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#1 Juicyv

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Posted 02 December 2017 - 01:02 PM

I recently got my hands on a 2nd hand lasonic i931bt that has never been used, it's a US import, there's a switch on the back to change it from 110v to 240v, I set it to 240v bought a plug adapter and plugged it in, it switched on all the Led's are working but there's no sound.
Any advice would be appreciated

#2 Transistorized

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Posted 02 December 2017 - 03:29 PM

Have you tried the headphone jack to see if it works? If not try the mic input with a microphone and turn up the mic volume to test the Amp. The Mic input bypasses all the radio and BT circuitry and goes right to the amp when the mic volume is increased. If you get no sound on or out of any of these procedures then it's bad news. At that point IMO you most likely have a faulty output chip (has heat sink on it). Either way, at that point it would indicate an internal circuit failure. These newer Lasonics are not user repairable. They are mostly comprised of IC chips that are specifically made for that board and model. Even the factory would not troubleshoot. They would replace the entire input output board.

 

Good Luck



#3 Juicyv

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Posted 02 December 2017 - 03:39 PM

Great, thanks for that I'll give them a go and keep my fingers crossed 🤞

#4 Juicyv

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Posted 02 December 2017 - 04:08 PM

Just tried it with the headphones in and it works, sorry to sound dumb but what does that mean? Where do I go from here?
Thanks in advance

#5 Transistorized

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Posted 03 December 2017 - 09:49 AM

At that point I would open her up and check the cable that leaves the main board to the speakers. Wiggle it and/or make sure it didn't come loose. Also if someone tried to pull the speaker wire harness off the board, sometimes on these Chinese boards the whole collar pulls off the board leaving only the pins sticking up. In which case if the diagram is not silk screened onto the board it can be installed or pressed back on backwards or pins can get broken. For the speaker connection you most likely have a 3 pin harness configuration. GND / L+ / R+ if you get this configuration backwards it would not play at all because there is no complete circuit to the speakers.

 

So check the speaker output harness for correct positioning and make sure it is connected. If this seems okay then my next suspect would be the headphone jack itself. When headphones are inserted it removes / kills the feed to the main speakers inside. I would think it highly unusual however it is possible that this headphone jack could have a bent contact that (when the headphones are removed) is preventing the connection required to drive the main speakers from the Amp chip.



#6 Juicyv

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Posted 06 December 2017 - 03:49 PM

Thanks transistorized for all your help, finally got a chance to take the back off and got it working, sorry I'm not very technical but it might be what you said was the speaker output harness, it was a small white plug, that the speaker wires go into, that wasn't in it's socket.
An easy fix!!
Thanks again

#7 Transistorized

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Posted 08 December 2017 - 04:41 PM

That's good news because after these checks if it still didn't work it would be a slippery slope. Now rock that thing around the house and be proud  :rock:



#8 JVC Floyd

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Posted 08 December 2017 - 04:51 PM

Hell my new i931 I had to stretch the springs on the battery compartment because it wouldn't power up on batteries out of the box , wtf man .

#9 jimmyjimmy19702010

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Posted 08 December 2017 - 05:07 PM

Thanks transistorized for all your help, finally got a chance to take the back off and got it working, sorry I'm not very technical but it might be what you said was the speaker output harness, it was a small white plug, that the speaker wires go into, that wasn't in it's socket.
An easy fix!!
Thanks again

I think that’s the first time the ‘check for loose wires’ advice actually worked! :-)

Congrats,

James.... :-)

#10 Juicyv

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Posted 09 December 2017 - 01:49 PM

Thanks all, its never been used so it makes me wonder how the wires could have become detached! it's a present for Christmas from my wife so she's made me put it away until the 25th 😔😭,