Lepai T2020A+ Repair/Upgrade - diyAudio
Go Back   Home > Forums > Amplifiers > Class D

Class D Switching Power Amplifiers and Power D/A conversion

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 20th April 2011, 05:11 AM   #1
diyAudio Member
 
Join Date: Feb 2011
Location: Northern Illinois
Default Lepai T2020A+ Repair/Upgrade

Alright, so I've been using my Lepai amp for well over 2 months now. No problems, runs great. I decided to order two more. I was about to send them to my mom and brother but I figured I'd test them first. I tested the first one, and within 15 seconds there was smoke blowing out every crevice available.

I called up PartsExpress the next day and they sent me a new one free of charge and told me to keep the other one for spare parts or toss it. I figured I'd play with it a bit, so I took it apart.

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

It appears that what used to be an electrolyte capacitor exploded and left a sticky residue on much of the amp.

So I need some help. I have heard that people have been modding these for a while, but I find very few resources on the actual mods being done. I'd like to replace all of these capacitors with solid state capacitors as a start, and hopefully do something to improve the performance a bit.

Anyone know where I can get the needed parts? Is there a modding thread for these anywhere? I'd like to get some more output and replace parts with better parts to improve sound quality which I have heard has been done with some of these. If there's a thread somewhere that I missed, then that's all I'd really need. I'd also need to know where to get the parts I'll be replacing.

Also, does anyone know where I can get a more powerful power adapter for this? 12V at 2 amps wouldn't give me more than 24W total, yet this thing is supposedly rated for 20W RMS x 2. I imagine a 4 amp power adapter would do?

Thanks in advance!

Last edited by XtremeRevolution; 20th April 2011 at 05:13 AM.
  Reply With Quote
Old 20th April 2011, 05:55 AM   #2
diyAudio Member
 
Saturnus's Avatar
 
Join Date: Jun 2005
Location: Copenhagen, Denmark
Aren't solid state capacitors limited to 2.3-2.5V types? Either way they're designed for very high frequency circuits and would do rather poorly in audio.

Technically you'd not need a bigger PS as you're not listening to test signals. The typical power consumption when turned up to just before audio clipping is less than 400mA with 4 ohms speakers.
  Reply With Quote
Old 20th April 2011, 05:57 AM   #3
diyAudio Member
 
Join Date: Feb 2011
Location: Northern Illinois
Quote:
Originally Posted by Saturnus View Post
Aren't solid state capacitors limited to 2.3-2.5V types? Either way they're designed for very high frequency circuits and would do rather poorly in audio.

Technically you'd not need a bigger PS as you're not listening to test signals. The typical power consumption when turned up to just before audio clipping is less than 400mA with 4 ohms speakers.
I guess solid state wouldn't be appropriate after all, lol. That's why I asked.

If the power supply is fine, that's great to hear. I was just wondering how something can input 24W and output 40W. Any information on replacement parts to make it sound better, or at minimum, a replacement cap to make this unit work again?
  Reply With Quote
Old 20th April 2011, 06:11 AM   #4
diyAudio Member
 
Saturnus's Avatar
 
Join Date: Jun 2005
Location: Copenhagen, Denmark
RMS stands for Root of Means squared, ie. it's the average energy level of a sinus wave.

Music signals in order to have any dynamic information have far lower average level. In tests a test signal simulating this is called a gaussian signal. The typically used test signal, and thereby music signal, these days have an average energy level 8 times lower than a sine wave signal.

So with real life use the average power output is actually under 5W total for both channels. There will naturally be peaks but most of this a soaked up by the power supply's overcapacity and the rest by the resevoir cap in the amp.

I would myself prefer a 3A supply but for 90% of all realistic use a 2A is actually fine.

Last edited by Saturnus; 20th April 2011 at 06:15 AM.
  Reply With Quote
Old 20th April 2011, 02:58 PM   #5
diyAudio Member
 
Join Date: Feb 2011
Location: Northern Illinois
Well I guess that will have to do. The reason why I asked is that when I play some music at higher volumes with hard bass beats, the light on the volume knob will dim, indicating a loss in voltage.

Based on my knowledge of car audio, this will indicate a voltage drop due to insufficient power. That's why I was wondering if my 2A power adapter is enough or if I should look at something more capable.

