scott_jcp said:
Components:
Board pic:
http://www.briangt.com/gallery/lm3886amp/3886_019?full=1
Amp board:
R1 - input resistor = 1k (2 - black on the resistors packed)
R2 and Rf - input-to-ground resistor = 22.1k (4 - uncolored)
R3 - feedback-to-ground resistor = 681 (2 - blue)
Rm - mute resistor = 10k (2 - red)
picture of 2 ways to wire feedback resistor:
http://www.briangt.com/gallery/lm3886amp/3886_037
with and without the feedback capacitor, notice the resistor placement
C1,C2,Cm - 100uf
C3,C4,Cz - 0.1uf
Ci - 47uf
Power supply board:
R1,R2 - 1 ohm resistors for snubber network
R3,R4 - 2.2k bleeder resistors for power supply caps (mount on bottom)
R5 - 10k or 22k resistor for LED (10k might be too bright, so try 22k to lower the current supplying the LED to reduce brightness)
C1-C4 - snubber caps = 0.1uf
C5,C6 - power supply caps = 10,000uf
C7 - 10uf cap for LED (extra included in bag with diodes)
D1-D8 - power supply diodes = MUR860
I am working on a manual now, and will try to finish it soon.
--
Brian
scott_jcp said:
Thanks Brian for the post! I was going to ask the exact same question but found this post in the search. Remarkable timing on Scott's part! May I suggest you post the color code on your web page?
Scott-
Rchdn TX... I'm up in McKinney. Want to meet up for amp listening sessions one day?
Thanks,
Troy
dsavitsk said:
Only Brian knows the color coding of the resistors he shipped. (I assume he has a master plan with the markers
).The resistors he shipped are NOT the factory spec'ed values so proper placement is a guesstimate until he confirms. (Which he did).
I think Scott's original post was directed towards Brian even though he does not state so.
PS, I have an ORIGINAL Fluke 87 and the 10k probe I bought myself for graduation back in '87. I use it at LEAST every other day and it's still in "close to mint" condition.
Look at the pictures posted for the power supply. Gold stripe with 3 red stripes go on the bottom (R3 and R4). Black stripe with 2 gold stripes goes on the top (R1 and R2). My guess on the led is longer leg goes where arrow is pointing marked on board. On the led resistors they are so small even with my magnifying glass I can't read them. I see though that on has a red tab and the other does not so this must mean something. Any corrections anyone.
Cheers,
Pete
Cheers,
Pete
Quick question so I can finish out my power supply board. On the old PS boards they where marked AC1 N AC1 H AC2 N and AC2 H. On the new snubber PS they are marked AC1 and AC1 (with line over top) same for AC2 which is Hot and which is Neutral. On the led is it the shorter leg(cathode) that goes on the hole that the arrow is pointing to on the board. Thanks
budwiser said:
Well the pwr supply in is AC so it doesn't matter since it is built for dual secondaries.
As for the LED I did not install mine so I will let Brian answer that one. However, if you have the resistor installed, then you can pwr up the board and just try it both ways to see. One way it will work the other it won't. It will not damage the LED **IF** the voltage dropping resistor is installed.
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