My Aksa (original) has given up

mingdao · 09:56 PM

Hi all. Hi Hugh!

I used to lurk in these forums in late nineties. Then work and family took over. My original account is long lost, but some things remain from that age including couple of amps that I had built with my own hands.

One of them, which was built in 2001, if I recall correctly, is Aksa original amp.

One channel gave up and no longer works. I suspect blown transistor in the first stage, since it gets smoking hot (circled red in the pic). I've actually burned my fingers pretty bad.

I do not have any plans for the thing, or a part list.
I am contemplating whether it is possible to revive it without a major effort.
Any ideas what may wrong and what is the part that I need.
Does it have to be matched pair (L/R)?
Many thanks.

Bigun · 10:48 PM

Is that even an original AKSA board or a DIY copy ? It looks like it's caked in dirt and dust and really should be cleaned up or it's just a bad photo.

Blown transistors usually don't run hot, either because they are open circuit (no current) or dead short (no voltage), the problem is possibly elsewhere. Are both fuses OK? Is there a voltage at the output ? Can you measure any of the operating points - voltages around the circuit.

AKSA · 29th July 2018, 11:01 PM

That's an original AKSA, Bigun! Thank you for your post.

Mingdao, if the voltage amp is running hot it likely means that the npn output device, C1302, is blown. Measure the voltage from the positive rail to the emitter on that transistor; if it is less than 1V, it's your man. Replace it and the amp will sing again!

Hugh

saf · 2nd August 2018, 10:08 AM

I have to say, without wanting to be offensive, that is probably the dirtiest ugliest looking AKSA i have ever seen.... Clean that up Dude !!!Please !

AKSA · 2nd August 2018, 10:22 AM

The man speaks the truth....... naughty, naughty. Your amp looks like a porn star.......
Start with compressed air, then start with isopropanol, which does not leave a stain.

I would suggest you take it from the heatsink too to remove the dust around the output stage. I have a feeling the npn output device (2SC5200) is blown, so you might need to change it, or both in fact, the pnp as well. Can't hurt!

Cheers,

Hugh

Bigun · 18th September 2018, 01:54 AM

Quote:

Originally Posted by AKSA

The man speaks the truth....... naughty, naughty. Your amp looks like a porn star.......
Start with compressed air, then start with isopropanol...

That’s no way to treat an actress!

AKSA · 18th September 2018, 04:30 AM

True enough...... but in that industry, Gareth, she might quite like it?

Hugh

29th July 2018, 09:39 PM	#1
mingdao diyAudio Member Join Date: Jul 2018	My Aksa (original) has given up Hi all. Hi Hugh! I used to lurk in these forums in late nineties. Then work and family took over. My original account is long lost, but some things remain from that age including couple of amps that I had built with my own hands. One of them, which was built in 2001, if I recall correctly, is Aksa original amp. One channel gave up and no longer works. I suspect blown transistor in the first stage, since it gets smoking hot (circled red in the pic). I've actually burned my fingers pretty bad. I do not have any plans for the thing, or a part list. I am contemplating whether it is possible to revive it without a major effort. Any ideas what may wrong and what is the part that I need. Does it have to be matched pair (L/R)? Many thanks. Last edited by mingdao; 29th July 2018 at 09:56 PM. Reason: Misspelling

29th July 2018, 10:46 PM	#2
Bigun diyAudio Member Join Date: Jan 2009 Location: Waterloo, ON or Herefordshire UK	Is that even an original AKSA board or a DIY copy ? It looks like it's caked in dirt and dust and really should be cleaned up or it's just a bad photo. Blown transistors usually don't run hot, either because they are open circuit (no current) or dead short (no voltage), the problem is possibly elsewhere. Are both fuses OK? Is there a voltage at the output ? Can you measure any of the operating points - voltages around the circuit. __________________ "The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed." Robert M Pirsig. Last edited by Bigun; 29th July 2018 at 10:48 PM.

29th July 2018, 11:01 PM	#3
AKSA diyAudio Member Join Date: Sep 2001 Location: Melbourne, Australia	That's an original AKSA, Bigun! Thank you for your post. Mingdao, if the voltage amp is running hot it likely means that the npn output device, C1302, is blown. Measure the voltage from the positive rail to the emitter on that transistor; if it is less than 1V, it's your man. Replace it and the amp will sing again! Hugh __________________ Aspen Amplifiers P/L (Australia) www.aksaonline.com

2nd August 2018, 10:22 AM	#5
AKSA diyAudio Member Join Date: Sep 2001 Location: Melbourne, Australia	The man speaks the truth....... naughty, naughty. Your amp looks like a porn star....... Start with compressed air, then start with isopropanol, which does not leave a stain. I would suggest you take it from the heatsink too to remove the dust around the output stage. I have a feeling the npn output device (2SC5200) is blown, so you might need to change it, or both in fact, the pnp as well. Can't hurt! Cheers, Hugh __________________ Aspen Amplifiers P/L (Australia) www.aksaonline.com

18th September 2018, 04:30 AM	#7
AKSA diyAudio Member Join Date: Sep 2001 Location: Melbourne, Australia	True enough...... but in that industry, Gareth, she might quite like it? Hugh __________________ Aspen Amplifiers P/L (Australia) www.aksaonline.com

2nd August 2018, 10:08 AM	#4
saf diyAudio Member Join Date: Sep 2009 Location: Porto	I have to say, without wanting to be offensive, that is probably the dirtiest ugliest looking AKSA i have ever seen.... Clean that up Dude !!!Please !

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