Sonic Impact T-amp - channel gone missing

lampman · 20th March 2007, 03:50 AM

After a few months of working perfectly, one of the channels stopped working.

Thought it had fixed itself, but it cut out again after a few minutes (after warming up ?).

It's hooked up to my PC soundcard, connected to 4 ohm speakers and I'm powering it from a 9v transformer.

I'm clueless about amps, have only tried swapping the speakers and leads around to no effect.

Is it worthwhile having a look inside the box ?

Thanks for any suggestions...

(one suggestion might be buy another....SI have offered to repair it for a cost of $59 + return shipping ! )

shepperd · 20th March 2007, 09:24 AM

Why not get one one M. Mardis Trends from
http://www.audiomagus.com/? Great amp.

audiovista · 20th March 2007, 11:27 AM

It could be a thermal shutdown due to overheating. Try adding a small heatsink to the amplifier chip. You can easily make one from a thin piece of aluminum or copper and then glue it on top (very thin layer of glue). Who knows, may help....

Sonusthree · 20th March 2007, 04:49 PM

Hi,
Does it usually work when you switch on from cold and then does it shut down? This MIGHT be the thermal protection.

Have you tried gently tapping the case while switched on. Sometimes it is possible to have a bad (dry) solder joint that is affected by thermal expansion.

I suppose that you may as well have a go at fixing it yourself with some advice from this forum. Take advice first though!! There are a few simple things that you could look at yourself with a good eye, soldering iron, and a multimeter! Fancy a challenge? A schematic would help also (circuit diagram).

Martin.

lampman · 22nd March 2007, 04:33 AM

Hi, thanks all for replying;

I tried restarting it from cold but now am consistently just getting one channel again.

Have yet to look inside the box (need a smaller screwdriver), but doubt I can fix it unless its something really obvious.

The upgrade to the SI was like getting a pair of new specs (!), so I'd be quite interested in getting another t-amp like the Trends one. (But at $130 is it 4 times better than the SI ?)

Anyway it's back to mono for me, will let you know if I have any success.

lampman · 25th March 2007, 01:23 PM

Pic of my amp undressed - it all seems fine to me !

lampman · 25th March 2007, 02:52 PM

Censored version...

lampman · 25th March 2007, 02:52 PM

Hmmmm....

Just put the box back together, and where previously only the left channel had been working, now it was the right channel that was ok, and the left could be heard at much lower volume, which faded away completely after about 30 seconds.

At least my speakers are getting evenly used.

Does it matter that the power supply is rated 500 mAmp ?

audiovista · 25th March 2007, 03:47 PM

Sounds like you may have problems with connections. Inspect connections between PCB and inputs/outputs. Ohmmeter will help, but poor connection can often be visually detected.

Keep us posted.

Lostcause · 25th March 2007, 10:35 PM

Quote:

Originally posted by lampman
Hmmmm....

Just put the box back together, and where previously only the left channel had been working, now it was the right channel that was ok, and the left could be heard at much lower volume, which faded away completely after about 30 seconds.

At least my speakers are getting evenly used.

Does it matter that the power supply is rated 500 mAmp ?

Difficult to tell but C11 looks suspect...
Even though, you need more than half an amp at 12V to keep it sweet..... try a more powerful PSU

20th March 2007, 03:50 AM	#1
lampman diyAudio Member Join Date: Mar 2007	Sonic Impact T-amp - channel gone missing After a few months of working perfectly, one of the channels stopped working. Thought it had fixed itself, but it cut out again after a few minutes (after warming up ?). It's hooked up to my PC soundcard, connected to 4 ohm speakers and I'm powering it from a 9v transformer. I'm clueless about amps, have only tried swapping the speakers and leads around to no effect. Is it worthwhile having a look inside the box ? Thanks for any suggestions... (one suggestion might be buy another....SI have offered to repair it for a cost of $59 + return shipping ! )

25th March 2007, 01:23 PM	#6
lampman diyAudio Member Join Date: Mar 2007	Nudie pic Pic of my amp undressed - it all seems fine to me !

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20th March 2007, 09:24 AM	#2
shepperd diyAudio Member Join Date: Sep 2006	Why not get one one M. Mardis Trends from http://www.audiomagus.com/? Great amp.

20th March 2007, 11:27 AM	#3
audiovista diyAudio Member Join Date: Nov 2006	It could be a thermal shutdown due to overheating. Try adding a small heatsink to the amplifier chip. You can easily make one from a thin piece of aluminum or copper and then glue it on top (very thin layer of glue). Who knows, may help....

20th March 2007, 04:49 PM	#4
Sonusthree diyAudio Member Join Date: Dec 2005 Location: Brighton,UK	Hi, Does it usually work when you switch on from cold and then does it shut down? This MIGHT be the thermal protection. Have you tried gently tapping the case while switched on. Sometimes it is possible to have a bad (dry) solder joint that is affected by thermal expansion. I suppose that you may as well have a go at fixing it yourself with some advice from this forum. Take advice first though!! There are a few simple things that you could look at yourself with a good eye, soldering iron, and a multimeter! Fancy a challenge? A schematic would help also (circuit diagram). Martin.

22nd March 2007, 04:33 AM	#5
lampman diyAudio Member Join Date: Mar 2007	Hi, thanks all for replying; I tried restarting it from cold but now am consistently just getting one channel again. Have yet to look inside the box (need a smaller screwdriver), but doubt I can fix it unless its something really obvious. The upgrade to the SI was like getting a pair of new specs (!), so I'd be quite interested in getting another t-amp like the Trends one. (But at $130 is it 4 times better than the SI ?) Anyway it's back to mono for me, will let you know if I have any success.

25th March 2007, 02:52 PM	#8
lampman diyAudio Member Join Date: Mar 2007	Hmmmm.... Just put the box back together, and where previously only the left channel had been working, now it was the right channel that was ok, and the left could be heard at much lower volume, which faded away completely after about 30 seconds. At least my speakers are getting evenly used. Does it matter that the power supply is rated 500 mAmp ?

25th March 2007, 03:47 PM	#9
audiovista diyAudio Member Join Date: Nov 2006	Sounds like you may have problems with connections. Inspect connections between PCB and inputs/outputs. Ohmmeter will help, but poor connection can often be visually detected. Keep us posted.

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