Miguel Font design GC !!! Please help.....

safetyman · 5th February 2006, 02:42 PM

Hi guys, I am trying to help out a friend with his project. Both of us are noobs, so right now, it's a case of the blind leading the blind.

He downloaded some files from a site of which he has forgotten to bookmark and can't find it again. He started to etch the PCB for this LM3886 GC and after completing it, he asked my help to digest the schematics and order the parts for him. On the board there is a capacitor marked C1. In the schematics, there is no such capacitor shown.

Anyone of you good guys may have experience and knowledge to assist the project to go forward. Presently, it's stalled bcoz of this. I am attaching the board pdf. I hope someone here can assist my friend to continue his project. Thanks.

safetyman · 5th February 2006, 02:50 PM

Schematics for the amp section....

safetyman · 5th February 2006, 02:54 PM

Schematics for the PSU......both the sections semms to be onboard. I could be wrong as I have never decipher schematics b4.

Any help will be most appreciated....

tiltedhalo · 5th February 2006, 03:37 PM

Cin1 and Cin on the PC board layout are both 2.2uf poly caps and look like Cin1? and C2? on the schemactic. The first two caps after the signal input, these are your coupling caps there to prevent DC from previous stage. Dont understand why useing two in parellel one with a value of 1uf to 4.7uf with the 22K resistor would work fine?????

safetyman · 6th February 2006, 05:41 AM

tiltedhalo, thanks for the reply, but I know nothing about circuit design so cannot comment until the GC gets powered up, if it ever does.

The missing value is the C1 located in the middle of the board where there is a GND next to it, as it doesn't seem to appear in the schematics. Any ideas or suggestions?

dhengkoel · 9th February 2006, 09:17 AM

c1 is for alternate choice if you use one bipolar capacitor, about 50uF, to replace two polar capacitor c1a & c1b.

regards:
ragil.hastomo

safetyman · 9th February 2006, 03:18 PM

Thanks dhengk, this seems helpful. I was just going thru the schematics and the pdf and somehow I sense that something is wrong. The pin 2 of the LM3886 seems to be connected to the wrong place on the pdf board, and the schematics seems to be right. Could anyone help verify this?

Thanks.

5th February 2006, 03:37 PM	#4
tiltedhalo diyAudio Member Join Date: Sep 2005	GC help Cin1 and Cin on the PC board layout are both 2.2uf poly caps and look like Cin1? and C2? on the schemactic. The first two caps after the signal input, these are your coupling caps there to prevent DC from previous stage. Dont understand why useing two in parellel one with a value of 1uf to 4.7uf with the 22K resistor would work fine?????

6th February 2006, 05:41 AM	#5
safetyman diyAudio Member Join Date: Jan 2004 Location: Terengganu, Malaysia	tiltedhalo, thanks for the reply, but I know nothing about circuit design so cannot comment until the GC gets powered up, if it ever does. The missing value is the C1 located in the middle of the board where there is a GND next to it, as it doesn't seem to appear in the schematics. Any ideas or suggestions? __________________ Shehzad Aleph 3 - Diehard fan

9th February 2006, 09:17 AM	#6
dhengkoel diyAudio Member Join Date: Nov 2001 Location: Sidoarjo, the delta city	c1 is for alternate choice if you use one bipolar capacitor, about 50uF, to replace two polar capacitor c1a & c1b. regards: ragil.hastomo __________________ :: The last but not least ::

9th February 2006, 03:18 PM	#7
safetyman diyAudio Member Join Date: Jan 2004 Location: Terengganu, Malaysia	Thanks dhengk, this seems helpful. I was just going thru the schematics and the pdf and somehow I sense that something is wrong. The pin 2 of the LM3886 seems to be connected to the wrong place on the pdf board, and the schematics seems to be right. Could anyone help verify this? Thanks. __________________ Shehzad Aleph 3 - Diehard fan

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