Sonic Impact T-amp - channel gone missing - diyAudio
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Old 20th March 2007, 03:50 AM   #1
lampman is offline lampman  Australia
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Question 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 ! )
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Old 20th March 2007, 09:24 AM   #2
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Why not get one one M. Mardis Trends from
http://www.audiomagus.com/? Great amp.
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Old 20th March 2007, 11:27 AM   #3
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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....
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Old 20th March 2007, 04:49 PM   #4
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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.
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Old 22nd March 2007, 04:33 AM   #5
lampman is offline lampman  Australia
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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.
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Old 25th March 2007, 01:23 PM   #6
lampman is offline lampman  Australia
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Default Nudie pic

Pic of my amp undressed - it all seems fine to me !
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Old 25th March 2007, 02:52 PM   #7
lampman is offline lampman  Australia
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Censored version...
Attached Images
File Type: jpg si5066_pcb.jpg (99.3 KB, 140 views)
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Old 25th March 2007, 02:52 PM   #8
lampman is offline lampman  Australia
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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 ?
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Old 25th March 2007, 03:47 PM   #9
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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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Old 25th March 2007, 10:35 PM   #10
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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
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