[seiko_citizen]

recently found a PCB board and found that this is one cmoy not working.

so for all of yours that can help please help and tell me what is wrong with the board??

am i shorting something?? if so where?

 

[Tobrew]

Your soldering looks a little rough. It looks like you might have a few solder bridges between traces. Make sure nothing is touching that shouldn,t be.

 

[Excalibur]

I don't know if you have solder bridges but it definately looks like you have some bad solder joints. Before you solder, it is a good idea to make sure the copper is clean and remove any oxidation. The copper should be bright and shiney for best soldering results. To repair your solder joints, put a generous amount of flux and resolder. This will cause the solder to bond completely with the copper. When you are done with the resoldering, clean off the flux with alcohol, flux cleaner, etc.
Lastly, recheck for solder bridges to make sure.

 

[eyevancsu]

The first thing i would do would be to trim down all of those joints/leads/spikes, some of them are extending off to the sides, this could be causing some solder bridges to occur. Reflow some new solder to some of the joints to reform them, and remove lots from the big globs. I would clean the underside of the board with a small brass bristled brush, to remove all the dry flux and any loose particles that may also be causing shorts/bridges.

It really does seem to me that pretty much all joints are touching the ones near by, meaning that it could be one big bridge/short.

Double check your resistor values with an ohm meter, and recheck polarities of your electrolytics, make sure you never applied incorrect polarities to them, since that could damage them.

One of the more important things to do is to tell us what is wrong with the amp. Do you not get any sound at all, static, distortion, clipping, inbalance, overheating, etc? That would help diagnosis (lol, medical term) to go alot smoother and in the right direction.

-ivan c.

 

[Paragon]

I would reflow all those joints or remove the solder and resolder them. When you do, make sure the solder iron tip is in contact with both the lead and the trace. Make sure you use flux, also.
Finished joints should be nice and smooth.. the solder should flow nicely between the lead and the trace copper.. these are not mashed potatoes so we do not want lumps here.. lumps = bad solder joint due to not enough heat/flux.

Take a look at http://headwize.com/ubb/showpage.php...3986&fdays=180 or search for any of sijosae's galleries to get an idea of what a joint should look like.

 

[MN Ham Phones]

Solder flows towards heat. You want the iron on one side of the lead/PCB joint and the solder on the opposite side. Heat both simultaneously, apply the solder to the *joint* not to the iron. Let the heat of the junction pull the solder into it. You do NOT dab the solder on.

Clean the board first. I brush mine with fine steel wool and wash the board after in water and mild soap.

Component leads tend to oxidize. Use an Xacto knife to carefully scrape the lead till it shines before you install it in a PCB.

Remember that some components can be heat sensitive. I use a hemostat as a heat sink to draw heat away from the body of the component when soldering them.

 

[seiko_citizen]

Thanks for all your kind replys. Can anyone tell me where to get a ohm meter?
i figured that it would be a solder ocnnection, but wanted to make sure. also before i start connecting the in/out jack the ground line is in the middle? correct? (the nice fat piece of copper across the center (pic 2))

 

[eyevancsu]

Yep, that should be it. Is that where you grounded the power caps and necessary resistors?

You can get a cheap ohm-meter or multimeter at radioshack or almost any electronics store (maybe even sears.)

-ivan

 

[Excalibur]

"i figured that it would be a solder ocnnection, but wanted to make sure."

Do not check for loose solder connections by pressing on the connection with ohm meter leads. It will appear good and as soon as you remove the meter leads, the connection will open again. Measure from the top side of the board and apply as little pressure as possible with the meter leads.

Trust me: If you want your circuit to be reliable you should reflow all the connections with flux.

From the looks of your board, the copper traces are badly oxidized and are not receptive to bond to the solder. Since it's too late to clean the copper, you need to use flux and reheat the connections.

You may get it to work without reheating with flux but I doubt that it will continue to work for long with loose connections.

 

[seiko_citizen]

Excalibur - Thanks for your advise on checking connectors, and yeah i know that that board is not of the highest quality. thinking of taking this design to a breadboard?? anu opinions?