L100 Crossover Problems...Help!

[seanbreaux]

I recently was given a pair of L100's, though one of them had the wire leads stuck into an electrical socket:shock:. One of them works fine but on the other one (which was stuck in the socket) the 123a-1 is blown out and the wiring for the crossover that leads to the midrange doesn't give the midrange any power. The midrange and the tweeter still work (I checked the midrange by putting it in the working one). I also notice that if i wiggle some of the wires in the crossover while the speaker is playing music(with only the tweeter in the cabinet) the tweeter will go on and off. Any suggestions on fixing it? New crossover? HELP! BTW if anyone has a single 123a-1 for sale i might be interested.

Thanks

Sean

[MikeBrewster77]

...the wiring for the crossover that leads to the midrange doesn't give the midrange any power. The midrange and the tweeter still work (I checked the midrange by putting it in the working one)...Any suggestions on fixing it? New crossover?

Process of elimination diagnosis is your best friend here: If the drivers themselves work, then your problem has to be in the crossover provided that the actual wiring (from the XO to each respective driver) is in tact. If you're wiggling wires around and have intermittent power to certain drivers, then you may have some loose wires as well (either in the crossover assembly or from the XO to the drivers.) It could also be a combination of a partially cooked XO and some faulty wiring.

Check all the actual connections at the drivers first, then all of the wiring for continuity. Solder any breaks, and if you still can't get all drivers to operate in that cabinet but they work in another, you'll need to replace the XO.

If you don't mind me asking, how in the hell exactly did a speaker get "plugged into" a wall socket? :dont-know

P.S., There's a pair of XO's on eBay right now with a BIN of $50. No affiliation, and I don't track value to know if that's a deal or not...

http://cgi.ebay.com/JBL-N100-Vintage...3A1%7C294%3A50

[seanbreaux]

Process of elimination diagnosis is your best friend here: If the drivers themselves work, then your problem has to be in the crossover provided that the actual wiring (from the XO to each respective driver) is in tact. If you're wiggling wires around and have intermittent power to certain drivers, then you may have some loose wires as well (either in the crossover assembly or from the XO to the drivers.) It could also be a combination of a partially cooked XO and some faulty wiring.

Check all the actual connections at the drivers first, then all of the wiring for continuity. Solder any breaks, and if you still can't get all drivers to operate in that cabinet but they work in another, you'll need to replace the XO.

Thanks. I know it is the crossover. I just didn't know if it is something to fix or if i have to replace it.

If you don't mind me asking, how in the hell exactly did a speaker get "plugged into" a wall socket? :dont-know

Dont know? Maybe someone was curious

[MikeBrewster77]

Thanks. I know it is the crossover. I just didn't know if it is something to fix or if i have to replace it.

Well, part of it is clearly working since there are drivers that play OK. Can the XO be fixed? Likely, but you'll need test equipment to track down the exact fault, and then the correct parts to fix the anomalies that have been discovered. You put domestic automobile electronics in front of me, and I'm all over that, but when it comes to audio I can replace speaker posts and re-furb a cab (and do a quick and dirty solder job) but after that I'm lost... That's why I would've snagged the XO's that were on eBay, but that's just me...

I'm going out on a limb because I'm the farthest thing from a technical expert here, but I think I remember seeing that member Duaneage could upgrade the L100 network to L100T standard and that it was definitely a worthwhile upgrade. If your network's already cooked, now might be the ideal time to consider an upgrade....

Just a thought

Good luck,
- Mike

[Allanvh5150]

If you don't mind me asking, how in the hell exactly did a speaker get "plugged into" a wall socket? :dont-know

More Power!

Allan.

[Fred Sanford]

I'm going out on a limb because I'm the farthest thing from a technical expert here, but I think I remember seeing that member Duaneage could upgrade the L100 network to L100T standard and that it was definitely a worthwhile upgrade. If your network's already cooked, now might be the ideal time to consider an upgrade....

Just a thought

Good luck,
- Mike

Different animals. The L100 crossover is a pretty simple one with very few parts, the L100T uses entirely different drivers and crossovers.

