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Old 18th March 2013, 12:21 PM   #171
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Originally Posted by Fukinagashi View Post
After a while the resistors got very hot and then I measured about 12V DC at the outpus of the Lepai!

The only differences respect to original schematics is that I did not use any DC blocker as I'm sure that pre-amp has not any residual output DC.
Measure your pre-amp, don't guess! Then multiply what you measure by 20 and that's about what your speakers will see.

Where did you measure the outputs with respect to? + to - or + to ground? This is a bridged amp with a single supply, there's probably +12V on + AND - with respect to ground, which gives 0V between + and -.
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Old 18th March 2013, 01:52 PM   #172
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Originally Posted by Redshift187 View Post
Measure your pre-amp, don't guess! Then multiply what you measure by 20 and that's about what your speakers will see.

Where did you measure the outputs with respect to? + to - or + to ground? This is a bridged amp with a single supply, there's probably +12V on + AND - with respect to ground, which gives 0V between + and -.
Unfortunately I measured 12V on + AND -.
I've ordered another Lepai: in case I want to remove the pot should I get the signal directly from the RCA inputs or between R37 and R34?

Last edited by Fukinagashi; 18th March 2013 at 02:00 PM.
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Old 18th March 2013, 11:03 PM   #173
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Originally Posted by Fukinagashi View Post
Unfortunately I measured 12V on + AND -.
I've ordered another Lepai: in case I want to remove the pot should I get the signal directly from the RCA inputs or between R37 and R34?
doesn't matter.. keep the decoupling caps to be safe I guess.
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Old 19th March 2013, 12:13 AM   #174
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Originally Posted by Fukinagashi View Post
Unfortunately I measured 12V on + AND -.
I've ordered another Lepai: in case I want to remove the pot should I get the signal directly from the RCA inputs or between R37 and R34?
Do not go from between R37 and R34. Either go from the pads on C30/C31, or straight from the input jacks.
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Old 19th March 2013, 11:47 AM   #175
danzz is offline danzz  Spain
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Originally Posted by Fukinagashi View Post
Unfortunately I measured 12V on + AND -.
I've ordered another Lepai: in case I want to remove the pot should I get the signal directly from the RCA inputs or between R37 and R34?
Take a Look at the datasheet, there is a fault pin, check the voltage there, to be sure that the chip its gone... If its gone... You always can order only the TA2020 IC, and change it... It Will be always cheaper than ordering a new lepai... Its what I did with My first lepai that blew cause I desoldered without discharging the input big cap... And now I have that one working with a total tone/volume components removed ... And its has a great sound...
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Old 19th March 2013, 11:39 PM   #176
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Originally Posted by danzz View Post
Take a Look at the datasheet, there is a fault pin, check the voltage there, to be sure that the chip its gone... If its gone... You always can order only the TA2020 IC, and change it... It Will be always cheaper than ordering a new lepai... Its what I did with My first lepai that blew cause I desoldered without discharging the input big cap... And now I have that one working with a total tone/volume components removed ... And its has a great sound...
danzz I see on the data sheet that fault pin is #18 but which voltage should I expect to exclude possible failures?
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Old 20th March 2013, 03:49 AM   #177
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From looking at the datasheet it says 5V for fault, and I would presume 0V for no fault.
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Old 20th March 2013, 10:14 AM   #178
danzz is offline danzz  Spain
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Originally Posted by Redshift187 View Post
From looking at the datasheet it says 5V for fault, and I would presume 0V for no fault.
Also can check pin 6 Which its the overloadb pin, you should have 5V in there as it says in the datasheet...

Overload
The OVERLOADB pin is a 5V logic output. When low, it indicates that the level of the input signal has overloaded the amplifier resulting in increased distortion at the output. The OVERLOADB signal can be used to control a distortion indicator light or LED through a simple buffer circuit.


About the fault pin...

Fault Pin
The FAULT pin is a 5V logic output that indicates various fault conditions within the device. These conditions include: low supply voltage, low charge pump voltage, low 5V regulator voltage, over current at any output, and junction temperature greater than approximately 155C. The FAULT output is capable of directly driving an LED through a series 2KΩ resistor. If the FAULT pin is connected directly to the MUTE input an automatic reset will occur in the event of an over-current condition.
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Old 20th March 2013, 01:30 PM   #179
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TX. I will try tonight. In the meanwhile the new Lepai arrived.
How did u tested the amp after mods? Did you shortened the inputs and the outputs before wiring the amp to the speakers?
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Old 20th March 2013, 09:56 PM   #180
danzz is offline danzz  Spain
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Originally Posted by Fukinagashi View Post
TX. I will try tonight. In the meanwhile the new Lepai arrived.
How did u tested the amp after mods? Did you shortened the inputs and the outputs before wiring the amp to the speakers?
No, I directly conected the iPhone as a source and some little speakers I made with some Tang Band w3 665SC I made for this purpouses...
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