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Circuit error in Lite DAC-AH: Easy fix - Page 3

post #31 of 192
10/8/06 at 12:29am
Quote:
Originally Posted by Superpredator
What exactly does this statement mean? Are you talking about other Chinese-made DACs?
the circuit for the DAC-AH was developed for another more expensive DAC. When the Chinese copied it they lowered the voltage to the TDA1543's to avoid overheating rather than adding heatsinks. When they lowered the voltage they made a mistake in that they forgot to change the resistance for R35/R36. So this DAC from Lite clips.
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post #32 of 192
10/8/06 at 6:29am
That's interesting. My DAC-AH does have the correct voltage but then again mine is from 2004 before anyone had discovered it. I have added my own heatsinks. Maybe the latest version has this unfortunate "fix" / error.
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post #33 of 192
10/9/06 at 2:17pm
here's another taker for a 'step by step' dac ah fix- love the sound but that clipping...thanks
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post #34 of 192
10/11/06 at 7:03pm

5% tolerance too much?

I want to fix my DAC-AH... the resistors I bought from RadioShack are 5% tolerance... is that ok or is that too high a tolerance?
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post #35 of 192
10/11/06 at 7:21pm
Thread Starter 
5% is OK. You won't be able to hear 5% (0.2db) difference in volume between left and right channels if there is a mismatch.
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post #36 of 192
10/11/06 at 7:55pm
What's the best way to remove the board so you can have access to the output resistors and capacitors. I don't want to cut wires if possible. How do the digital inputs come loose from the side.
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post #37 of 192
10/11/06 at 11:32pm
kim, could you take a picture of the inside of your dac and point out where the resistors go? I've never soldered before so i'd like as much knowledge as possible before I go at it. Any (more) help would be greatly appreciated. Even if you don't want to, thanks a lot for IDing the problem and already explaining how to fix it
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post #38 of 192
10/12/06 at 2:42pm
Are the maufacturers aware of the problem? I ws going to either get a 203.2 or maybe step up to a DAC-AH when the time came but this little problem has got me worried - I dont have a soldering iron and i wouldn't be up for messing inside anyways. I also need it to stay stock to keep the price down.
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post #39 of 192
10/12/06 at 6:24pm
Quote:
Originally Posted by bpm2000
Are the maufacturers aware of the problem? I ws going to either get a 203.2 or maybe step up to a DAC-AH when the time came but this little problem has got me worried - I dont have a soldering iron and i wouldn't be up for messing inside anyways. I also need it to stay stock to keep the price down.

If you don't want to solder avoid any DAC made in China.
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post #40 of 192
10/12/06 at 6:52pm
Quote:
Originally Posted by regal
If you don't want to solder avoid any DAC made in China.
Whoa that's some BS. I've experienced many chinese DACs and the DAC-AH is the first one i've wanted to touch with a soldering iron; and this isn't because it's flawed (it's GREAT for the price, unmodded), but because it has so damn much modding potential.

If someone was to buy a DAC-AH and not touch it with a soldering iron, they'd be getting a great deal
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post #41 of 192
10/12/06 at 7:33pm
China DAC's are a good value for the money but almost all of them have mistakes/compromises like this. You must be prepared to fix them unless for example with this DAC-AH you like to listen to clipping.
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post #42 of 192
10/12/06 at 9:15pm
Quote:
Originally Posted by regal
China DAC's are a good value for the money but almost all of them have mistakes/compromises like this. You must be prepared to fix them unless for example with this DAC-AH you like to listen to clipping.
All gear from everywhere has mistakes or flaws that can be fixed. Just before I read a post here on headfi stating that the very expensive Benchmark DAC1 uses 50 ohm BNC plugs instead of the correct 75 ohm.

Dont forget that the DACAH gained fame before people started fixing the circuit error.
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post #43 of 192
10/13/06 at 6:21pm
Thread Starter 
Quote:
Originally Posted by eladioc
kim, could you take a picture of the inside of your dac and point out where the resistors go? I've never soldered before so i'd like as much knowledge as possible before I go at it. Any (more) help would be greatly appreciated. Even if you don't want to, thanks a lot for IDing the problem and already explaining how to fix it
Sorry, I can't post a photo because I've removed the resistors in preparation for more mods. The resistors (R35,R36) are located next to the 3rd TDA1543 chip from the edge of the printed circuit board next to the power transformer. Just solder 1/4 watt 5% 330 ohm resistors (I prefer 330 ohm vs. 470 ohm for more margin to clipping) across R35 and R36. Then adjust the trimpot so that pins 5 and 7 of the TDA1543s are at about 3.3V DC (after allowing about 10 minutes for warmup). That's it. The space around R35 and R36 is a little tight so a soldering iron with a thin tip might be required.

Keep in mind this fix is only necessary if your DAC-AH uses 6V for the TDA1543 supply. This can be measured at pin 8 of the TDA1543s. Good luck.
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post #44 of 192
10/17/06 at 5:12pm
Just wanted to chime in and update you guys on what ive done so far to my dac-ah.......

NOTHING!!

Ive been sick as a dog and am just barely recovering from a nasty cold. After a week of feeling like **** I finally gave in and made a Drs appointment. He prescribed some antibiotics and i feel a little better now. All of my parts are in and will start working on it later this week.
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post #45 of 192
10/19/06 at 2:11am
ok so i'm staring at the PCB of my DAC-AH. I see the resistors over R35 and R36. So what I should do is solder 330 ohm resistors to the existing resistors on R35 and R36? What is a good way to go about this? Any help with technique? So my final product will have two resistors (270 and 330) pretty much stacked on top of each other... yes? I'm a total newbie at this... so uh... thanks guys.
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