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Old 29th May 2009, 11:26 PM   #311
aszu is offline aszu  United Kingdom
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Thanks for info col.

They look almost exactly like these

However, they are a bit on a pricey side

Do you think there is much difference between these and metallised polyester film caps I mentioned before?
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Old 30th May 2009, 12:16 AM   #312
col is offline col  Australia
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If you have both the option and the budget the choice scale goes like this:

1st: Polypropylene (often very big and expensive)

2nd: Polyester MKT (much smaller but hard to find in 2.2uF and can be just as expensive as poly, don't sound as good).

3rd: Electorlytic (the cheapest option but can still sound OK)

I wouldn't use Mylar caps as signal input.


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Old 31st May 2009, 02:56 AM   #313
cheric is offline cheric  United States
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I just want to show off my modded Lepai. It does sound so good, much better than in stock form.

I used Panasonic FC 4700uf near the chip and Panasonic NHG 6800uf for p/s.
The signal input caps are MKT 1822 by Ero. BTW, are these better than the Ero MKC 1862?
A friend gave me a couple of each and I am not sure which are the better ones. They barely fit in the box.
I also used OPA2134 for Opamp. I am ordering the NE5532 to try out, may not be as good.
Those little gold caps are Nichicon 2.2uf "Fine Gold".
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Old 31st May 2009, 03:41 AM   #314
cheric is offline cheric  United States
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My error.
Near the chip, I used Panasonic FM 1200uf, not the Panasonic FC 4700uf as previously described.
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Old 31st May 2009, 07:08 PM   #315
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Hey guys, just got back, the Lepai works (or worked) great in the car. I say worked as it is no longer working...

I was listening to some quiet music from an MP3 player, so the volume was up high, maybe on full...

A loud song then came on after, I had around 2 seconds of very loud music and then the amp cut out...

Now all I get when unmuting the amp is a ticking noise. The ticking noise goes when it's muted.

What would be the best way of troubleshooting this? Check for DC offset on the outs?

So far I've check the op-amp is getting power, I'll try and find some small caps so I can try bypassing the tone controls to check the tripath chip is getting a signal.

I have a feeling tho that because of the clicking it's the TA 2020 or maybe the output diodes or inductors. Could I have cooked thru an inductor with excessive current?

I was using 4ohm car speakers, with a passive crossover, so not exactly the easiest load for the amp.

I already have another one on it's way that I ordered on Friday, but I'd like to fix this one if possible.
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Old 1st June 2009, 02:44 AM   #316
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Quote:
Originally posted by MikeHunt79
Hey guys, just got back, the Lepai works (or worked) great in the car. I say worked as it is no longer working...

I was listening to some quiet music from an MP3 player, so the volume was up high, maybe on full...

A loud song then came on after, I had around 2 seconds of very loud music and then the amp cut out...

Now all I get when unmuting the amp is a ticking noise. The ticking noise goes when it's muted.

What would be the best way of troubleshooting this? Check for DC offset on the outs?

So far I've check the op-amp is getting power, I'll try and find some small caps so I can try bypassing the tone controls to check the tripath chip is getting a signal.

I have a feeling tho that because of the clicking it's the TA 2020 or maybe the output diodes or inductors. Could I have cooked thru an inductor with excessive current?

I was using 4ohm car speakers, with a passive crossover, so not exactly the easiest load for the amp.

I already have another one on it's way that I ordered on Friday, but I'd like to fix this one if possible.

Sorry to hear that your amp is burnt. Col is correct, The voltage cannot above 13.5V.


Hoped that the TA-2020 haven't burnt.

For your new amp, you may need to add a resistor to lower down input voltage.
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Old 1st June 2009, 06:06 AM   #317
col is offline col  Australia
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Mike, have you already modded that one? I had one die on me after playing it for about 20mins, luckily I hadn't done any mods on it. I got it from "savebase" on Ebay I sent them an email and they said send it back by normal airmail. Which cost me AUD$12.50 I took a photo of the package in the post office with the stamps on it and emailed them the "proof" of sending. They wrote back and said "your replacement is in the post". It arrived this morning, very fast turn round.

Iv'e finally replaced all the 2.2uF with polyester MKT caps now.

http://pix.minirig.org.au/main.php?g2_itemId=1060


sounding superb now and Iv'e got tone controls!


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Old 1st June 2009, 08:52 AM   #318
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Quote:
Originally posted by panda360



Sorry to hear that your amp is burnt. Col is correct, The voltage cannot above 13.5V.


Hoped that the TA-2020 haven't burnt.

For your new amp, you may need to add a resistor to lower down input voltage.
Nothing looks burnt, I've even removed the heatsink and there are no black marks anywhere so I think It cold be that one of the output inductors could have gone open circuit... The chip still responds to the mute pin being on and off so I dont think the TA2020 is dead.

Perhaps if the input voltage of the car is too high then a diode in series would drop 0.5v which may be better than a resistor.

Quote:
Originally posted by col
Mike, have you already modded that one? I had one die on me after playing it for about 20mins, luckily I hadn't done any mods on it. I got it from "savebase" on Ebay I sent them an email and they said send it back by normal airmail. Which cost me AUD$12.50 I took a photo of the package in the post office with the stamps on it and emailed them the "proof" of sending. They wrote back and said "your replacement is in the post". It arrived this morning, very fast turn round.

Iv'e finally replaced all the 2.2uF with polyester MKT caps now.

http://pix.minirig.org.au/main.php?g2_itemId=1060


sounding superb now and Iv'e got tone controls!


col.
Nice work, looks like it will be quite a squeeze in the case.

I have already modded this unit, just the power input mods (cap reaplaced with a 25v 6800uF unit, inductor and diode removed) so I think I'll try to fix it.

I read thru the TA2020 datasheet again today and it has what sounds to be a helpful thing called a fault pin which can be wired up to an LED & resistor, and I'm guessing the LED will flash to show what the fault is...

I think I may also have some high current inductors, that are around 10uH, I'll try swapping these and see if anything happens.
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Old 1st June 2009, 10:58 AM   #319
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Ok, I've made some progress (I think), I'm getting 5.1v on pins 2 and 8, 1.05v on pin 4 so I think the TA2020 is ok.

I found that a zener diode is wired to pin 18 (fault pin) and I think this is somehow connected to the pin 11 (mute pin), I tried lifting the zener diode where it's connected to pin 18 and no more clicking, yet still no sound despite a small thump when unmuted.

The zener is still out at one side, and I'm now seeing pin 6 (overload) is grounded when I unmute the amp. Here's what it says in the datasheet about pin6: "A logic low indicates the input signal has overloaded the amplifier"

Is "logic low" another way of saying the pin is the same voltage as ground? I also measured from the +12v on my power source, and it was reading at -12v, so it's definately ground, so could it be a fault with the input signal?
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Old 1st June 2009, 11:59 AM   #320
col is offline col  Australia
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have you attached a LED to the fault pin? Is the light on when the amp is unmuted?

edit: try touching the fault pin to the unmute. That should reset it.

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