I'd consider removing and re-building both, either to OEM spec or to one of the upgrades outlined here over the years (I'll see if I can find one of those threads). I'd do both speakers, as the components are now old enough that specs may have drifted & you'd want both to sound alike.

je

[Fred Sanford]

If you don't mind me asking, how in the hell exactly did a speaker get "plugged into" a wall socket? :dont-know

The plan was to connect the other one to a car battery, and listen to some AC/DC.

je

[midlife]

Different animals. The L100 crossover is a pretty simple one with very few parts, the L100T uses entirely different drivers and crossovers.

I'd consider removing and re-building both, either to OEM spec or to one of the upgrades outlined here over the years (I'll see if I can find one of those threads). I'd do both speakers, as the components are now old enough that specs may have drifted & you'd want both to sound alike.

je

If you are putting in the time and energy to get them repaired doing both for consistent results does make sense. I stuck a knife in a toaster when I was a kid...can't remember what happened

[BMWCCA]

I recently was given a pair of L100's, though one of them had the wire leads stuck into an electrical socket:shock:.

I'm almost certain there's some Darwinian principle at work here. I just haven't decided whether the selection process is protecting the world from those who would plug a speaker into a wall outlet, or rather saving future generations from further venerating the L100.

[Loren42]

I recently was given a pair of L100's, though one of them had the wire leads stuck into an electrical socket:shock:. One of them works fine but on the other one (which was stuck in the socket) the 123a-1 is blown out and the wiring for the crossover that leads to the midrange doesn't give the midrange any power. The midrange and the tweeter still work (I checked the midrange by putting it in the working one). I also notice that if i wiggle some of the wires in the crossover while the speaker is playing music(with only the tweeter in the cabinet) the tweeter will go on and off. Any suggestions on fixing it? New crossover? HELP! BTW if anyone has a single 123a-1 for sale i might be interested.

Thanks

Sean

The intermittent sound is due to a bad solder joint. When high current passed through the cross over it melted the solder joints on some of the connections.

First visually inspect the whole board with a magnifying glass. Look for heat damage and melted solder joints. The joints just need to be resoldered.

If the PC board is charred, then the black carbon needs to be scraped away by hand or a dremil tool. Carbon creates a resistive path, so it must be cleaned off.

Inspect components for damage. If coils look melted, then you need to replace them. Resistors tend to burn open. Look for signs of heat damage and replace suspect components.

Caps tend to rupture in small holes.

That will probably catch 75% of any problems. If it still does not work then you need at least a DVM and maybe other equipment, too. However, try what I suggest and see what happens.

[seanbreaux]

The intermittent sound is due to a bad solder joint. When high current passed through the cross over it melted the solder joints on some of the connections.

First visually inspect the whole board with a magnifying glass. Look for heat damage and melted solder joints. The joints just need to be resoldered.

If the PC board is charred, then the black carbon needs to be scraped away by hand or a dremil tool. Carbon creates a resistive path, so it must be cleaned off.

Inspect components for damage. If coils look melted, then you need to replace them. Resistors tend to burn open. Look for signs of heat damage and replace suspect components.

Caps tend to rupture in small holes.

That will probably catch 75% of any problems. If it still does not work then you need at least a DVM and maybe other equipment, too. However, try what I suggest and see what happens.

Today i took out the crossover (It is too bad you have to pull up a corner of the glued on metal sticker with the serial number to get at the 4th screw) and i wiggled the wires and the midrange started to work. I suspect this is temporary. I looked over the crossover and i didnt see any burning. I dont know if the solder melted and messed up the connection or what. I dont really know where to go from here as far as fixing it. If i just want to replace the parts what upgrades should i do? I am very good at fixing things and taking them apart in general but i know nothing about speakers.

[clh1997]

If you consider upgrading the L100 XO, have a look at http://www.troelsgravesen.dk/JBL_L100.htm. It's a vintage speaker website by a Danish guy who seems to know more than the most of us. Rather impresssive I think (no afili).

- Claus

BTW: the AC/DC comment made me laugh loud & long

[Fred Sanford]

BTW: the AC/DC comment made me laugh loud & long

Glad I could help...

je