electronics wizards "pcb" help

sandworms

need assistance from all you modders-electrical tinkering masters. by the pics posted can anyone tell what i would need to do to repair this if possible

megasat16

Where is the picture? And where it's coming from? What you want to do and what's wrong with it?

sandworms

I'm workin on that : (

disneyjoe7

Standing by ready to assist.

sandworms

http://tinypic.com/r/jadxg5/6 http://tinypic.com/r/ok5yfn/6

sandworms

try these, tiny pic isn't working for me

sandworms

http://tinypic.com/r/358axr8/6

sk1939

Ignoring the fact that all the connection joints look fried/burned....what exactly do you want from us? It looks like crossover that shorted, and somehow since the coil became unsoldered it looks like it shorted a few things...or maybe it was from an overload....did you have an amp go?

And whats with this photo, what does it have to do with circuits? Questionable Image

megasat16

It is from LSi7? The XO seems screwed. But more correctly, the inductor seems detached from the PCB. It may be happened during XO removal process but who knows?

Do you see a broken leg that is hanging on the 1st picture? There is a small area on the PCB (near the black screw and it's exposing the wood like color) where that became detached from. You need to solder it back there.

sandworms

damn , who are those guys?

sk1939

sandworms wrote: »

damn , who are those guys?

Exactly what I want to know...

disneyjoe7

It's repairable if that's what you're asking?

The foil as enough to solder it up, or you can add some 22g or so copper wire on it.

sk1939

disneyjoe7 wrote: »

It's repairable if that's what you're asking?

The foil as enough to solder it up, or you can add some 22g or so copper wire on it.

It is, but I'm still curious as to why it looks shorted/became unsoldered in the first place....did you have an amp go?

sandworms

yeh i knew it needed reattatching but i was not sure if the board would accept a true connection, it looks like the path is unsavable. but i have no clue how pcb paths work, if i resolder do i just drop onto the darker part of the board which looks like an imbedded wire? yes it's an lsi 7

Face

sk1939 wrote: »

Ignoring the fact that all the connection joints look fried/burned....

:rolleyes:

Push the lead back through the hole and solder it back up. If that doesn't work, remove the board from the binding post cup and someone here can show you where to jump the lead to. Easy fix.

sandworms

i have no history on this speaker, i bought it damaged for $20 from fleebay. i'm nervous about the scarring at the other solder joints too

megasat16

sandworms wrote: »

yeh i knew it needed reattatching but i was not sure if the board would accept a true connection, it looks like the path is unsavable. but i have no clue how pcb paths work, if i resolder do i just drop onto the darker part of the board which looks like an imbedded wire? yes it's an lsi 7

You can still solder back on. The trace (path) was half broken but there is still half left on the PCB and it looks OK to me. With careful soldering, it should works fine.

McLoki

Inductor would be pretty easy to solder back down, but as has been stated - it looks like bad things have happened at almost all the solder joints. I, for one, would be interested in a shot of the other side of the board. I bet the inductor is not the only casualty in this (and the inductor should be able to just be soldered back down - other parts may need to be replaced).

BTW - inductor repair is just push it back through the hole and solder it back down. (use enough solder to make sure the pad gets soldered back down) Flip the board over and take another pic or two before we call it good though.

Looks like a good time for a crossover upgrade in my opinion.

Michael

Face

sandworms wrote: »

i have no history on this speaker, i bought it damaged for $20 from fleebay. i'm nervous about the scarring at the other solder joints too

I've seen a few other factor Polk boards with the same marks, I wouldn't worry about it.

sk1939

McLoki wrote: »

Inductor would be pretty easy to solder back down, but as has been stated - it looks like bad things have happened at almost all the solder joints. I, for one, would be interested in a shot of the other side of the board. I bet the inductor is not the only casualty in this (and the inductor should be able to just be soldered back down - other parts may need to be replaced).

BTW - inductor repair is just push it back through the hole and solder it back down. (use enough solder to make sure the pad gets soldered back down) Flip the board over and take another pic or two before we call it good though.

Looks like a good time for a crossover upgrade in my opinion.

Michael

I assume you know the basics of soldering....but yeah if Face says it *looks* fine, then at least consider that the joints are ok. Imo however, I think that those speakers got seriously screwed, and would seriously consider testing the drivers or the whole speaker on an amp with either a protection circuit, is cheap, or doesn't mean alot to you.

megasat16

Folks, the white stuff seen on the PCB are the solder flux. The previous owner / or Polk didn't clean up the solder flux after soldering. It may be worked by someone and he didn't clean up the solder flux after working on it.

I would say Polk didn't leave the flux on like that but I might be wrong. You guys have seen the XO from LSi speakers and it's not like that, right?

sk1939

megasat16 wrote: »

Folks, the white stuff seen on the PCB are the solder flux. The previous owner / or Polk didn't clean up the solder flux after soldering. It may be worked by someone and he didn't clean up the solder flux after working on it.

I would say Polk didn't leave the flux on like that but I might be wrong. You guys have seen the XO from LSi speakers and it's not like that, right?

I don't recall flux ever being white though Is it burned flux (the ones I've always used have always been dark).

LSi 9's crossover (good)

megasat16

It's the solder flux comes in tin cans. I think whoever used to solder on this XO used that kind of flux pasted on the joints on PCB before soldering. He might even use thick core solder with that and it helps lowering the melting point. I don't know why he would do that but it's been done many times by many people before.

sk1939

megasat16 wrote: »

It's the solder flux comes in tin cans. I think whoever used to solder on this XO used that kind of flux pasted on the joints on PCB before soldering. He might even use thick core solder with that and it helps lowering the melting point. I don't know why he would do that but it's been done many times by many people before.

Supposedly it makes cleaner joints, just not in this case....dosen't that mean that this crossover has been modified?

megasat16

sk1939 wrote: »

Supposedly it makes cleaner joints, just not in this case....dosen't that mean that this crossover has been modified?

I don't know why it's been modified or worked on before but seems that way. It may probably be the subject of someone's experiment. Who knows and who cares? It just need to work after soldering the inductor back into place.

McLoki

This is what it should look like when you get it put back down....



and here is what the other side should look like... (it is only 4 screws to flip it over - I would say well worth the trouble at this point)



If you want to try a crossover upgrade - click on the LSi7 - crossovers upgraded link in my sig. It will show you what I did to upgrade the crossovers in mine...

Regardless - You got a good deal (provided the drivers work)...

sk1939

megasat16 wrote: »

I don't know why it's been modified or worked on before but seems that way. It may probably be the subject of someone's experiment. Who knows and who cares? It just need to work after soldering the inductor back into place.

That is the million dollar question does it work? Repair it and find out...

megasat16

sk1939 wrote: »

That is the million dollar question

Or may be 20 bucks!

sandworms

i'll take a couple more pics of the other side of the crossover. and i did ck the tweeter and it was making sound, not the best of sounds, but then again i had my avr sending 70hz and up, so maybe it works correctly and i'm not used to hearing a speaker with just it's tweeter. i would definetly consider the upgrade though, i just wonder if the lsi7's are a worthy investment. i haven't read that much about them.
i do know i am not the best with a solder gun and would like another party to take the job

sandworms

ps... i want to thank all the polkies who chimmed in with their invaluable advise, hopefully with a little more help i can save these poor speakers from what was a near death. if you've seen some of the speakers, from ebay or what have you, in the condition i have seen you would think there would be a law against morons coming within any proximity of quality equipment

bigaudiofanatic

Hmm Looks like it is fixable.