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Old 22nd December 2014, 01:09 AM   #1
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Default tda 7293 Blowing up when I turn on

I am sorry if there is already a topic about it though, I searched and found nothing about it.

I bought 6 of these industrial pcb to mount the amplifier with tda7293

however, as soon as I turn on the pcb on the transformer CI explodes.
I am feeding with 35vdc symmetric.

i have lost 3 ICs
then i gave up
I'm using this board:

Click the image to open in full size.

however
looking this pcb, I found that the capacitor tracks to choose which IC to use, are different ... this reversed, then I reversed the capacitor to the TDA7294 and the amplifier operated normally.


Click the image to open in full size.


but the ic are very heating up then like to know if it is normal, it also heats without any load connected.

Finally, before reversing the capacitor I tested with a power source 12v symmetrical and the IC not exploded, left about 1 minute playing softly.
I think the screen printing of the pcb is wrong, this reversed.
Anyone with experience with this IC could help me?

sorry about my bad English and thanks for the help.
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Old 22nd December 2014, 02:20 AM   #2
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The grounding sucks - in particular there's shared impedance between the signal ground (J1) and the bulk decoupler C5. Perhaps this is making the amp marginally unstable.
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Old 22nd December 2014, 10:35 AM   #3
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Can you show your power supply.

Gajanan Phadte
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Old 22nd December 2014, 03:38 PM   #4
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dumb question, but do you use a heatsink ?
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Old 22nd December 2014, 07:12 PM   #5
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yes I am using heat sink, which I do with the ground?

the IC is working perfectly after I moved the position of capacitor but this much warming, without load also heats ...
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Old 23rd December 2014, 12:40 AM   #6
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On grounding, re-route (cut and strap tracks) so that decoupling shares no common paths (tracks) with signal. C5 needs its own wire back to the power inlet, not sharing groundfill with signal ground.
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Old 23rd December 2014, 04:44 AM   #7
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You have grounded the tab... to where.

Gajanan Phadte
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Old 26th December 2014, 03:01 AM   #8
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Quote:
Originally Posted by gmphadte View Post
You have grounded the tab... to where.

Gajanan Phadte

you talk about the ground, the 4rd wire? or the center tap, of the transformer?

+V+ 35v
-v 35v
0v
ground

i am not using ground to earth
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Old 26th December 2014, 11:46 AM   #9
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The tab is connected to -Vs and that is a signal ground.

Gajanan Phadte
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