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Author Topic: Crossover replacement part Deux  (Read 1004 times)

Jason L Holland

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Crossover replacement part Deux
« on: March 14, 2022, 07:24:09 PM »

Wonder if you folks can help. I got a donated Portable PA system (Behringer Eurolive EPA900) that I want to re-donate to my kids elementary school. Problem is one of the speakers has a tweeter out. Looks like it's in the crossover. Here's what I've done.

Tried known good tweeter in the speaker - no joy - Test voltage coming to HF leads - zero voltage) - Reflowed all the solder joints on the crossover and inspected for obvious damage - no joy -

The LF speaker works fine so it seems like it's something in the HF part of the crossover.

Behringer doesn't sell a replacement crossover and only recommend replacing the entire speaker.

Thoughts on what I should do next? I was thinking maybe getting a 2 way crossover from amazon or ebay and just trying it to see. I guess I could test each componet and replace but not sure if it's the pcb board so...

How do I choose a comparable crossover to what I have? The speaker is a 10" LF woofer and 1.35'' aluminum-diaphragm compression drivers. The amp is 450watts per side.

so Would I be good to try something like:

https://www.amazon.com/Durability-Crossover-Frequency-12-18inch-Professional/dp/B08D3SVVXM/ref=sr_1_4?crid=20S1O6P8AF36K&keywords=2+way+crossover+500+watt&qid=1647116375&sprefix=2+way+crossover+500+watt%2Caps%2C42&sr=8-4

It just needs to be 500 watts or so? Should I worry where the crossover point is? It's just gonna be used for music and speaking mostly.

Thanks for any help!
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Paul G. OBrien

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Re: Crossover replacement part Deux
« Reply #1 on: March 14, 2022, 07:59:15 PM »

Post up some pics of the crossover, it's probably an open capacitor or resistor.
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Jason L Holland

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Re: Crossover replacement part Deux
« Reply #2 on: March 15, 2022, 09:13:44 PM »

Post up some pics of the crossover, it's probably an open capacitor or resistor.

Thanks for the reply. Here are some pics...

https://imgur.com/a/GsheQFV
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Brian Jojade

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Re: Crossover replacement part Deux
« Reply #3 on: March 15, 2022, 09:39:02 PM »

You've got 2 speakers, one working and one not.

First step, swap crossovers to confirm that's the issue.

Second step, start measuring values between the crossovers to see what components don't match.  There aren't a lot, so you could even go as far as swapping components on the crossovers to see where the problem is.
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Brian Jojade

Jason L Holland

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Re: Crossover replacement part Deux
« Reply #4 on: March 15, 2022, 09:46:16 PM »

You've got 2 speakers, one working and one not.

First step, swap crossovers to confirm that's the issue.

Second step, start measuring values between the crossovers to see what components don't match.  There aren't a lot, so you could even go as far as swapping components on the crossovers to see where the problem is.

Great advice. Anyone know of a guide to testing components? I have a good multimeter but not great knowledge. :)

I assume if I find the bad component then I could get it at digikey or somewhere like that?

Thanks again for your replies

J
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Art Welter

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Re: Crossover replacement part Deux
« Reply #5 on: March 16, 2022, 01:36:24 PM »

Great advice. Anyone know of a guide to testing components? I have a good multimeter but not great knowledge. :)

I assume if I find the bad component then I could get it at digikey or somewhere like that?

Thanks again for your replies

J
The PCB should be simple point to point resistance, near "0" ohms.
The coils should read a low resistance, probably under 1 ohm. If they don't look burnt, the value in MH is of no concern to you. If you need to replace one (one is in parallel with the HF (tweeter), one in series with the LF (woofer) you will need to measure the working unit with an LCR meter, or find the value from a schematic.
The 25W (watt) and 10W resistors should read within J=+/-5% of their nameplate resistance "R", 2.7 ohms (2R7) or 4ohms. One is in series with the HF, one in parallel.
If the series resistor is open, the HF will be dead.
One capacitor is probably in parallel with the woofer.
The other two capacitors pass signal to the HF.
Capacitor testing:
https://www.electronicshub.org/how-to-test-a-capacitor/?msclkid=1b991b4ba54a11eca61267ee33686e85

With some clip leads, a signal source, and a speaker, you could "jump" over any component and find which does not work, narrowing down the search, as Paul mentioned, likely an open capacitor or resistor.

Art
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Jason L Holland

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Re: Crossover replacement part Deux
« Reply #6 on: April 16, 2022, 04:39:45 PM »

Thanks for the reply. I'm finally able to dig into this.

I did switch the crossover from the known good speaker to the non working speaker and confirmed that the problem is in the bad speaker's crossover.

Do the components I'm testing need to be desoldered from the pcb to test? I imagine so?

Thx!






The PCB should be simple point to point resistance, near "0" ohms.
The coils should read a low resistance, probably under 1 ohm. If they don't look burnt, the value in MH is of no concern to you. If you need to replace one (one is in parallel with the HF (tweeter), one in series with the LF (woofer) you will need to measure the working unit with an LCR meter, or find the value from a schematic.
The 25W (watt) and 10W resistors should read within J=+/-5% of their nameplate resistance "R", 2.7 ohms (2R7) or 4ohms. One is in series with the HF, one in parallel.
If the series resistor is open, the HF will be dead.
One capacitor is probably in parallel with the woofer.
The other two capacitors pass signal to the HF.
Capacitor testing:
https://www.electronicshub.org/how-to-test-a-capacitor/?msclkid=1b991b4ba54a11eca61267ee33686e85

With some clip leads, a signal source, and a speaker, you could "jump" over any component and find which does not work, narrowing down the search, as Paul mentioned, likely an open capacitor or resistor.

