Help a beginer build a nice amp!

[goneXC]

I can you see you bridged your pins on the undersid, but I dont get it though... It looks like you only have two solder bridges? I would think you would need four?

The pins actually labelled 1-4 on the inside are the positive. The pins on the edge of the board are -ve and common so don't need bridging.

[Lasse94]

The pins actually labelled 1-4 on the inside are the positive. The pins on the edge of the board are -ve and common so don't need bridging.

Oh okay! I'll just do what you did!

http://imageshack.us/photo/my-images/843/imag0301f.jpg/
Progress so far!

I fixed and tested all the diodes, i had 3 that didnt work, they are now fixed!! (used the diode setting on my multimeter)

I tested the outputs by putting one wire in the negative power input slot and then going through the outputs.
The results (with multimeter on 200k ohm) :
1+=nothing
1-=56.1
2-=56.8
2+=57.1
3+=57.4
3-=57.1
4-=39.3
4+=56.3

EDIT!! : So apparently i dont not have my multimeter set on 200k ohm. BUT on 200k its practically the same. 1+ is not working (spotted a bad solder, going to fix that) and 4 is lower than the others.


I'm not sure what this means, but something is wrong in 1+ and 4-

http://imageshack.us/photo/my-images/266/imag0302x.jpg/
I went shopping!
Came home with a dual 100k ohm potentiometer, a switch and some of that braid (never tried it, it AWESOME!)

[goneXC]

Yes that braid is really good stuff. Some hi res photos at: http://www.flickr.com/photos/1064425...n/photostream/ and http://www.flickr.com/photos/1064425...n/photostream/

[Lasse94]

Yes that braid is really good stuff. Some hi res photos at: http://www.flickr.com/photos/1064425...n/photostream/ and http://www.flickr.com/photos/1064425...n/photostream/

Thanks alot for those nice pictures. I don't think I have time to assemble the rest of the amp today, but i will try to do it on thursday.

Do you know any simple ways to test your amp without the chip installed? I used the diode test function and tested the lines from the holes for the chip and down to the outputs. They all worked.

When I try to do the same bt with the multimeter set on ohm, I get strange results. The display reads some random number and then during 1 second it drops to 0.00. WTF?

[Lasse94]

I'm back!

So i managed to mount the rest of the components before I have to go to work (in 37 minutes).

http://imageshack.us/photo/my-images...mag0305cg.jpg/

You can see my input solution.

http://imageshack.us/photo/my-images/831/imag0306k.jpg/

close-up of how i bridged the input

http://imageshack.us/photo/my-images/32/imag0307r.jpg/

close up on chip solder. im unsure of some of them, but I ran out of solder ("¤/#"%&#"%#"¤=!!!!!!!!!!)

tomorrow i'm going to find a heatsink and some thermal compound and then its time for testing!

[goneXC]

You can test chip leads to pads with continuity tester. Also check to see no shorts onto nearby capacitors. ESSENTIAL to put inline fuse on the +ve supply when testing. I find just attaching the chip to the back of the metal case is quite adequate for a heat sink.

[Lasse94]

You can test chip leads to pads with continuity tester. Also check to see no shorts onto nearby capacitors. ESSENTIAL to put inline fuse on the +ve supply when testing. I find just attaching the chip to the back of the metal case is quite adequate for a heat sink.

I'm going to test all the pins as soon as I come home from school. I do not yet have a case for the amp so I will have to find some piece of aluminium or something.

You say i will have to have a fuse on +ve. Could you tell me what kind of fuse i need? Maybe some pictures of your setup? and is this only when testing?

[goneXC]

I can't remember exactly what I used - I think it was a 500mA quick blow fuse 20mm glass type with an ordinary in line holder. Once tested and OK change it for a 3-4A fuse. Good luck - I will be offline for 3 weeks as from tomorrow.

[Lasse94]

IM BACK!!

I checked every solder on the board and everything is now perfect (or close).
I connected power and the amp started up fine. I then tested the outputs one at a time and they all worked!! Sound was very wierd though! 3 outputs had no bass and the last only had bass.

I am atm using a way too small power supply (18volts 2.5 amps).
the speakers are 3-ways 100 watt. (quite large) Is the problem my way too tiny power supply?

ALSO the awake led was very dimm (not bright). maybe because of lag of power?

I need you now more than ever guys!!

-Lasse

[gnome]

That power supply is ample. The fact that you got sound out from all channels is good news, but there shouldn't be any apparent filtering going on, did you give the board a good scrub with propanol?