Sony TA F240 blowing fuses

joshvegas · 30th December 2007, 09:20 PM

I have an old Sony TA F240 Amplifier which stopped working.

The Amp fails to switch on so i whipped the cover off and had a poke around the power supply and i noticed the slow blow or time delay fuse was blown so i put in a replacement (T2.5A 250V)I also noticed that the little pcb it was mounted on had come loose from transformer itself and soldered that back up aswell. Feeling fairly pleased with myself i screwed it all back together switched it on and was rewarded with a flash of light and a newly blown fuse. At this point the internet and guess work fails me so...

My question is this what could be causing this and how do i fix it?

Other than fixing and modifying guitars this is my first time. be gentle.

Cheers guys.

sinistersoulz · 14th April 2008, 07:24 PM

Did you sort this? I have exactly the same amp and I love it but it blew on sunday the 13th =[ it smoked so i took the plug out. but it wont turn back on just like yours. you say there is some kind of internal fuse and something else? could i have a dummies guide to this please?

btw this is mine and was wondering if you could point out aswell to just where what your describing is?
please add me on msn at menacingvandals@hotmail.com

jaycee · 14th April 2008, 09:03 PM

Chances are one or more output transistors have blown.

This needs someone who knows what they're doing to repair - find a good repair shop.

sinistersoulz · 15th April 2008, 12:01 PM

Thank you. Reckon it will be repairable? cheap fix or expensive?

Mooly · 15th April 2008, 12:25 PM

Nothings cheap to fix these days. As Jaycee says you need someone who knows what they are doing. Using unsuitable substitute semiconductors is a recipe for disaster, it might be O.K. for short while only, plus there could be underlying reason for failure in first place. But having said that if you can come up with circuit

anything is possible

even fixing it.
Regards Karl

sinistersoulz · 15th April 2008, 02:54 PM

The cause I would have though would be where I was rewiring my speakers at the time that a wire went were it wasnt supposed to and being the tard that i am hadnt turned the amp off and had left it at a high volume level.

joshvegas · 17th April 2008, 12:14 AM

Hey Guys totally forgot about this post!

the red circle is the board and the green is where the anti surge fuse is, it will switch on with a new fuse but then blows again and some of the contacts on the board are knackered could this be the problem?.

I'm not that bothered i have another amp but it would be nice to have one for my kitcehn for rock and roll cooking!

sinistersoulz · 19th April 2008, 03:31 PM

Thanks for the reply josh

I miss my loud music =[

jaycee · 25th April 2008, 12:02 AM

Sinistersoulz, you will definitely have blown the output transistors in the amp, and possibly more parts. Shorting the output is probably the worst thing you can do to a power amplifier, so the damage is likely to be extensive and not cost effective to fix.

joshvegas, if the fuse blows its because theres a fault somewhere else in the circuit. "Some of the contacts are knackered", which ones? Why did the amp pop its fuse in the first place?

joshvegas · 25th April 2008, 08:08 PM

I have no idea why it blew it just did!

on the indicated board some of the soldering joints look decidedly shaky! particularly the ones connecting the board to the transformer.

Sorry I can't be more specific The amp is at my parents at the moment!

Thanks for taking the time to reply to a total dunce!

30th December 2007, 09:20 PM	#1
joshvegas diyAudio Member Join Date: Dec 2007	Sony TA F240 blowing fuses I have an old Sony TA F240 Amplifier which stopped working. The Amp fails to switch on so i whipped the cover off and had a poke around the power supply and i noticed the slow blow or time delay fuse was blown so i put in a replacement (T2.5A 250V)I also noticed that the little pcb it was mounted on had come loose from transformer itself and soldered that back up aswell. Feeling fairly pleased with myself i screwed it all back together switched it on and was rewarded with a flash of light and a newly blown fuse. At this point the internet and guess work fails me so... My question is this what could be causing this and how do i fix it? Other than fixing and modifying guitars this is my first time. be gentle. Cheers guys.

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14th April 2008, 07:24 PM	#2
sinistersoulz diyAudio Member Join Date: Apr 2008	Did you sort this? I have exactly the same amp and I love it but it blew on sunday the 13th =[ it smoked so i took the plug out. but it wont turn back on just like yours. you say there is some kind of internal fuse and something else? could i have a dummies guide to this please? btw this is mine and was wondering if you could point out aswell to just where what your describing is? please add me on msn at menacingvandals@hotmail.com

14th April 2008, 09:03 PM	#3
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	Chances are one or more output transistors have blown. This needs someone who knows what they're doing to repair - find a good repair shop.

15th April 2008, 12:01 PM	#4
sinistersoulz diyAudio Member Join Date: Apr 2008	Thank you. Reckon it will be repairable? cheap fix or expensive?

15th April 2008, 12:25 PM	#5
Mooly diyAudio Member Join Date: Sep 2007	Nothings cheap to fix these days. As Jaycee says you need someone who knows what they are doing. Using unsuitable substitute semiconductors is a recipe for disaster, it might be O.K. for short while only, plus there could be underlying reason for failure in first place. But having said that if you can come up with circuit anything is possible even fixing it. Regards Karl

15th April 2008, 02:54 PM	#6
sinistersoulz diyAudio Member Join Date: Apr 2008	The cause I would have though would be where I was rewiring my speakers at the time that a wire went were it wasnt supposed to and being the tard that i am hadnt turned the amp off and had left it at a high volume level.

17th April 2008, 12:14 AM	#7
joshvegas diyAudio Member Join Date: Dec 2007	Hey Guys totally forgot about this post! the red circle is the board and the green is where the anti surge fuse is, it will switch on with a new fuse but then blows again and some of the contacts on the board are knackered could this be the problem?. I'm not that bothered i have another amp but it would be nice to have one for my kitcehn for rock and roll cooking!

19th April 2008, 03:31 PM	#8
sinistersoulz diyAudio Member Join Date: Apr 2008	Thanks for the reply josh I miss my loud music =[

25th April 2008, 12:02 AM	#9
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	Sinistersoulz, you will definitely have blown the output transistors in the amp, and possibly more parts. Shorting the output is probably the worst thing you can do to a power amplifier, so the damage is likely to be extensive and not cost effective to fix. joshvegas, if the fuse blows its because theres a fault somewhere else in the circuit. "Some of the contacts are knackered", which ones? Why did the amp pop its fuse in the first place?

25th April 2008, 08:08 PM	#10
joshvegas diyAudio Member Join Date: Dec 2007	I have no idea why it blew it just did! on the indicated board some of the soldering joints look decidedly shaky! particularly the ones connecting the board to the transformer. Sorry I can't be more specific The amp is at my parents at the moment! Thanks for taking the time to reply to a total dunce!

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