[Ruffy]

Well I flubbed my build. When you turn the amp on you hear a loud continuous thumb/click/popping sound thats very powerfull and kindof heavy on the bass end of the scale. The pot can control how loud it gets. You do hear some music faintly. But if you turn the amp off you hear music clearly and you can control its volume via pot(I'm guessing thats just in its design)

I've double and triple checked all my connections while building
I've tried using 9, 12, 13, 16, 18vdc wallwarts all wired properly
I've tried 9 and 18v Battery power
I've tried changing resistors to set gain from 3 to 5 to 11

Dont know what to do. At this point Im thinking its one of these issues
The buffer is dead, Died while soldering or static shock
The TLE Transistor is dead Died while soldering or static shock

The op amps "should" be ok since I socketed them and didnt put them in place till the very last minute. but since then I've removed and replaced them again so who knows.

I used matched resistors metal film. I used dual .47uf and dual 470uf caps

Anyway onto the pics. Terrible soldering job. It was alot better before I started removing resistors and such. right now there are several unclipped resistors floating all over the place on the board.







at the bottom of the board I have a solder bridge(that shouldnt matter since those two strips are jumped at several places. In any case I tried to cut the bridge but I cant seem to do it. I've tried solder braid to no avail.


For power switch im going Positive lead from power jack to switch, switch to circuit board.

No led is in place.


Please help.

I'm liable to strip everything I can and try a Cmoy from whats salvagable if i cant get this working. I have a cheap Multimeter. Anything I could check?






My previous thread has the layout I used and parts list

http://www5.head-fi.org/forums/showthread.php?t=135742

 

[Ruffy]

remember pics are thumbnails so click them to see full size

 

[Ruffy]

probing around with my crappy multimeter

While on I get 24 volts from the V+ V- pads. The wallwart running it is 16.4v at the jack

While checking 18k resistors that control the Gain, I get 5kohms from them. Un socket them and test and they back to 18k. Is this the Gain that its showing me?(technically it should be around 5)

Nothing gets hot while its on.

 

[Edwood]

You should definitely get a DMM with a continuity check feature to see if there truly is conductivity bewteen parts that shouldn't be.

Your bottom pic showing the underside soldering, check the middle ground area towards the bottom. Looks like it is bridging to the right for sure.

-Ed

 

[nikongod]

i got it.

it looks like you joined the input cap with the output line.

of course i could be wrong, but i dont see any seperate "line" or pad for the input cap.

edit: i also agree with edwood, there appears to be a bridge fromt he ground-line to a pin on the chip.

 

[Ruffy]

Quote:

Originally Posted by nikongod i got it. it looks like you joined the input cap with the output "buss" line. of course i could be wrong, but i dont see any seperate "line" or pad for the input cap.

that might actually be it!

I just laid down on giant strip since large portions under the input caps were all linked. letme fix and try

(glares at pic here)
http://www5.head-fi.org/forums/showthread.php?t=135742

 

[Ruffy]

well nikongod you truly are a god
that fixed it!

Listening to my crappy cans right now letting it warm up. But all is working fine

I do kindof wish I still had the ability to bypass the amp all together with a flick of the switch(Turn it off you still hear the source just unamped)

Im guessing thats what the bypass switches are for on higher end diy amps

In any case Thank you Thank You Thank You Thank You Thank you thank you.

Now I gotta fix the resistors and finish the enclosure!

 

[Edwood]

Woohoo!

Good call, Nikongod.

-Ed

 

[nikongod]

well, im glad ot hear that all went off well.

every now and then i get one right

as punishment for this, it seems that my recable on my k-240's pulled out (i didnt use good strain releif....) so i guess weall know what im doing tonight.

 

[Ruffy]

Quote:

Originally Posted by nikongod well, im glad ot hear that all went off well. every now and then i get one right as punishment for this, it seems that my recable on my k-240's pulled out (i didnt use good strain releif....) so i guess weall know what im doing tonight.

