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Thread: Modifying a Lepai LP-2020A+ (Blue PCB Type)

  1. #21
    Join Date: Mar 2009

    Location: Sheffield

    Posts: 442

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    Hi Danilo,

    I was very lucky as the Lepai that I bought for £18.99 a few years back has a genuine TA2020 in it. You can still buy the chip from a European distributor for about £9.00, well until stocks run out!

    Really enjoyed modding the little amp and have spent £12.00 to date on it so not bad. The sound quality has really amazed me and it still works well. Not sure what else to try now as I've run out of ideas but have removed the resistors at R42 and R43 since.

    Hope that it lasts as I really like the smooth detailed sound it produces - the pre-amp bypass mod giving the biggest effect and I found the others quite small by comparison.

    Regards

    Chris

  2. #22
    Join Date: Mar 2009

    Location: Sheffield

    Posts: 442

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    Hi Danilo,

    Struggling to find any 10UH toroidal inductors to fit in the Lepai. I was very kindly sent some by Alan but I need to go for a bigger case to fit them in (perhaps the next bit of my project). If you have that will fit that are surplus I would do a deal for them!!

    Regards

    Chris

  3. #23
    Join Date: Mar 2009

    Location: Sheffield

    Posts: 442

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    Just thought that I should post a summary of where I have got to in case anyone else gives the conversion ago.

    1. Bypass Mod. Realised that the numbering on the Lepai boards can be all over the place and that C20 & C21 can be switched on some boards. I have now soldered onto the back of the inputs through a 2.2uf film cap to the C20 and C21 positive sides. On my board the upper red input goes to C20 and the lower black to C21. The sound pulls to one side if you get this the wrong way round. This mod gives the biggest improvement in my opinion. You remove the surface mounted capacitors at C30 and C31 as well (I also removed the resistors R34 to R37).

    2. Input Cap. I removed the supplied cap and replaced it with a 10,000uf electrolytic cap. I also added a small film cap as a bypass. This gives a bit more weight to the sound and worth doing.

    3. Output Caps. I swapped out the six output caps with .47uf Vishay film caps. I used MKT 1822 but wish I had gone for ones with 5mm leg spacing as the 1822 are just too wide. Worth doing but does depend on how good the stock caps are in the first place.

    4.Redundant Component Strip Out. Removed the opamps and all caps and resistors close in Removed vol pot, tone pots and tone switch. Removed all caps and resistors around them. Removed resistors R42 and R43. I think that this just reduces the power drain to the unused parts. I did notice that this mod corrected the DC offset imbalance that I originally had on the outputs.

    5. Capacitor Swap. Replaced the remaining electrostatic caps as follows. C4 & C10 - Nichicon FG 1uf 50v. C13 & C15 - Panasonic FC 220uf 25v. The big one next to C4 - Panasonic FC 470uf 35v. I used what I already had and replaced with like for like capacitance.

    Next up will be the inductors as I managed to locate some 10uh toroidal ones for a few quid and I may also replace the surface mounted differential output caps at C34 and C37 with 0.01uf film caps.

    I have attached a few photos of how it looks - luckily the lid still goes on!.

    I have a datasheet for the TA2020 as well if anyone would like a copy.

    Regards

    Chris
    Attached Images Attached Images

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