winding testing with a signal generator (prefer that it can handle a short just in case) and a cro (a dmm will do).

pinkmouse · 29th March 2006, 11:12 PM

Arghh, a K2 Arghhhhhh!

These have to be one of the least reliable amps I have ever worked with, and you've guessed it, one of the failure modes was the traffo secondaries shorting. I was given three dead ones, and the only things worth salvaging were the heatsink temperature sensors...

If yours has this fault, sorry.

eddog · 30th March 2006, 01:24 PM

Thanks Pinkmouse and Indm, shorted secondaries it is. The owner of the amp said it fell off his truck one night and never worked after that. I thought Crown was supposed to be such roadworthy gear? Oh well the heatsinks will look good on my chipamp and I bet the 6800uf caps will come in handy somewhere down the road. Actually I think I might use the old case for the chip amp, you know, make it look like I've got a real expensive amp!

pinkmouse · 30th March 2006, 05:10 PM

If it's any consolation, the Powerbase series are even worse.

29th March 2006, 08:08 PM	#1
eddog diyAudio Member Join Date: Nov 2004 Location: Small Town in Minnesota	Seek toroid help I have acquired a very large toroid out of a Crown K2 amp and am trying to determine the output voltages when connected to 120v mains. I have a variable AC power supply so I thought I would bring the voltage up slowly and test the outputs. This doesnt seem to work as my power supply keeps popping it's 5 amp protection. I know you need soft start circuits on large toroids, isnt raising the voltage slowly simulating a soft start?

29th March 2006, 11:12 PM	#3
pinkmouse diyAudio Moderator Join Date: Apr 2002 Location: Chatham, England	Arghh, a K2 Arghhhhhh! These have to be one of the least reliable amps I have ever worked with, and you've guessed it, one of the failure modes was the traffo secondaries shorting. I was given three dead ones, and the only things worth salvaging were the heatsink temperature sensors... If yours has this fault, sorry. __________________ Al I conceive of nothing, in religion, science or philosophy, that is more than the proper thing to wear, for a while. Charles Fort

30th March 2006, 05:10 PM	#5
pinkmouse diyAudio Moderator Join Date: Apr 2002 Location: Chatham, England	If it's any consolation, the Powerbase series are even worse. __________________ Al I conceive of nothing, in religion, science or philosophy, that is more than the proper thing to wear, for a while. Charles Fort

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29th March 2006, 09:58 PM	#2
lndm diyAudio Member Join Date: Mar 2006 Location: nsw	It would need a soft start when there was a large filter cap connected somewhere after it. Are you using mains frequency AC? are you on the primary and is your secondary open circuit? A primary is really a large inductor. If for some reason this is upsetting your ps, you might shunt your secondary with a resistance. I like to do initial winding testing with a signal generator (prefer that it can handle a short just in case) and a cro (a dmm will do).

30th March 2006, 01:24 PM	#4
eddog diyAudio Member Join Date: Nov 2004 Location: Small Town in Minnesota	Thanks Pinkmouse and Indm, shorted secondaries it is. The owner of the amp said it fell off his truck one night and never worked after that. I thought Crown was supposed to be such roadworthy gear? Oh well the heatsinks will look good on my chipamp and I bet the 6800uf caps will come in handy somewhere down the road. Actually I think I might use the old case for the chip amp, you know, make it look like I've got a real expensive amp!

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