Cigar box
Sorry your amp showed up bad. If you plan to diagnose it yourself, you might want to look at that output relay first. It keeps the speakers cut off for a few seconds at power on. You could try bypassing it.
Finished this yesterday. I took Tyler’s advice and just used metal film PE caps. All were pulled from a large pcb I had in my parts bin. Large power cap is from same. If a smaller cap was used, this would have easily fit back in the case but I really like the looks of it in the cigar box. I didn't get fancy with gold connectors or toroid inductors. I plan to gift this to a family member along with a set of 2-way Dayton speakers.
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Sorry your amp showed up bad. If you plan to diagnose it yourself, you might want to look at that output relay first. It keeps the speakers cut off for a few seconds at power on. You could try bypassing it.
Finished this yesterday. I took Tyler’s advice and just used metal film PE caps. All were pulled from a large pcb I had in my parts bin. Large power cap is from same. If a smaller cap was used, this would have easily fit back in the case but I really like the looks of it in the cigar box. I didn't get fancy with gold connectors or toroid inductors. I plan to gift this to a family member along with a set of 2-way Dayton speakers.
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OK....PE have redeemed themselves. I called for the RA number and when "Stacy" realized it was just a small $20.00 amp, he said not to bother returning it and would ship out another today. I guess it's setup within their system that if it's an "electronic" item (as opposed to "electrical"), a RA number is required.
The up side is that I can play a good bit more with this first one a try to diagnose what is wrong with it. I'm still what I consider an "electronics noob" so this will help me learn a bit.
The up side is that I can play a good bit more with this first one a try to diagnose what is wrong with it. I'm still what I consider an "electronics noob" so this will help me learn a bit.
schematics
Download the TA2020-20 datasheet from the web. Combine the test circuit from the datasheet and Tyler's schematic from his op and you have the Lepai's layout.
Several people have commented that they would power up the unit and have no sound but if they let it sit for a period of time, 10~15mins or so, the sound would finally come through. (not just this version but older ones too) They would ether bypass or replace the relay.
Take the 4 screws off the front and slide the board out. Connect the power cable and switch it on. Do you hear a click from the relay? You should hear one within a secord or so after engaging the power switch. Very audible, you don't have to put your ear to it.
Download the TA2020-20 datasheet from the web. Combine the test circuit from the datasheet and Tyler's schematic from his op and you have the Lepai's layout.
Several people have commented that they would power up the unit and have no sound but if they let it sit for a period of time, 10~15mins or so, the sound would finally come through. (not just this version but older ones too) They would ether bypass or replace the relay.
Take the 4 screws off the front and slide the board out. Connect the power cable and switch it on. Do you hear a click from the relay? You should hear one within a secord or so after engaging the power switch. Very audible, you don't have to put your ear to it.
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I have had the datasheet for awhile. The relays on mine are just that, two separate ones on their own PCB soldered to the main PCB. I have not heard any clicking from them at all. I checked VCC at pins 22, 25, 27, 29 and that was all good. I believe the chip is bad because I didn't get any voltage coming out from pins 21, 23, 24, 26. Looks like I will be getting a new TA2020-020 chip from MCM unless anyone has anything else to check first. I need to order a compression driver from them anyway for a TalkBox I am building.
Got the replacement Lepai in today. Bone stock, right out of the box, I have to say, it lives up to the hype. That is, not bad at all for a $20.00 amp.
I am going to leave this one stock for the time being
and mod/repair the first one probably beyond recognition (almost).
And I did answer my last question myself, after doing a bit more tracing to be sure. The relay does break the connection between the speaker neg. and the amp when the power is off. Regardless, I still do get a "thump", both turning it off and on.
I am going to leave this one stock for the time being
and mod/repair the first one probably beyond recognition (almost).And I did answer my last question myself, after doing a bit more tracing to be sure. The relay does break the connection between the speaker neg. and the amp when the power is off. Regardless, I still do get a "thump", both turning it off and on.