Truly Nikongod I love you! I was sitting there tracing everything possible but always overlooked that.

All is working well, damn this thing has some kick to it. My measly AKG 26P cans sound alot better with it. Bass is alot better, mids are more pronounced. I feel satisfied for now(Not really. Now I want the Senn 480's.... Or maybe something better and a pimeta or ppa or m3....)
I forsee a very empty wallet in my short future

Now for one last question. Someone recheck my math for me.

I'm calculating the resistor needed for an LED.

16-18vdc In
LED is 5v 100mA

My math has me at a 110 to 130ohms resistor. That sound right?

 

[nikongod]

dont jump for the pimetta/ppa/m3 untill you have opamp rolled the a-47.

i like using diferent opamps in the 2 positions, i think the "sound effects" from mixing brands (and within a brand but difeerent chips...) are very nice. thee is LOTS of room to experiment here.

just be sure not to put a non-unity-gain stable amp in the "pseudo buffer" position. that one had me troubleshooting my a-47 for a good long time. also my ballanced amp.

argh, this thread (and your layout, i like that ALOT) make me want to build another a-47. or some similar variant.

 

[Ruffy]

Quote:

Originally Posted by nikongod dont jump for the pimetta/ppa/m3 untill you have opamp rolled the a-47. i like using diferent opamps in the 2 positions, i think the "sound effects" from mixing brands (and within a brand but difeerent chips...) are very nice. thee is LOTS of room to experiment here. just be sure not to put a non-unity-gain stable amp in the "pseudo buffer" position. that one had me troubleshooting my a-47 for a good long time. also my ballanced amp. argh, this thread (and your layout, i like that ALOT) make me want to build another a-47. or some similar variant.

hehe I kindof want to build another one too. Or a Cmoy or Cmoy 2. Something cheap is doable as I have resistors and caps up the *#$% now.

Maybe I'll do a mini cmoy for a pocket amp.

I can say one thing, I learned alot. I dont understand the circuit but damnit, I can sorta solder again. It helps to have a temp controlled station.

If I were to redo a A47 id prob spend a good ammount of time working out a better breadboard layout. And probably have most of the connections detachable via use of headers or similar.

 

[Porksoda]

Quote:

Originally Posted by Ruffy Truly Nikongod I love you! I was sitting there tracing everything possible but always overlooked that. All is working well, damn this thing has some kick to it. My measly AKG 26P cans sound alot better with it. Bass is alot better, mids are more pronounced. I feel satisfied for now(Not really. Now I want the Senn 480's.... Or maybe something better and a pimeta or ppa or m3....) I forsee a very empty wallet in my short future Now for one last question. Someone recheck my math for me. I'm calculating the resistor needed for an LED. 16-18vdc In LED is 5v 100mA My math has me at a 110 to 130ohms resistor. That sound right?

Are you sure that LED runs at 100mA? That is a really serious ammount of power! Usually LEDs run at about 10mA w/ 1.5V across them. Assuming your specs for the LED requirements are right, your math is correct.

Do you have a datasheet or anything for this LED? I would be curious to take a look at it...

 

[Ruffy]

Quote:

Originally Posted by Porksoda Are you sure that LED runs at 100mA? That is a really serious ammount of power! Usually LEDs run at about 10mA w/ 1.5V across them. Assuming your specs for the LED requirements are right, your math is correct. Do you have a datasheet or anything for this LED? I would be curious to take a look at it...

high output hi intensity blue LED

Intnsity 10,000 mcd
Directivity 15 degrees
Operating time 100k Hours
Wave Length 470nm
IF 30mA
IFP 100mA
VR 5V
PD 120mW
Topr. -30 Degree to +100 Degree


Thats what it says
Model TT7802CP
Made by Coast LED Lenser

 

[nikongod]

that led will be INSANELY bright at full power. like small flashlight bright.