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Old 9th November 2011, 09:50 PM   #931
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The volume potentiometer is a likely suspect. It might just be a bad spot in the pot tracking; measure a few times at different pot settings. Then...
You could jumper both channels across the volume control and see if things equal out. If so, then pot replacement or leaving it jumpered is one fix. Or (and this is a last resort "fix") you could keep the pot installed and tweak the op amp gain for one channel. I would wait until I finished the other mods to do this, though, after another balance check.
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Old 10th November 2011, 11:00 AM   #932
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I measured the volume pot resistance and the values were off. I'll probably end up buying an ALPS pot off ebay.
For now I'll try to not notice the 1 or 2 missing db's. I'll probably make a bigger case for it because the stock case just doesn't do the chip inside justice I guess I could also add a resistor in series for the other channel if I use wires from pcb to pot.

Today I will switch the rca input caps to the 2,2uf MKT cap.
What I'm really trying to get my head around is whether to get ne5532's or opa2134. I have understood that the op2134 is a bit more "high end" and newer. Whatever I choose I will probably be very happy
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Old 10th November 2011, 04:41 PM   #933
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Oh noes
I had just added the rca input caps. Sounded better than before and I was listening to some music while scanning ebay for opamps. I decided to try out how loud it could go with the mods.
It did really well and my ears were starting to hurt so I turned it down a bit and then all of a sudden no sound but I did hear the relay switch off.
Now it just lights up with no response at all from the speaker outputs, no pops from the relay either. Still getting 12v up to the relay so far.
Tracing this double layer SMD board isn't fun at all so I haven't tested the relay on its own yet. No ticking or anything when I turn it on (this was a problem on the old version?)
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Old 10th November 2011, 05:54 PM   #934
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Triple posting because I can't see an edit button anywhere.
If I connect what is supposed to be grounded on the relay to ground I get the famous 1hz ticking out of the speakers. Neither fault nor sleep is at 5v, both 0v. Haven't measured while the ticking is happening but I guess that they will then be high.
I have the newest model (blue pcb) so if anyone knows how to disconnect the fault and sleep pins on my model it would help greatly
Don't know if it would work even then but I'm really sad that my great sounding lepai died so young
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Old 14th November 2011, 11:33 PM   #935
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Hello
I've been following all the threads on this forum about tripath based amps and its been a hell of a trip on this very nice forum.
I love music and DIY but happens that i'm not so good with electronics .
So after alot of reading and searching I purchased some tripath boards and finished amps.

I received four TA2020A+ today and while I did purchased the old version with through hole components there is nothing I can do about that.

Three of them worked out of the box and one was dead.I tried to look out for shorts, bad soldering and I even replaced caps but nothing changed.

Two units had awful bass and some hiss while the last one had a much better overall sound quality. I did opened that unit and the one with better sound had black capped inductors while the other two, blue. I don't know if the better sound quality is related to the different inductors but who knows.

Click the image to open in full size.


I know that many of us, lepai ta2020a+ owners want to bypass tone and or opamps and while I don't have the skills to trace the pcb and create a datasheet / find a solution I can always use the dead unit and get it almost naked and that's what I did.

Click the image to open in full size.
Click the image to open in full size.

I hope it helps and if anyone happens to need a photo or details about a specific section of the pcb just ask, please. Bellow I attached some high res photos.

Thank you all.
Attached Images
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File Type: jpg disco 579-9.jpg (835.2 KB, 854 views)
File Type: jpg disco 583-3.jpg (933.2 KB, 69 views)

Last edited by Virpz; 14th November 2011 at 11:35 PM.
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Old 15th November 2011, 05:20 PM   #936
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So if took it right from what was wrote here and what the old version schematics shows. To bypass tone controls and op amps on the pcb 101110 (ta2020a+ ) one just needs to remove c30, c31, c20 and c21. and then connect c30 negative pad to c20 positive using coupling caps and do the same with c31 and c21 ? Do I need to cut traces or remove any other components ?

Thank You

Last edited by Virpz; 15th November 2011 at 05:22 PM.
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Old 15th November 2011, 05:33 PM   #937
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An engineer friend of mine looked at the schematic on this .PDF & pointed out the corresponding components on my PCB. He said it makes sense for the Amp manufacturers to just copy the Tripath diagram.
So are the schematics of the first & later A+ models the same? Is the only difference the components going surface mount?
http://www.e-ele.net/DataSheet/TA2020.pdf
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Old 15th November 2011, 07:48 PM   #938
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That's it.

I put my "dead" unit components on board again and gave it a try first connecting an vu meter to the outputs since I don't own a multimeter and the neddles responded as they should to the volume set and power. I did that to avoid blowing up my speakers in case everything was wrong


To bypass op amps and tone controls on TA2020a+ pcb 101110 you must remove c30, c31, c20 and c21.
Then just connect c31 positive to c21 positive and do the same with c30 and c20. Yes, the caps orientation for c20 and c21 are wrong printed on the pcb.

Click the image to open in full size.

As you can see I used the same bipolar coupling caps that wer originally placed at c20 and c21. I have mundorfs, metal film, nichicons and new inductors on their way to my home already.


Shame on me for asking you guys how to bypass it. It needed only a look at the schemathic of the old lepai, the ta2020 datasheet for pinouts and ta2020a+ pcb. I feel ashamed for asking on how to do it.


Oh i'm pretty happy with the result. No clipping, no hiss I can increase the volume much further with the plesure of having a much better experience. I almost can't believe it is the same amp. I don't need op amps to play louder with the expense of heinous sound quality .

Forgive me if my english su*ks

Last edited by Virpz; 15th November 2011 at 08:13 PM. Reason: Holy sh*t that sound quality rocks
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Old 15th November 2011, 08:41 PM   #939
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What's the fascination with these? The price? They sure are cheap and they have improved the build quality over the years, but they still aren't great.

The 41Hz AMP6 is so much better that to me it would justify the small extra cost.
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Old 15th November 2011, 11:07 PM   #940
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Quote:
Originally Posted by Pano View Post
What's the fascination with these? The price? They sure are cheap and they have improved the build quality over the years, but they still aren't great.

The 41Hz AMP6 is so much better that to me it would justify the small extra cost.
I guess it's also the learning experience that attracts. That was a factor for me when I was starting out. It's somewhat unfortunate that these amps are so very low-quality that they present a bad picture of Tripath amps.

I'll resoundingly second the Amp6. Those are re-li-a-ble, and sound unbelievably good. Out-bass, out-punch any bigger amp you'll ever have heard.
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