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Lepai Tripath LP-2020A+ mini Amp dissected

So - where is 'Bukang'?


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Not a place name in China, I believe.......

He was a Muslim Warlord in the 30's... but I doubt he is making chip amps now.
 
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chinacave said:
So - where is 'Bukang'?


attachment.php


Not a place name in China, I believe.......

He was a Muslim Warlord in the 30's... but I doubt he is making chip amps now.
Click to expand...

well, who knows? Second career/supplementing his retirement income. Yeah, he's getting up there, you know?
 
Bypass the tone controls (not with the button) and the opamp(s), replace the input coupling caps with something decent. Sounds much better. I have the 2020B board (in a 2020A+ chassis) which is almost all through-hole, for easy tweaking.

Next I will probably do the output inductors and the big supply cap.

Huge tweaking thread for all three versions over at DIYaudio http://www.diyaudio.com/forums/class-d/90500-lepai-t-amp-ta2020.html plus a wiki article... http://www.diyaudio.com/wiki/Amplifier:Lepai_T_Amp
 
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My Lepai arrived from Ebay yesterday with a 3300uf 16v cap instead of the typical 2200uf in a schematic I saw. (Seller said it must be factory, he didn't open it.) Nice stubby cap! Still want to upgrade to 4700uf if I find one 33mm high.

No luck at local GW so far on a 12V 5A supply. I'll keep looking. Cranks out fairly good sound already...Tested with Blue Man Group percussion!
 
Lepai with RCA outputs

To be able to quickly switch speakers, my amp was converted to RCA output jacks from the factory 'push in' wire terminals.

Note, the jacks are mounted on a fiberglass (not metal) panel!
 

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I don't get it.. You buy a product at low cost then modify it.. IMO the cost in hours and $ which I est. approaching double the cost if not more. For less than a yard you can get the whole package without the issues.
 
Never cared for those wire clamp type output connectors. If the wires aren't tinned, the strands can break off inside the clamp. The mod used good quality RCA jacks conncted to the Lepai board with heavy guage wire.

Main purpose was being able to easily change speakers. I must confess, after working in electronics manufacturing I'm always looking at ways to improve hardware.
 
I forgot to mention that I found two of the larger electrolytics to be leaking from the bottom of the caps.

I likey calrec's speaker post replacement. I will add that to the list of upgrades the next time that I get under my Lepai's hood.

I get around the stranded wire problem when hooking up to the speaker clips on these cheap T amps, just tin the ends of the speaker wires.
 
PS...Just installed a compact Panasonic 5600uf 16v (105c) electrolytic cap in the DC input circuit.
Mouser 667-EEU-FR1C562. $1.28. 12v 5A power supply due Thursday!
 
I have a 6800uF 16v on the way, and have also ordered 4x 10uH 6A toroids to replace the junk output inductors. While I am installing those, I am going to bypass the volume control and stick the board into a home-made, wooden chassis connected to a small DIY tube pre-amp and tweak the lepai gain accordingly by changing Rin and Rfeed resistors. Will also upgrade the speaker terminals to proper binding posts at that point and switch to warm white LEDs (which will be installed somewhere near the pre-amp tube). Will also replace the plastic power switch with an old-school metal toggle.
 
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Adden-dum! (Speaker wire spring terminals :(

calrec said:
To be able to quickly switch speakers, my amp was converted to RCA output jacks from the factory 'push in' wire terminals.

Note, the jacks are mounted on a fiberglass (not metal) panel!
Click to expand...

Checked someone's multi channel amplifier that supposedly had dropout issues.
Solid as a rock on the bench!
Problem was one of his $ speakers had a plugged spring terminal that wasn't contacting the wire!

NOT the amp.
 
Lepai power switch issues?
My unit came from Ebay, in nice shape! Seller said it had not been opened. If so, factory must have swapped the older 2200uf cap for a 3300uf? Looked 'reworked'.
The power switch wiring looked crude so I tried to clean it up. Found short pieces of stranded wire in the globs of solder on the (faston type) terminals.
Main shock was the cheap power switch that started to melt when I resoldered the connection! (Will replace it with a new one ASAP)
 
calrec said:
Lepai power switch issues?
My unit came from Ebay, in nice shape! Seller said it had not been opened. If so, factory must have swapped the older 2200uf cap for a 3300uf? Looked 'reworked'.
The power switch wiring looked crude so I tried to clean it up. Found short pieces of stranded wire in the globs of solder on the (faston type) terminals.
Main shock was the cheap power switch that started to melt when I resoldered the connection! (Will replace it with a new one ASAP)
Click to expand...

Mine came with a 3300uF cap as well. Looks like some old POS cap that was recovered from an e-cycling farm. It isn't new, that's for sure.

I'll be replacing the power switch, too. No problem with it so far except it is fugly.

On another note, the TA2020 spec sheet specifies that the (2)output and (1)zobel caps (per channel) should be:

For 4 ohm speaker loads - Co = .47 uF and Cz = .22 uF

For 8 ohm speaker loads - Co = .22 uF and Cz = .22 uF

The Lepai that I have (2020B board) has .47 uF in all 3 (6) positions, and they are crap caps.

I have ordered 10x WIMA .22 uF 50v, as my speakers are 8 ohms.
 
'Replaced the capacitor in mine with a 4700mf/16V unit. It fit with 1/16" to spare (I would have put it sideways if not).
LEDs are covered with white shrink tube (still blue, but not nuclear-bright).

No more turn-off "pop".
I'll do volume tests after I dig out a beefier power supply from my spare parts bins.

(Unit is used for background music; I won't be doing "critical listening", just dB-without-sounding-crappy capabilities.)

Total investment: $22.67
 
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