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Old 19th August 2012, 01:55 PM   #1221
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I have received 3 new 2020A+ from ebay.
They have the new PCB (red one version 120301) I guess version number on pcb is YearMonthDay of pcb design.(same as post #1203)

I have some small plop sound with this amp : - small pop when relay commutes 2 seconds after powering on.
- bigger pop when switching off.
But it seems reasonable level and should not make any damage to my speaker.

2 of my boards are not working well : sometimes sound level is dropping. I have noticed that pushing on PCB make it happens easily. I feel it is soldering issue on some components. After checking last year posts, it seems no one has posted any schematics of 2020A+ version. Anyone has something that could be shared ? (I just found the naked pcb in Viprz post #935)

thanks
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Old 19th August 2012, 02:47 PM   #1222
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I just a video using new 2020A+

Wharfedale Diamond 10.2 - Bass response #2 - YouTube
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Old 19th August 2012, 06:58 PM   #1223
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Quote:
Originally Posted by panda360 View Post
Looks like subsonic bass, severe turntable rumble can do this.
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Old 19th August 2012, 07:35 PM   #1224
Trileru is offline Trileru  Romania
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Does anyone have a good psu schematic for this amp? I will get mine tomorrow from the postal office and would like to build a psu for it. I also have a PSU from a computer, could I use the 12V from it? I know I could just buy a laptop style psu but it'd be nice if I built it as I could learn some on the way.
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Old 19th August 2012, 07:40 PM   #1225
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Quote:
Originally Posted by panda360 View Post
Yep, my video.

Quote:
Originally Posted by radiosmuck View Post
Looks like subsonic bass, severe turntable rumble can do this.
They're bass tests. I have two videos up there, Wharfedale Diamond 10.2 Bass Response #1 and #2, other song has "Opus Dei Bass Test" song used, other song is "Bassotronics - Bass I love You"
I have two other speaker videos up there as well in which I used TA2020A+ amp, speakers in those videos are old GenExxa GX1000 floorstanders from 80's iirc.

Last edited by lagittaja; 19th August 2012 at 07:54 PM.
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Old 19th August 2012, 08:15 PM   #1226
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I have started the schematics based on my amp and the picture already posted by Viprz. Very helpful.
The input part, including EQ and preamp is ready. I don't have time to make it clean schematics, if someone has some schematics tool, feel free to copy.
I am not 100% sure that I have not mixed some parts... Seems that ref are matching with Viprz pcb, even if some have moved.

In fact, it is quite interesting, input has been totally redesigned on this PCB. It is clear that 2020 and 2020A+ will sound totally different.

Some comments :
1) Both JRC are powered through Q6. I am not sure of the purpose of this, I have nearly the same voltage on Ic supply and main. any idea ? (Kind of soft start)
2) There is 2 amplification stage : one for main volume, and one for EQ. U2 is for main volume, U1 is for EQ.
3) The "EQ bypass" bypass U1 and the EQ part, and shorten audio path.
4) the volume potentiometer have no pin connected to ground : potentiometer is part of the feedback loop of U2. It make a "long" feedback loop

I have not checked the other parts, but I will attach my first part of the puzzle. Hope it will help.

ihbar
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Old 20th August 2012, 01:38 AM   #1227
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Quote:
Originally Posted by lagittaja View Post
Yep, my video.



They're bass tests. I have two videos up there, Wharfedale Diamond 10.2 Bass Response #1 and #2, other song has "Opus Dei Bass Test" song used, other song is "Bassotronics - Bass I love You"
I have two other speaker videos up there as well in which I used TA2020A+ amp, speakers in those videos are old GenExxa GX1000 floorstanders from 80's iirc.
How can it be be bass tests if you cannot hear it. I tried to listen to your youtube offering through 15 inch drivers and there was not a sound when the cone was flapping around.
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Old 20th August 2012, 12:38 PM   #1228
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Quote:
Originally Posted by radiosmuck View Post
How can it be be bass tests if you cannot hear it. I tried to listen to your youtube offering through 15 inch drivers and there was not a sound when the cone was flapping around.


I'm not sure if you're serious...
Maybe you should listen to the ORIGINAL song instead of a RECORDING done with a phone..
Bass Test - Opus Dei - YouTube
Bassotronics - Bass, I Love You - YouTube
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Old 20th August 2012, 12:53 PM   #1229
Trileru is offline Trileru  Romania
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My MUSE M20 EX TA2020 amp just arrived. I opened it and looks nice and clean. I like the quality of the build. It is compact and very solid. Haven't got a chance to test it yet as I need a psu but will do in the next days. I only opened it to check the insides. My only problem is with the soldering, doesn't seem to be really good, some pins are not completely covered in solder. I will have to touch most of them when I'll be making some upgrades to it. Right now I wonder what would the PSU cap be so I can exchange for a larger one. The inductors seem sturdy but I'll replace those as well. What does the 100 on them mean?
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File Type: jpg 1.jpg (522.7 KB, 352 views)
File Type: jpg 2.jpg (484.8 KB, 303 views)
File Type: jpg 3.jpg (432.7 KB, 296 views)
File Type: jpg 4.jpg (627.0 KB, 284 views)
File Type: jpg 5.jpg (534.7 KB, 114 views)
File Type: jpg 6.jpg (251.1 KB, 98 views)
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Old 20th August 2012, 08:26 PM   #1230
Trileru is offline Trileru  Romania
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The ebay description says that the inductors are Toko fixed inductors. the 100 mark means 10uH so I traced to this datasheet:
A7503AY-100M datasheet(1/1 Pages) TOKO | Fixed Inductors for Digital Audio Amplifier

model A7503AY-100M shielded
But not sure on that. Should I change them with toroidal type? The datasheet rates it for 4.32A.
Also which one is the power cap that is recommended to be changed to at least 4700uF/16V ? The small golden one? I'm asking here since the schematic must be real similar to the Lepai amp.

***later edit***
I found a Cisco Router psu that is rated 12V at 5A and connector fits perfect.
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