I've owned a pair of Optimus LX10 loudspeakers for about ten years now. About five years ago I noticed that the dipole ribbon tweeters on both speakers weren't producing any sound. The woofers were making noise just fine, just not the tweeters.
Fast forward to a couple weeks ago when I decided to try and fix them. I did some research on the interwebs and found a post on audioreview about a fuse on the circuit board inside the speaker that had a tendancy to blow.
I cracked one of the speakers open to check said fuse only to find that it is intact! Ok, lets check for leaky caps... nothing - it all looks good. What could be the problem here?
Do these tweeters go bad? I don't really understand how; I mean, they are a ribbon, magnets, and wiring - what component could fail?
Here is a picture of the circuit board. I have a digital multimeter, how can I test this circuit to check which component (if any) is defective?
Fast forward to a couple weeks ago when I decided to try and fix them. I did some research on the interwebs and found a post on audioreview about a fuse on the circuit board inside the speaker that had a tendancy to blow.
I cracked one of the speakers open to check said fuse only to find that it is intact! Ok, lets check for leaky caps... nothing - it all looks good. What could be the problem here?
Do these tweeters go bad? I don't really understand how; I mean, they are a ribbon, magnets, and wiring - what component could fail?
Here is a picture of the circuit board. I have a digital multimeter, how can I test this circuit to check which component (if any) is defective?
Attachments
those dipole tweeters have actualy voice coils, except they are arranged in line, etched from copper foil
check those with ohm meter
check those with ohm meter
measurement results
I placed the multimeter's probes on the spade connectors for the dipole tweeter. I set the digital multimeter selector to the 20M OHM range and got .2 on the readout.
I'm guessing this means that the tweeter is shot as I should get a reading of 6 with the selector set to 200 OHM right?
Thanks for your help so far.
I placed the multimeter's probes on the spade connectors for the dipole tweeter. I set the digital multimeter selector to the 20M OHM range and got .2 on the readout.
I'm guessing this means that the tweeter is shot as I should get a reading of 6 with the selector set to 200 OHM right?
Thanks for your help so far.
dismantlement
I'm assuming I am correct in that the dipole tweeter is busted. Has anyone ever taken one of these things apart?
I don't see any screws anywhere, it actually looks like it was glues together; but I've been wrong about simpler things before 😱
Thanks,
Serge.
I'm assuming I am correct in that the dipole tweeter is busted. Has anyone ever taken one of these things apart?
I don't see any screws anywhere, it actually looks like it was glues together; but I've been wrong about simpler things before 😱
Thanks,
Serge.
Hi masofshad,
yes, at range 200 ohms the tweeter should measure close to 6 ohms. If it reads 0.2 ohms, than its shorted. If it reads 0.2 Mohms, than its open/burned. In any case its not a good sign.
I took some of those apart, but was not able to put them back!
Yes, they are glued together. Time to get new tweeters.
How about this one:
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=297-409
It's nice sit on top of the cabinet.
yes, at range 200 ohms the tweeter should measure close to 6 ohms. If it reads 0.2 ohms, than its shorted. If it reads 0.2 Mohms, than its open/burned. In any case its not a good sign.
I took some of those apart, but was not able to put them back!
Yes, they are glued together. Time to get new tweeters.
How about this one:
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=297-409
It's nice sit on top of the cabinet.
Hi,
It is very unusual for a tweeter to fail by going short,
it is nearly always a terminal open circuit failure.
🙂/sreten.
It is very unusual for a tweeter to fail by going short,
it is nearly always a terminal open circuit failure.
🙂/sreten.
adason said:If it reads 0.2 Mohms, than its open/burned.
Yup, it's 0.2 Mohms!
sreten said:Hi,
It is very unusual for a tweeter to fail by going short,
it is nearly always a terminal open circuit failure.
🙂/sreten.
Indeed, it's open.
I think I'm going to take a stab and cutting it open with my deremel!!
WOOHOOO!!!
Thanks,
Serge.
adason said:How about this one:
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=297-409
It's nice sit on top of the cabinet.
Thanks for the suggestion - the website is a great source for speakers!
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