Lepai T2020A+ Repair/Upgrade

[XtremeRevolution]

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.




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!

[Wokoran]

Re: Lepai T2020A+ Repair/Upgrade

You can buy electrical components from Digikey or Mouser. I modded the Dayton DTA-2 using the modifications on Michael Mardis' website. The circuit wasn't exactly the same because he was modding the Sonic Impact T-amp which is just like the Dayton DTA-1. It involved bypassing the input section of the amp and inserting new filter caps (I used some Dayton Poly Caps) to improve the bass response of the amplifier.

Of course you'd want to start by fixing your amp first and replacing the cap that burst and scrubbing off the goop with a toothbrush and some tech-grade isopropyl alcohol.

Edit:
http://minirig.org.au/2009/05/08/hot...-lepai-ta2020/ found this just a second ago. This guy apparently replaced some of the components with more desirable ones. Didn't read the entire thing and his looks a little different than yours (his doesn't have any surface-mount components but this will give you a general idea of some of the things you can do (i.e. replace the pots with good ones, replace certain caps with better quality ones, etc.).

[tron]

Re: Lepai T2020A+ Repair/Upgrade

Kind of strange the cap when up in smoke like that. It could have been a bad part. This does happen. That looks like a power supply cap so the (-) side of this cap should go to the ground side of the power supply. I would first remove the cap and clean the board up as the other guy mentioned. I would then investigate the orientation of this cap before replacing it. If it was installed backwords then it would fail as it did for sure. Use a meter and run continuity to ground on each pole of the cap pads and see which one is ground and reinstall the cap with the (-) on the ground side.

This is a guess as I don't have a schematic!! Something to try anyway.

tron

[XtremeRevolution]

Re: Lepai T2020A+ Repair/Upgrade

Kind of strange the cap when up in smoke like that. It could have been a bad part. This does happen. That looks like a power supply cap so the (-) side of this cap should go to the ground side of the power supply. I would first remove the cap and clean the board up as the other guy mentioned. I would then investigate the orientation of this cap before replacing it. If it was installed backwords then it would fail as it did for sure. Use a meter and run continuity to ground on each pole of the cap pads and see which one is ground and reinstall the cap with the (-) on the ground side.

This is a guess as I don't have a schematic!! Something to try anyway.

tron

Well, what I can do that's pretty simple is to open up my amp or the replacement that's coming in and see if anything was done incorrectly.

Does it matter how big the power supply cap is? I'd like to get something a tad larger since I've noticed my amp tends to turn off on itself if I crank it a bit loud and the bass beats hit too hard. The lights will start dimming more and more the louder I turn it up till the amp just turns off. I have about 6 330uf caps that I need to find a home for, that I was going to use as a first order high pass on a subwoofer as a subsonic filter. Or do these caps work differently?

[Wokoran]

Re: Lepai T2020A+ Repair/Upgrade

A previous poster had a board that shipped with one of the caps reversed: http://techtalk.parts-express.com/sh...d.php?t=222390. It appears he only had to take the bad one out and flip it around (pics are included, it is not the cap that blew up on your board). You could probably use any cap you want to replace the old one, but if it is a polar cap then of course you need to follow the polarity that should be noted on the circuit board once you remove the old capacitor. Who knows, it could have just been the wrong polarity.

Putting a beefier cap there is probably a good idea, just don't go insane because some boards are not designed to handle extremely large amounts of capacitance.

[Wokoran]

Re: Lepai T2020A+ Repair/Upgrade

Actually, correct me if I'm wrong but if you look at the picture of the one that is working on that previous post and you look at your circuit board, it appears that your capacitor is reversed. The polarity band on your capacitor is pointing towards the heatsink whereas on the working amp the band is pointed away from the heatsink.

[XtremeRevolution]

Re: Lepai T2020A+ Repair/Upgrade

Actually, correct me if I'm wrong but if you look at the picture of the one that is working on that previous post and you look at your circuit board, it appears that your capacitor is reversed. The polarity band on your capacitor is pointing towards the heatsink whereas on the working amp the band is pointed away from the heatsink.

Nice catch! I guess I found my problem. I will try to replace that cap with one of the ones I have and see if it works. Problem is, these original caps have the wires coming out of one end for circuit board soldering. My caps have the wires coming out of both ends. I don't know what they're called as I don't have enough experience with this, but where can I buy replacement caps of the same type?