Hi! im new here, saw this thread googling and think maybe any of you can help me, i've got this lepai and it's semi-broken now. When i turn it on, the right speaker do a weird thing and does not sound. It is not a problem of the speaker cos i changed it with the left one and it works. Here is a video of the problem, hoping if anyone know what happen and if i "mod" (change the capacitors) it will work again? Finally, i oppened it and everithing seems in good conditions.
(sorry for the yells, was football day)
Problema altavoces y ampli - YouTube
Thank you very much!
(sorry for the yells, was football day)
Problema altavoces y ampli - YouTube
Thank you very much!
I was contemplating how the Lepai executes the use of the TA2020 chip versus how Tripath shows how in the schematic in their datasheet and was wondering what is the purpose of the transistors in the Lepai? From what I can trace and what little I know, it seems that they are part of the power side of the circuit but I haven't a clue as to how they are used.
Anyone know?
Anyone know?
Why do you say that?
My guess is no one knows the purpose of the transistors. I sure don't. My guess is they are part of the tone circuitry, or maybe function as power supply switching to other parts of the amp.
Someone with a dead Lepai ought to use it to trace out a circuit on paper. I'm not willing to do without listening to mine or I would do it.
BTW, that tilde on the Creative Labs ps strongly suggests it is AC out.
My guess is no one knows the purpose of the transistors. I sure don't. My guess is they are part of the tone circuitry, or maybe function as power supply switching to other parts of the amp.
Someone with a dead Lepai ought to use it to trace out a circuit on paper. I'm not willing to do without listening to mine or I would do it.
BTW, that tilde on the Creative Labs ps strongly suggests it is AC out.
I say it primarily because it's only you and myself posting.
I did do some more tracing and they are tied into the "fault" and "mute" pins on the IC. Best guess is that they are for IC protection or to lessen the turn-on thump.
I am posting a old schematic from the first version of this amp. It was gave me some insight into what the transistors do.
Yea...I was guessing it was AC out and the rest of the power circuitry is inside the sub. If it is AC out, once rectified to DC, the voltage will increase to something that is to high and would need to be reduced. Diodes?
I did do some more tracing and they are tied into the "fault" and "mute" pins on the IC. Best guess is that they are for IC protection or to lessen the turn-on thump.
I am posting a old schematic from the first version of this amp. It was gave me some insight into what the transistors do.
Yea...I was guessing it was AC out and the rest of the power circuitry is inside the sub. If it is AC out, once rectified to DC, the voltage will increase to something that is to high and would need to be reduced. Diodes?
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Having already gotten a 4700uf power cap, gold binding posts and 2.2uf Audyn input caps from PE, I finally just ordered Wurth 10uh 4.7amp inductors, Wima .47uf polyester film caps for the output side, and Switchcraft gold RCA jacks, from Mouser.
I have also bead blasted the top of the case to remove the lettering and have rubbed it back out with 400 wet/dry sandpaper. It gives it a nice brushed look. I am also making some new end plates to accommodate the binding posts, new RCA jacks, and no tone controls. These will have a finish like the top of the case. I am getting rid of the lighted ring around the volume control and instead, using a single LED coming through the front to show it is ON. I am also going to machine a new aluminum volume knob and epoxy one of the old tone knobs inside for the splined insert.
I will post some pics soon.
I have also bead blasted the top of the case to remove the lettering and have rubbed it back out with 400 wet/dry sandpaper. It gives it a nice brushed look. I am also making some new end plates to accommodate the binding posts, new RCA jacks, and no tone controls. These will have a finish like the top of the case. I am getting rid of the lighted ring around the volume control and instead, using a single LED coming through the front to show it is ON. I am also going to machine a new aluminum volume knob and epoxy one of the old tone knobs inside for the splined insert.
I will post some pics soon.
Sounds like where I am with my little project. It's a lot of fun.
I made new end plates, replaced the input caps with Epcos PP caps. Added 2x 5600uF caps for power, I will be winding new inductors soon, replaced spring terminals with banana jacks, added gold RCAs, removed the tone controls... Etc. I'll post some pics of Frankenpai soon.
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