Need Help ... Briangt Kit LM3386 doesn't work

skappy · 3rd December 2005, 05:25 PM

Hi Everybody,
This day should have been the great day as i have just complete the construction of my first BrianGT Kit (LM3886).
I've plug a jack in a PC sound card as Input.
I've connected V+,V-, PG+ et PG- from power supply (300VA, 30 Volts & 5 Amps) to Main card ...
i've connected the mlain card to loudspeaker but nothing happens ...

Where should i search ?
Power supply works as i have 41 Volts on the main card

Thank you very much for your ideas

odysseybmx414 · 3rd December 2005, 05:37 PM

nothing happens? maybe the plug hooked to your pc soundcard is in the wrong jack. because usually when theres something wrong with an amp it will hum or "motorboat" or do something odd

odysseybmx414 · 3rd December 2005, 05:39 PM

did you try a diff source such as dvd player or cd player?

skappy · 3rd December 2005, 05:45 PM

the pc sound card is OK, i've checked it with a another amp...
I have test the Amp with another source (portable cd player) but nothing happens ...

I would like to add that i have not use any potentiometer between sound source and the amp but as the volume was set by the Pc it should not be a problem ...

carlosfm · 3rd December 2005, 11:20 PM

Are you using a heatsink?

neutron7 · 4th December 2005, 02:06 AM

can u attach a picture of the board and connections?

john65b · 4th December 2005, 11:29 AM

Are you suing BOTH Rectifier Circiuts with Dual Secondaries (ie, do you have two hots and two neutral legs coming form your transformer correctly attached to the PS Board?)

If you have two hots and a single Center Tap, you need to use only One rectifier circuit. Look into how the Transformer is wired for ONE Rectifier circuit on the LM3876.pdf instructions, as it does not go into this variance on the LM3886.pdf instructions.

I wired it up "incorrectly" on mine and still showed +40V -40V unattached to the amp board, but when amp boards connected, I kept blowing fuses neutral fuse (I had dual fuses on Nuetral and hot)... I could not get mine to work until I removed the 4 inner diodes and jumpered them per the LM3876.pdf.

Works great now.

My 2 cents

skappy · 4th December 2005, 04:48 PM

Hi Everybody,
thank you very mucj for your attention and your help ...
yes , i have used a Heatsink for the LM3886
i think that my connections to the power supply is correct but i have to add that i've only plug only one way , the other one is not connected and i have observed tyhat in one case, i have something like 2 volts at the loudspeaker output, and when i change the power plug to the other way i have 0.4 volts ...
I can't undertstand

I've joined somes photos in the next messages if ithey could help...

Thank you very much for your help

skappy · 4th December 2005, 04:51 PM

1.

skappy · 4th December 2005, 04:56 PM

2.

3rd December 2005, 05:25 PM	#1
skappy diyAudio Member Join Date: Jan 2004 Location: France	Need Help ... Briangt Kit LM3386 doesn't work Hi Everybody, This day should have been the great day as i have just complete the construction of my first BrianGT Kit (LM3886). I've plug a jack in a PC sound card as Input. I've connected V+,V-, PG+ et PG- from power supply (300VA, 30 Volts & 5 Amps) to Main card ... i've connected the mlain card to loudspeaker but nothing happens ... Where should i search ? Power supply works as i have 41 Volts on the main card Thank you very much for your ideas

3rd December 2005, 11:20 PM	#5
carlosfm Banned Join Date: Mar 2003 Location: Lisbon, Portugal	Innocent question ahead Are you using a heatsink?

4th December 2005, 11:29 AM	#7
john65b diyAudio Member Join Date: Jan 2005 Location: Chicago	I bet... Are you suing BOTH Rectifier Circiuts with Dual Secondaries (ie, do you have two hots and two neutral legs coming form your transformer correctly attached to the PS Board?) If you have two hots and a single Center Tap, you need to use only One rectifier circuit. Look into how the Transformer is wired for ONE Rectifier circuit on the LM3876.pdf instructions, as it does not go into this variance on the LM3886.pdf instructions. I wired it up "incorrectly" on mine and still showed +40V -40V unattached to the amp board, but when amp boards connected, I kept blowing fuses neutral fuse (I had dual fuses on Nuetral and hot)... I could not get mine to work until I removed the 4 inner diodes and jumpered them per the LM3876.pdf. Works great now. My 2 cents

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3rd December 2005, 05:37 PM	#2
odysseybmx414 diyAudio Member Join Date: Feb 2005 Location: Watertown, NY	nothing happens? maybe the plug hooked to your pc soundcard is in the wrong jack. because usually when theres something wrong with an amp it will hum or "motorboat" or do something odd

3rd December 2005, 05:39 PM	#3
odysseybmx414 diyAudio Member Join Date: Feb 2005 Location: Watertown, NY	did you try a diff source such as dvd player or cd player?

3rd December 2005, 05:45 PM	#4
skappy diyAudio Member Join Date: Jan 2004 Location: France	the pc sound card is OK, i've checked it with a another amp... I have test the Amp with another source (portable cd player) but nothing happens ... I would like to add that i have not use any potentiometer between sound source and the amp but as the volume was set by the Pc it should not be a problem ...

4th December 2005, 02:06 AM	#6
neutron7 diyAudio Member Join Date: Dec 2003 Location: Toronto Canada	can u attach a picture of the board and connections?

4th December 2005, 04:48 PM	#8
skappy diyAudio Member Join Date: Jan 2004 Location: France	Hi Everybody, thank you very mucj for your attention and your help ... yes , i have used a Heatsink for the LM3886 i think that my connections to the power supply is correct but i have to add that i've only plug only one way , the other one is not connected and i have observed tyhat in one case, i have something like 2 volts at the loudspeaker output, and when i change the power plug to the other way i have 0.4 volts ... I can't undertstand I've joined somes photos in the next messages if ithey could help... Thank you very much for your help

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