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-   -   Led blinking on ta2020 and smps after new caps (http://www.diyaudio.com/forums/class-d/223512-led-blinking-ta2020-smps-after-new-caps.html)

Xerxes75 13th November 2012 06:58 PM

Led blinking on ta2020 and smps after new caps
 
After playing with my Arjan helder ta2020 for a time I went for upgrading the powercap from elna 4700uf 35v to 2 times nichicon 4700uf 100v.

The led on the the SMPS and the ta2020 do switch on but now blinks, I have tried to find post about this but can't find them. It is probably simple and I am just over looking something....

For the meanwhile I back to the elna, but I really want to know what I am missing.

NissanSR20Man 13th November 2012 10:08 PM

I would start with cap polarity. It is possible you have a bad cap too. Time for the multimeter. If all else fails... remove one cap and see if the SMPS is going into a current trip/limit during startup. If it works with either one of the new caps this is probably the problem.

Xerxes75 14th November 2012 06:37 AM

I checked the soldering the polarity and I checked the caps separate that works out ok. So I think it must be the current limit. I there a way to make this work or must I stay with the original cap?

NissanSR20Man 14th November 2012 11:34 AM

What is the brand of SMPS? If Connexelectronic brand you could easily speak with Cristi directly. If a diy or other brand, one could use a hybrid soft start of sorts...

Charge the filter caps through a resistor after the SMPS to limit the current and then switch the resistor out of circuit. If you are really crafty you could do this 100% diy on a PCB, either making your own or using a purchased kit and altering it. Most soft starts are designed for use on the AC side, not the DC side. These kits are fully automatic with relays.

If you want down and dirty... Just get a properly rated toggle switch to bypass the resistors. This is probably frowned upon by someone, oh well. Let them complain. This method is brutally simple... Proper rated resistor in line with the DC+, a toggle switch in parallel. Flip the switch to open position to start up, then flip again to close and to bypass the resistors. Simple. If using dual DC rails, then you need 2 resistors and a double pole, single throw switch. These are cheap and readily available at any real hardware/automotive store. Pay attention to voltage ratings and current ratings please.

I suppose you can get down in the weeds of the details by calculating an inline choke/inductor to limit the current rise, but will drop some voltage at higher current levels. I am unclear of your knowledge level, hence the simple to complex answer. I'm a redneck with a degree, smart enough to know better, but still find it is fun to find new uses for duct tape!

Bare 14th November 2012 03:42 PM

Refit the Original Cap. Clearly the inrush current is too much for the supplied bits in that Amp circuit. Or possibly even the Cheap *** SMPS.
The Tripath data sheet lists 2 x 180 uf caps .
But Hey! what would Tripath know.
Bigger is better.. every internet inmate knows that :-)

NissanSR20Man 14th November 2012 04:48 PM

In the world of DIY there is no incorrect answer. There are answers that result in burnt components and death, and then there are answers that result in success. It is the person doing the DIY that determines how to measure the success. In this instance the individual asked a question, probably with little knowledge of electronics judging by the question and expected an answer. After his question sat unanswered due to the brilliant minds of this website not wanting to be bothered, I replied. Since my ghetto fabulous redneck suggestion of a toggle switch instead of a new, custom pcb the criticism begins. If anyone wants to modify anything they are assuming a risk of it not working, blown parts, or even death. The OP is beyond that already, he has made the decision, and is asking support.

For reference...
The original post referenced a helder audio products mk3 ta2020 which uses a single 6800uF capacitor belonging to him, in actual operation. I did look this up to confirm a person is not replacing a tiny cap with essentially a battery of a cap in order to make is sound like a $40k class a amp. Connexelectronics also manufactures a ta2020 with 2 x 10000uF caps installed. I did verify this prior to my stupid comments to ensure I did not disappoint someone trying to achieve unrealistic expectations by using my stupid ideas.

If tripath was correct about everything, why are they no longer in business?

nigelwright7557 14th November 2012 08:21 PM

Class d amps can sometimes be touchy about extra capacitance.
When I upgraded my power supply to 20,000uf per rail I got huge power off thumps and a siren like sound through the speaker on turn off.

Xerxes75 29th November 2012 07:08 AM

I have bin away for while so sorry for the late reply. Thanks for your input. I have changed the original cap back and now it gets strange. The led keeps blinking when I turn it on, but when I disconnect the speakers and reconnect them the blinking stops....

When I turn off and on again it's the same cycle...

And on the moment just before they are disconnecting your can hear the blinking thru the speakers as soft ticks....

nigelwright7557 30th November 2012 12:07 AM

Quote:

Originally Posted by Xerxes75 (Post 3240337)
The led on the the SMPS and the ta2020 do switch on but now blinks, I have tried to find post about this but can't find them. It is probably simple and I am just over looking something....

For the meanwhile I back to the elna, but I really want to know what I am missing.

SMPS don't like highly inductive or capacitive loads.
The SMPS takes care of smoothing so you need very little on your amplifier boards.

Xerxes75 30th November 2012 06:39 AM

ah thanks....


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