AB Amp keep blowing fuse

karlranks · 28th May 2009, 11:02 PM

I have an AB amplifier that keep blowing fuses.
Iam using the correct fuse.
It will power up then slowly the power light goes out after few second.
Thanks for some help.

Karl

slideman82 · 28th May 2009, 11:24 PM

Hi! Can you post the schematic, or its link? There's got to be a trimpot to set the quiescent current, take a look at it to know if it's all the way to right or left... probably quiescent current is too high, and be careful, if the trimpot is set at max quiescent current, the output trannies will reach the Hades in less than two
seconds...

Arcaman · 28th May 2009, 11:36 PM

Does it without any load connected ?
Have you checked if the voltage selector is in the right position, if present?

nigelwright7557 · 29th May 2009, 02:19 AM

If you havent adjusted the presets then its probably the output transistors gone.
Anything else usually doesnt take enough current to blow the fuses although a shorted capacitor might.

28th May 2009, 11:02 PM	#1
karlranks diyAudio Member Join Date: May 2009	AB Amp keep blowing fuse I have an AB amplifier that keep blowing fuses. Iam using the correct fuse. It will power up then slowly the power light goes out after few second. Thanks for some help. Karl

29th May 2009, 02:19 AM	#4
nigelwright7557 diyAudio Member Join Date: Apr 2008 Location: Carlisle, England	If you havent adjusted the presets then its probably the output transistors gone. Anything else usually doesnt take enough current to blow the fuses although a shorted capacitor might. __________________ http://www.murtonpikesystems.co.uk PCBCAD40 pcb design software.

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28th May 2009, 11:24 PM	#2
slideman82 diyAudio Member Join Date: Oct 2007	Hi! Can you post the schematic, or its link? There's got to be a trimpot to set the quiescent current, take a look at it to know if it's all the way to right or left... probably quiescent current is too high, and be careful, if the trimpot is set at max quiescent current, the output trannies will reach the Hades in less than two seconds...

28th May 2009, 11:36 PM	#3
Arcaman diyAudio Member Join Date: Mar 2009	Does it without any load connected ? Have you checked if the voltage selector is in the right position, if present?

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