Lepai T-Amp with TA2020 - Page 105 - diyAudio
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Old 5th January 2012, 07:01 AM   #1041
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Just checked all the connections.. These are the results..

pin no 25 - +9v

pin no 2 - 0v

I didn't manage to find any short circuit..however I noticed 1 blue led is not working ..

What should i do now? If possible can someone please post the list of minimum equipment's I need to run this lepai as a power amp..(without preamp & this will make the circuit more simple & easy to diagnose)....Thanks
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Old 5th January 2012, 12:36 PM   #1042
Franfj is offline Franfj  Spain
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With 9v on pin 25 probably the amp is not getting enough volts to start, use a better power supply, 13.5v is the recommended value on datasheet.
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Old 5th January 2012, 04:09 PM   #1043
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I'm suspecting something to do with the resistors & caps..

I already checked the power supply...It's more than enough to feed the amp..

What I've noticed is that some of the resistors & caps are not showing their correct value..(using multimeter) I'm not sure whether I can replace them since they are so small & not easy to find here..There was a short circuit earlier & probably this cause all these problems.. If you can please tell me the parts need to run just the ta2020 chip..(thisway i can identify which parts are necessary which are not). Thank you very much..
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Old 5th January 2012, 04:17 PM   #1044
Franfj is offline Franfj  Spain
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You can follow the diagram that I've posted before http://www.e-ele.net/DataSheet/TA2020.pdf on the page 5 appears the minimum components needed, DH are not needed if <13.5v

BTW the Lepai setup only differs on the op-amp section, and the protection circuit.

If you only have 9v at pin 25 something is wrong, because on mine at least, there is a direct connection from power supply line (after the big cap) to switch and then to pin 25.
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Old 5th January 2012, 04:58 PM   #1045
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One more thing ... I cannot hear the "click " sound from relay.. Does that mean something wrong...? Thanks
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Old 5th January 2012, 05:25 PM   #1046
Franfj is offline Franfj  Spain
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If can't hear the relay, something is wrong, the relay clicks even without the TA2020 chip (I've checked now on my board without chip). As said before, something is wrong with power, check the power supply or the part of the board.
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Old 5th January 2012, 05:49 PM   #1047
QT0815 is offline QT0815  Germany
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Quote:
Originally Posted by Franfj View Post
Yes, that's what I'm talking about… but look at this post Lepai T-Amp with TA2020 it seems that not all the toroids are equal…

Has anyone tried with both types of toroids?
Hi i like to send you to my post here, i replaced the old toroids with SMD ones. Lepai T-Amp with TA2020

I used this amp for a little sub, and this thing is working wonderful.
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Old 6th January 2012, 03:01 AM   #1048
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Those are very interesting toroids! I didn't know about them. I think Ill try the ones that helder electronics sells first though. Although... these may be much easier to mount on the under side of the board, as opposed to trying to squeeze them in on the upper side of the board.

Thanks for posting these, where did you get them?
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Old 6th January 2012, 08:34 AM   #1049
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Just checked all the connections & i noticed something was wrong with the relay.. (Not 100% sure)

All the power input pins are receiving correct voltage (pin 22 ,25 ,27)

So is it possible to remove or bypass this relay ? (if I'm not wrong its not a must to run this amp)

By the way how to check those tiny caps using the multimeter ?

Thanks..
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Old 6th January 2012, 12:09 PM   #1050
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Location: Coimbra
Hello all. I', really interested in this small amp. But all the 105 pages of info, discussion and mods are a bit to much.
I created a wiki entry for this amp: http://www.diyaudio.com/wiki/Amplifier:Lepai_T_Amp (it is waiting for a moderator to approve it).
If it is approved it would be a great place to put all the filtered information.

What do you guys think?
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