Point 2 Point (no PCB) for TDA7293, TDA7294, TDA7295, TDA7296. - Page 9 - diyAudio
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Chip Amps Amplifiers based on integrated circuits

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Old 26th February 2013, 01:04 AM   #81
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All efforts in vain, Now i think it is the problem in the Amp itself,,I have change speakers n cables but no use. Now the discharge imbalance is equal for both the Amps .
The only remaining trick in the amp is changing standby cap from 22uf to 10 u f
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Old 26th February 2013, 03:21 AM   #82
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You have dual secondaries, dual rectifiers.
In the only working way to re-order the batteries in a two cell flashlight, you can likewise re-order those bridge rectifiers. See if the imbalance relocates or changes.

EDIT:
That procedure wouldn't help a stereo amp that has only one channel of imbalance. Are both channels the same or is there one different than the other?
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Last edited by danielwritesbac; 26th February 2013 at 03:29 AM.
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Old 26th February 2013, 04:21 AM   #83
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Quote:
Originally Posted by danielwritesbac View Post
You have dual secondaries, dual rectifiers.
In the only working way to re-order the batteries in a two cell flashlight, you can likewise re-order those bridge rectifiers. See if the imbalance relocates or changes.

EDIT:
That procedure wouldn't help a stereo amp that has only one channel of imbalance. Are both channels the same or is there one different than the other?
I have tried swapping bridges,,but still it goes.It is just the same for both amps.And I have measure when amp is poweredd,,there is min imbalance like .1 v,,,,Does 11mv dc offset cause the probs ?..Anyway it doesnt affect the sound.
The led in ? is the negative terminal.
What if i connect the anode to the gnd and 10k resistor from cathode to the negative terminal.In my,your connection it is the opposite.

Last edited by simply14prem; 26th February 2013 at 04:29 AM.
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Old 26th February 2013, 09:08 AM   #84
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I think I have settled the issue.I have connected the + & - of the two bridges as close as possible,,now still trying different speakers.Its now working.
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Old 26th February 2013, 04:12 PM   #85
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Yay! So, wiring it exactly like the power supply schematic works fine?

I have lost track of how many features are in that supply (it is low parts count design so there's a lot of functions not obvious on first glance) and the many reasons for them. Unlike the majority of dual secondaries supplies, it has only one solid (very solid) central ground. There was a good reason for this but I did not remember it. I think you found out though. Thanks!
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Last edited by danielwritesbac; 26th February 2013 at 04:21 PM.
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Old 27th February 2013, 01:41 AM   #86
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Quote:
Originally Posted by danielwritesbac View Post
Yay! So, wiring it exactly like the power supply schematic works fine?

I have lost track of how many features are in that supply (it is low parts count design so there's a lot of functions not obvious on first glance) and the many reasons for them. Unlike the majority of dual secondaries supplies, it has only one solid (very solid) central ground. There was a good reason for this but I did not remember it. I think you found out though. Thanks!
Very solid power supply.I was connecting the opposite terminals of the bridges like Carlos ,,like a bit lengthy wire.But When I connected exactly like you ,,it was just doing fine.thanks again.
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Old 3rd March 2013, 01:19 AM   #87
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Some day I will try LME49830.Hope sound is cool.I have a bad luck with lm3886,,every time I power those ,they become so hot n no sound..fake ones for sure.
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Old 3rd March 2013, 10:01 AM   #88
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http://img256.imageshack.us/img256/1...7293schma2.jpg

I have use this schematic from Francis Ibre for point to point, just reverse the négative rail diode

Last edited by Cuda; 3rd March 2013 at 10:07 AM.
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Old 4th March 2013, 01:33 AM   #89
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The idea is fantastic, but the reliability is hit or miss. On that schematic, it reduces reliability because we shouldn't voltage drop the V- pin, which is substrate. If that is lower voltage than PWV- the chip's internal diode may be overloaded, corrupt, crack, and set the chip and speaker on fire. Voltage drop the substrate = worse than a short circuit. SO, on that schematic, it is probably necessary to parallel that V- diode with a sturdy resistor, which can give you that desired slight isolation effect without the dangerous voltage drop. Must not voltage drop the substrate. I'm not sure what resistor value to Add parallel to that V- diode for guaranteeing that the predrive section never actually experiences a voltage drop. Perhaps 0.47R.

No problem with the V+ diode.

Other part of that schematic, the 33k, diode, and 10u on the mute circuit are useless if you don't need to switch the mute on and off. It is simpler just to use the 10k by itself, if you don't intend to attach switches.
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Old 4th March 2013, 02:12 AM   #90
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Quote:
Originally Posted by Cuda View Post
http://img256.imageshack.us/img256/1...7293schma2.jpg

I have use this schematic from Francis Ibre for point to point, just reverse the négative rail diode
A gainclone TDA,,, isnt that having a 50x gain.I have a couple of schematic where bootstrap cap is 100uf.I like this.
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