Any ideas of what other parts I can replace on here to improve performance? I wonder if the caps used here are any good or if I would benefit from using her capacity caps. I know the guy you posted did that but I have no idea where he got his.

Edit: sounds like I need a type of radial capacitor...

[johnnyrichards]

Re: Lepai T2020A+ Repair/Upgrade

Nice catch! I guess I found my problem. I will try to replace that cap with one of the ones I have and see if it works. Problem is, these original caps have the wires coming out of one end for circuit board soldering. My caps have the wires coming out of both ends. I don't know what they're called as I don't have enough experience with this, but where can I buy replacement caps of the same type?

Any ideas of what other parts I can replace on here to improve performance? I wonder if the caps used here are any good or if I would benefit from using her capacity caps. I know the guy you posted did that but I have no idea where he got his.

Edit: sounds like I need a type of radial capacitor...

Pick your poison, and pay close attention to physical size.

[XtremeRevolution]

Re: Lepai T2020A+ Repair/Upgrade

Pick your poison, and pay close attention to physical size.

LOL Wow. I didn't even know PE sold radial caps.

I guess that solves that problem. Time to do some measuring. Maybe getting a large cap will solve my dimming problem and get me more usable power? I can't imagine that tiny cap doing much of anything for heavier bass duty.

Now I just need to find a way to get a bigger and better heatsink on the tripath chip, perhaps even one that would extend to the chassis to dissipate heat into it as well. Some chassis vents might even be enough.

Would there be much of a reason to replace all of the other caps on the board with higher quality ones?

[Wokoran]

Re: Lepai T2020A+ Repair/Upgrade

Only replacing certain caps will make any difference, problem is with all of the surface mount parts sometimes it can be difficult to identify (without a schematic) the specific sections of the circuit you are actually looking at. The man who modded his Lepai apparently replaced the power caps with some nice Panasonic 2200uF caps in parallel: so I guess in his case 4400uF worth the capacitance was perfectly ok. That would probably fix the dimming. Other than changing the power caps, I'd see if I could find a better power supply: from what I've read about a lot of these t-amps that's one of the "go to" mods for increasing performance.

[XtremeRevolution]

Re: Lepai T2020A+ Repair/Upgrade

Only replacing certain caps will make any difference, problem is with all of the surface mount parts sometimes it can be difficult to identify (without a schematic) the specific sections of the circuit you are actually looking at. The man who modded his Lepai apparently replaced the power caps with some nice Panasonic 2200uF caps in parallel: so I guess in his case 4400uF worth the capacitance was perfectly ok. That would probably fix the dimming. Other than changing the power caps, I'd see if I could find a better power supply: from what I've read about a lot of these t-amps that's one of the "go to" mods for increasing performance.

At this point I'm not too concerned with taking the time to replace the other caps if I know I can get better ones like the guy who modded his. They seem to be fairly inexpensive, so that's not too big of a deal.

With regard to the power supply, someone over on diyaudio told me that the 12V 2A power adapter *should* be all that I need. Most people who I've heard that had issues with power supplies had the old 13.5V 2A power supplies and going to the 12V 2A power supply fixed their problems entirely. The newer models have since shipped with the 12V 2A power supplies.

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.

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?

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.

Based on the above, it seems that the only thing I can really do to get more stable power is to get some bigger input reservoir caps in there. If that fixes my dimming problem during hard bass beats, I'll have found my solution and might actually get a full 20W RMS per channel out of this little amp. If not, a 3.5-4.0 amp power adapter would be in order.

[PWR RYD]

Re: Lepai T2020A+ Repair/Upgrade

What did it come with for a power adaptor (volts and amps)?

[XtremeRevolution]

Re: Lepai T2020A+ Repair/Upgrade

what Did It Come With For A Power Adaptor (volts And Amps)?

12v 2a.

[XtremeRevolution]

Re: Lepai T2020A+ Repair/Upgrade

I noticed something interesting. This ebay seller includes a 12V5A power adapter with this amp:

http://cgi.ebay.com/Lepai-Class-T-Tr...-/290534659322

The problem I have is trying to find a power adapter that would have right connector to fit in the back of the amp.

[PWR RYD]

Re: Lepai T2020A+ Repair/Upgrade

You mean like these?

http://www.parts-express.com/wizards...TOKEN=83270308