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loud humming sound

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ostrichmilkman View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ostrichmilkman Quote  Post ReplyReply Direct Link To This Post Posted: 08 March 2018 at 2:18am
or tell me where i can buy a pcb with that function or just what to search for. 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote studio45 Quote  Post ReplyReply Direct Link To This Post Posted: 09 March 2018 at 2:49pm
I don't think you will need any extra circuitry to use your amp and battery charger at the same time. Your amp board should have enough power supply filtering to get rid of any noise caused by the battery charger. 
If you do experience noise, I'd probably try adding some simple passive filtering to the power lines; the noise is likely to originate in the high frequency switching of the charger, so put some small capacitors (0.1uf) in parallel with the power at the amp board; if that doesn't give enough improvement try small value high current inductors in series, or wrapping a few turns of each conductor around a ferrite ring. If the noise is low frequency (50/60hz hum) you will need larger values of capacitor/inductor to filter it.

If none of that works, try a different amp board and/or charger.... 
Studio45 - Repairs & Building Commotion Soundsystem -Mobile PA
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Post Options Post Options   Thanks (0) Thanks(0)   Quote slaz Quote  Post ReplyReply Direct Link To This Post Posted: 09 March 2018 at 5:16pm
Originally posted by ostrichmilkman ostrichmilkman wrote:

can anyone tell me what size barrel connector the lepai ta2020 uses ? need to buy a male and a female so i can run it from a wall socket whilst the battery is charging.  



5.5mm outer, 2.1mm inner - the most common type.



REMEMBER....POLITICIANS AND DIAPERS SHOULD BE CHANGED OFTEN AND FOR THE SAME REASON
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ostrichmilkman View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ostrichmilkman Quote  Post ReplyReply Direct Link To This Post Posted: 16 March 2018 at 5:51am
all the bits are here !!!
 
gave everything a test run and she sounds good. looks like i got lucky with the amp this time

happy days 


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Post Options Post Options   Thanks (0) Thanks(0)   Quote slaz Quote  Post ReplyReply Direct Link To This Post Posted: 17 March 2018 at 3:42am
Yeah well those Lepai (Lepy now) 2020 amplifiers are actually very handy little things.
Ain't no Powersoft K20 .... but they just _work_ for little battery systems.

One of mine has survived a couple of trips to the West Indies where it got left out in tropical sun (when I got drunk and forgot it was there), splashed with sea water from trips in small boats,
sand blown at it on windy beaches, thraped by idiots more drunk than me whacking up the bass knob .... all sorts of abuse - and it still works :-)

One thing to watch out for is .... the blue light around the volume knob will still come on even when the battery volts  are too low to power the amp, so don't go assuming its dead. For that reason, I'd get a dremel to it and fit one of those very low consumption cheapo little digital voltmeters into it.





Edited by slaz - 17 March 2018 at 4:04am
REMEMBER....POLITICIANS AND DIAPERS SHOULD BE CHANGED OFTEN AND FOR THE SAME REASON
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Post Options Post Options   Thanks (0) Thanks(0)   Quote CHED Quote  Post ReplyReply Direct Link To This Post Posted: 20 March 2018 at 6:50pm
hi bud, idont suppose you have a battery charger connected to the battery while running amp, do you ? your just running the battery free standing and its at least 11.9 volts ?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote slaz Quote  Post ReplyReply Direct Link To This Post Posted: 21 March 2018 at 11:06am
I don't think its wise to have a Lepai 2020 (or similar) amp connected to battery while its charging.

Towards the end of the cycle, the "net" voltage across the batt/amp will get to ~14.6/14.7V - which could well cause the escape of magic smoke from the amp.

REMEMBER....POLITICIANS AND DIAPERS SHOULD BE CHANGED OFTEN AND FOR THE SAME REASON
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ostrichmilkman Quote  Post ReplyReply Direct Link To This Post Posted: 22 March 2018 at 5:14am
got it all running and its working sweet. my mates well chuffed with it. for the price you pay those little amps are amazing, shame there not bridgeable but with the right speakers they get more than loud enough to annoy the neighboors. i haven't tried charging the battery while running the amp yet so no idea if ill get any interference, but from what you said and after a bit more googling i gathered it wasn't as much of an issue as i've been led to believe in the past. Im pretty sure the voltage will be ok i've seen reports on different forums/threads of people running them on 15v power supplies and getting gains in output and sq and not blowing up but ill double check my memories are right before i go and blow the thing up. and yeah ive  fitted a volt meter and given him strict instructions to check it and not let it drop below 12.2v etc
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ostrichmilkman View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ostrichmilkman Quote  Post ReplyReply Direct Link To This Post Posted: 22 March 2018 at 5:19am
nah seems your right about the voltage slaz, just checked the data sheet an its 14.6 max, must be another one of those misshapen pieces in my soup of memories
 
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