Art
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Steve-White

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Re: Crossover replacement part Deux
« Reply #7 on: April 16, 2022, 05:31:15 PM »

Great advice. Anyone know of a guide to testing components? I have a good multimeter but not great knowledge. :)

I assume if I find the bad component then I could get it at digikey or somewhere like that?

Thanks again for your replies

J

You could also find an electronics technician in the area and let them do it.  A crossover will require non-polarized electrolytic capacitors which are a specialty item.
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Paul G. OBrien

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Re: Crossover replacement part Deux
« Reply #8 on: April 16, 2022, 07:19:43 PM »

Do the components I'm testing need to be desoldered from the pcb to test? I imagine so?

Lifting one side of the component from the circuit board is usually sufficient. The 3 components on the lower left side of the board in your pics appear to be for the HF driver, that is the white 10W2R7J resistor, the immediately adjacent yellow capacitor, and the smaller of the two inductors. I'd start by just heating and reflowing all the solder joints on the components as a cold(cracked) solder joint is a common problem. If that doesn't fix it start with the resistor and lift one side out of the PCB, these are prone to cracking internally and becoming open circuit. A quick test with the multimenter on the ohms setting should tell you if it's good or not, it should measure about 2.7 ohms. The capacitor will measure open circuit on the multimeter, it's unlikey it is bad unless it's physically burnt so you may have to change it to know for sure. The coil should meansure as a dead short, if you don't get that it's bad but this would be the most unlikely failure.
« Last Edit: April 16, 2022, 07:26:31 PM by Paul G. OBrien »
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Jason L Holland

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Re: Crossover replacement part Deux
« Reply #9 on: April 17, 2022, 08:28:37 PM »

Thanks all. I've already reflowed the solder joints so I don't think that was it.

So I'll start with the small resister then move on to the other HF components. Quick questions...

So by what you're saying the cap isn't measurable it will just show open? Maybe just replace it? Digikey?

I get a dead short on the coil but how would that show on my multimeter? Open and zero resistance?

Thanks again! If I can't find the issue with these quick tests I'll take it to a electronics guy. Anyone know a good place in Atlanta?

J


Lifting one side of the component from the circuit board is usually sufficient. The 3 components on the lower left side of the board in your pics appear to be for the HF driver, that is the white 10W2R7J resistor, the immediately adjacent yellow capacitor, and the smaller of the two inductors. I'd start by just heating and reflowing all the solder joints on the components as a cold(cracked) solder joint is a common problem. If that doesn't fix it start with the resistor and lift one side out of the PCB, these are prone to cracking internally and becoming open circuit. A quick test with the multimenter on the ohms setting should tell you if it's good or not, it should measure about 2.7 ohms. The capacitor will measure open circuit on the multimeter, it's unlikey it is bad unless it's physically burnt so you may have to change it to know for sure. The coil should meansure as a dead short, if you don't get that it's bad but this would be the most unlikely failure.
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Paul G. OBrien

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Re: Crossover replacement part Deux
« Reply #10 on: April 17, 2022, 09:34:00 PM »

So by what you're saying the cap isn't measurable it will just show open? Maybe just replace it? Digikey?

I get a dead short on the coil but how would that show on my multimeter? Open and zero resistance?

A dead short on a multimeter equals zero resistance... same as when you touch the two leads to one another.
An open circuit is what is displayed when the leads aren't touching anything.

I looked at your pixtures again and I believe both resistors are in the circuit for the tweeter, this makes sense as it usually needs attenuation to match levels with the woofer so you need to test both. These are the most likely cause of your problem although it could be the capacitor as well. If the resistors test good try swapping in the capacitor from the other crossover. If that is the problem they are available from many online places so won't be hard to find.
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Steve-White

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Re: Crossover replacement part Deux
« Reply #11 on: April 17, 2022, 09:39:19 PM »

The coils (Chokes) on the crossover will show "0" resistance when measured with a standard hand held DVM.
« Last Edit: April 18, 2022, 09:34:23 AM by Steve-White »
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Scott Holtzman

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Re: Crossover replacement part Deux
« Reply #12 on: April 17, 2022, 11:36:04 PM »

The coils (Chokes) on the crossover will show "0" resistance in a standard hand held DVM.


Please note the electrons may be a bit busy after all those trips around the phase wheel.  Eli The Iceman, still my favorite pneumonic. 

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Scott AKA "Skyking" Holtzman

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Brian Jojade

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Re: Crossover replacement part Deux
« Reply #13 on: April 18, 2022, 12:51:50 AM »

Thanks all. I've already reflowed the solder joints so I don't think that was it.

So I'll start with the small resister then move on to the other HF components. Quick questions...

So by what you're saying the cap isn't measurable it will just show open? Maybe just replace it? Digikey?

I get a dead short on the coil but how would that show on my multimeter? Open and zero resistance?

Thanks again! If I can't find the issue with these quick tests I'll take it to a electronics guy. Anyone know a good place in Atlanta?

J

You can't measure a capacitor with a standard multimeter. There are some meters that can measure capacitors to see that they are working at the right values.

Since you're dealing with just a few components here, it's easy enough to swap them between the working unit and the non working unit.  If you can't isolate to a component, then it's possible that a trace has cracked on the bad unit.

The coil when read with a multimeter will read as a dead short, close to 0 ohms resistance.  If it reads open, it's bad.  It's very unlikely that the coil has gone bad.
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Brian Jojade

ProSoundWeb Community

Re: Crossover replacement part Deux
« Reply #13 on: April 18, 2022, 12:51:50 AM »


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