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Old 7th July 2011, 03:16 PM   #821
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@sofaspud: Thanks for the response. Based on your ideas, I know I don't want to learn that much about this just to get this amp working. Will take your advice and simply get a new amp. Boom zap problem solved. Thanks!
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Old 7th July 2011, 04:44 PM   #822
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Hey! I plugged it into a 12v wall wart, and it works! Beautiful! Great sound! It's beyond my understanding, but I don't care, cause it works. Lepai 2020+.
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Old 8th July 2011, 12:58 PM   #823
pkozul is offline pkozul  Australia
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HI there,

I ordered a replacement TA2020 IC... still waiting for it to arrive...

In the meantime, I was wondering whether it's possible to find a suitable socket for the IC to allow for easy replacement in case of a future failure... saves having to desolder the old chip, and solder on the new one.. each time (hopefully never again... but you never know!)

In the datasheet, it mentions: 32-pin SSIP package

Not sure if that helps. Anyone have any ideas whether it's possible to find a suitable socket for the IC?

Cheers,
Pete
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Old 8th July 2011, 02:14 PM   #824
gychang is offline gychang  United States
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Quote:
Originally Posted by sofaspud View Post
I just received my Lepai LP-2020A+ from PE. Gonna do some more listening and "electron exercising" before opening it up.
I have 2 sitting on my desk, I am interested in improving the sound, so I am waiting for a guru to guide me. Would appreciate your input and have the solder gun warmed up...

For a guys like me picture-guide work wonders...
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Old 8th July 2011, 06:59 PM   #825
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Quote:
In the meantime, I was wondering whether it's possible to find a suitable socket for the IC
Those acronyms again... I think SSIP is Staggered Single In-line Package. I am not aware of a socket for these. You could possibly make one by using two single-row headers. Sometimes sockets are a definite bad idea, though, and this may be one of those times. To replace the bad chip, just cut the leads of the chip. Then it's pretty easy to heat the remaining legs and push them out of the holes. Clear the holes of solder using a solder sucker or by melting the solder and then giving the board a light tap on the benchtop.
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Old 8th July 2011, 07:18 PM   #826
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Quote:
I am interested in improving the sound,
I don't consider myself a guru. I have been doing plenty of listening. I have my Lepai connected to a pair of modified RS Nova-10 speakers. The passive radiators have been replaced with 8" full-range drivers, with their own small chip amp. I'm also using a small sub and the sound is surprisingly good. Without the sub the Lepai seems to lack low-frequency power. It'd be nice to stretch another octave or so out of the low end. I've been busy lately (need to leave now to go meet with a customer) but I'm sure I have some caps and op amps on hand. That's where I plan to start unless I find something else when I get my amp opened. More to follow.
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Old 9th July 2011, 05:13 AM   #827
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Unfortunately the LP2020A+ I have is identical to the pic of post #751 and not like the schematic of post #736. In the pic (just south of the RCA inputs) R36 & R37 are 1k series resistors and R34 & R35 are 10k resistors to ground. C30 & C31 are 1uF input coupling caps. From there the signal goes to the 20k potentiometer then right to the op amps, so it looks like at least part of the flaky tone circuit could be caused by the bypass implementation. Hopefully the circuitry from there on is close enough to the posted schematic.
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Old 9th July 2011, 08:15 PM   #828
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I wasn't very familiar with the 4558 op amp, but everything I see (and hear) says this thing is just a glorified 1458, ie no way suitable for audio. That's the first thing I'm going to address on my Lepai. I have some SMT LM833s in stock and that's what I'll use. Not my first choice but they are at hand. Hopefully that will clear up my main issue, which is the midrange distortion I get at higher volume. My speakers lean toward the bright side anyway, and that distortion makes me want to run for cover. Horrendous!
If you own a soldering iron, you can do this too. Just cut the legs of the 4558 with an Exacto. The parts remaining will probably stick to the iron tip, making removal easy. Then clean the pads with desoldering braid. Put a small amount of solder on one pad, then use that pad to align the new chip and tack it down. Then solder the rest of the leads using plenty of flux.
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Old 11th July 2011, 06:42 PM   #829
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Quote:
Originally Posted by Sigrm View Post
What happens if the voltage drops below 8,5V? Is it possible to change this to something like 11,5V to protect a SLA battery?

Another question:
Can the amp get damaged if I run it with only one output channel driving my speakers?

Thanks in advance!
OK, I connected mine to a variable power supply, if the supply voltage goes below about 8.5V the amp is muted and the fault pin goes high (I have an LED connected to the fault pin). When the voltage goes above 8.5V the amp comes back on and the fault pin goes low.

I can't think of any reason why running only one channel should damage the amp. If your using it for a sub woofer, you could use a dual voice coil speaker and connect both channels to increase the output.
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Old 17th July 2011, 07:27 PM   #830
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Quote:
Originally Posted by karosa View Post
Only agdiode in the middle in front of the IC, can't miss it.
Don't know when I'll open the amp up ain to take pictures.
Here's a pic of the removed diode though:
http://img815.imageshack.us/img815/4665/diode.jpg
Any chance of getting a picture?


Quote:
Originally Posted by ccl View Post
There seems to be a confusion of what part needs to be removed to prevent the ticking death of these amps. There are two parts that looks similar on the board. One is a 14v zener and the other is a 1n4148 switching diode. It's the diode that needs to be removed not the zener. The zener is part of the over voltage protection circuit, you shouldn't remove that.
I am unable(/an idiot) to read those layouts, would it be possible to help out a noob and show a real picture?

I'm planning to run this of a 8 pack AA batteries - any chance I will kill it? (ie. go over 14V?)
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