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Old 11th March 2010, 09:16 PM   #1
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Default How to avoid Killing the TA2020

Hi,
I've got the Lepai TA-2020 Amplifier, but I killed the I/C twice!
I killed it by mistakenly connection the output of the amplifier to the output of another amplifier (shorting two separate amp's output together).

What mod can I do so it won't happen again? (some kind of protection circuit). I guess it can be done because in the two times I killed the TA2020, the other amp was ok and nothing happened (Vintage Rotel RX-830 Stereo Receiver).

This is really important to me. I already ordered 2pcs of TA2020 and I don't want to burn-out them.
Thanks
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Old 12th March 2010, 01:29 AM   #2
col is offline col  Australia
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The information is all there in the Lepai thread, you just have to read it all the way through.

First thing though is to remove the little orange zener diode in front of the IC. That will stop it from going into a reboot loop when a fault develops. Second, change the output inductors, the stock ones don't handle enough current and burn out easy.

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Old 12th March 2010, 05:33 AM   #3
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I know it's not your duty or something to answer my questions, but you can be sure I've read the Lepai thread twice and couldn't find an answer to this.

I've already removed the zener (first thing I did) and I've bought some Toroids to replace the current ones as you suggested, the problem is there is not enough space so I'm waiting to get a cutting tool, to cut the heatsink a bit. Anyway are you sure that's what will protect the I/C? I thought on implementing the overshoot diodes, but as said by you in the thread, some pins are all connected together so this may not work.

Any thoughts?
Thanks.
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Old 12th March 2010, 11:32 AM   #4
col is offline col  Australia
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what voltage are you running at? Check with a multimeter and make sure it is below 13.20v Anything above that and your on dangerous ground. Have you read the TA2020 data sheet?

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Old 12th March 2010, 02:53 PM   #5
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I'm using a 12V Switching Power Supply (Measured ~12v, never above 12.5v). and yes I've read the datasheet:


Quote:
Similarly, schottky diodes, D1, D2, D3 and D4, minimize overshoots with respect to VDD and schottky
diodes, D702, D703, D704 and D728, minimize undershoots with respect to power ground. For maximum
effectiveness, these diodes must be located close to the output pins and returned to their respective VDD
or PGND pins. Diodes D1, D2, D3 and D4 are only required for applications where VDD>13.5V. Voltage
overshoots can also be caused by output inductor flyback during high current switching events such as
shorted outputs or driving low impedances at high levels. If these capacitors and diodes are not close
enough to the pins, electrical overstress to the part can occur, possibly resulting in permanent damage to
the TA2020-020
So yeah, this is probably what I need. I came here because if you look at the bold part, where it says that overshoot diodes are only necessary when VDD > 13.5v, and this is not the case here so I thought that the overshoot diodes will not help much.

Thank you for your help.

Last edited by LosNir; 12th March 2010 at 03:13 PM.
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Old 13th March 2010, 03:41 PM   #6
r0b is offline r0b  Germany
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Default Other Question

What are you experimenting with that connects the outputs of two amps? Maybe you should investigate there also
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Old 13th March 2010, 04:06 PM   #7
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Nothing, I'm just stupid and instead of pulling out the cables from the amp, I pulled the cables from the speakers and connected the output together.
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Old 13th March 2010, 08:27 PM   #8
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What should be more suitable for the overshoot schottky diodes, 1N4002 or 1N5819?
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Old 16th September 2010, 07:25 AM   #9
amuppet is offline amuppet  United Kingdom
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Hi everyone - when people talk about removing the zener diode, does that mean replacing it with a wire, or literally just cutting it/desoldering it out and leaving nothing (just air) in place between the two terminals it used to link?
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Old 17th September 2010, 06:11 AM   #10
col is offline col  Australia
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Quote:
Originally Posted by amuppet View Post
Hi everyone - when people talk about removing the zener diode, does that mean replacing it with a wire, or literally just cutting it/desoldering it out and leaving nothing (just air) in place between the two terminals it used to link?
Yes, leave it open.

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