With regard to the input cap that blew up, does it need to be a special kind of cap, or can I use any general capacitor? I have 6 330uf caps I was going to use for a subwoofer high pass filter and ended up not needing them for my application, and would love to find a new home for them. Can I just wire up one of those in place of the little cap currently there?
  Reply With Quote
Old 20th April 2011, 05:51 PM   #6
diyAudio Member
 
Join Date: Feb 2011
Location: Northern Illinois
Apparently partsexpress sells radial caps, which is what I need to replace on my board.

Any other random advice would still be appreciated though.
  Reply With Quote
Old 20th April 2011, 08:21 PM   #7
diyAudio Member
 
Join Date: Feb 2011
Location: Northern Illinois
I have to admit I was genuinely baffled by the number of people who have "hot rodded" these amps in the big thread in this section. However, not a single person made a writeup on how it should be done, what should be purchased to replace what, and what difference each component makes. I found my replacement for the large input cap that fried, but that's as far as I got, even though I also saw people replacing the 4 inductors parallel to the heatsink and more of the caps all over the boards, among other things I have no knowledge of. If anyone knows of a more concise writeup of what can be done with this amp instead of a dozen or more "hey look what I did with my amp" post assuming everyone knows what they're talking about, I'd very much love to read it.

If not, I'd also very much appreciate it if someone can help me understand what can be improved here so at least I can write something up for other people.
  Reply With Quote
Old 21st April 2011, 06:04 AM   #8
diyAudio Member
 
Join Date: Feb 2011
Location: Northern Illinois
Alright, this has me royally confused.

The power adapter that came with the amp is supposedly rated for 2A at 12V. I went digging through a few boxes to find some comparable power supplies and found nothing that did 2A. Actually, the only one that was a comparable size and weight could only output between .6a and .85a.

I took some pictures.

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

The large power adapter as you can see is rated for 12V 1A, while the Vonage power adapter (which is what comes with the Lepai amps) is rated for 12V 2A. However, the 1A power adapter is twice as heavy, its almost twice as big, yet its rated for half the output?

"does not compute"
  Reply With Quote
Old 21st April 2011, 06:45 AM   #9
diyAudio Member
 
Join Date: Feb 2011
Hi,

The light small plug pack is an electronic power supply (SMPS), while the larger heavier plug pack uses an iron-core transformer.

The differences are similar to those between an SMPS (Switch Mode Power Supply) and a bulky transformer, rectifier, and large capacitors (and possibly a regulator) that you might use inside a larger amplifier case, except that these power supplies can be larger and of higher capacity than the plug packs.
  Reply With Quote
Old 21st April 2011, 03:34 PM   #10
diyAudio Member
 
Join Date: Feb 2011
Location: Northern Illinois
Quote:
Originally Posted by Sounds Great View Post
Hi,

The light small plug pack is an electronic power supply (SMPS), while the larger heavier plug pack uses an iron-core transformer.

The differences are similar to those between an SMPS (Switch Mode Power Supply) and a bulky transformer, rectifier, and large capacitors (and possibly a regulator) that you might use inside a larger amplifier case, except that these power supplies can be larger and of higher capacity than the plug packs.
That makes sense. thanks for the explanation.

Moving on to parts that could be replaced. Since this is a chinese made $20 amp, I am under the assumption that just about every part inside will have been made with every effort to cut costs and thereby are the lowest quality available. If that is not true, I'd love to know. In any case, here are the parts I've been able to find that can be replaced easily.


The parts list is as follows:
Input capacitor
1 x 16v 3300uf

Other/Output electrolytic capacitors
2 x 16v 100uf
1 x 16v 470uf
2 x 16v 220uf
2 x 50v 1uf
2 x 50v 1.7uf

Other/Output film capacitors
1x 63v .1uf - 104j
6x ?v .47uf - 474z

Inductors:
5 x 10uH - 100k

I didn't calculate the value of the tiny worm-like band color things, presumably resistors. Didn't seem like anything significant enough to bother with, but I'd like to know if I should be replacing those as well.

Being essentially a Class D amp, I have heard that the inductor quality is important. Can anyone comment on this? Any suggestions as to what kinds of capacitors I can use to replace the current ones?
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Lepai T-Amp with TA2020 Fin Class D 1921 10th July 2014 05:25 AM
Lepai V3 with TDA8566 Electro-Chip Chip Amps 4 3rd January 2012 05:04 PM
Lepai TA2020 westsounds Class D 5 3rd January 2010 08:03 PM
Are these two Lepai amps actually the same? goodgnus Class D 4 14th October 2009 01:28 AM


New To Site? Need Help?

All times are GMT. The time now is 01:44 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2