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How do you know if your Jbl SRX718s is dead?


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It's the last piece of gear that I would think would crap out on me.  I barely play this thing like brand freakin new.  I tried different speakon cables and nothing..no signal on the amp.  Amp is working for sure..tested it with different speaker.  Is there a fuse or something inside the sub?

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A 9v battery across the leads of the speaker can quickly tell you if its working.

 

Also verify that the sub s accepting signal on pins1 and not pins 2, its either a physical switch on the back near the input or you'd have to remove the input plate.

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I'll open the grille tomorrow and inspect. I've got the sub on +1/-1 setting and the speakons are the cheap kind. Not sure how they are configured. On the qsc amp I tried both the full range and high pass switch...seems to have green led signal blinking but not noise or vibration out of the sub. I tried plugging in both top and bottom speakon "outlet" on the sub. I'm not sure what the difference in using the top or bottom plug to be honest.

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lilgrasshopper wrote:

I'll open the grille tomorrow and inspect. I've got the sub on +1/-1 setting and the speakons are the cheap kind. Not sure how they are configured. On the qsc amp I tried both the full range and high pass switch...seems to have green led signal blinking but not noise or vibration out of the sub. I tried plugging in both top and bottom speakon "outlet" on the sub. I'm not sure what the difference in using the top or bottom plug to be honest.

 

You haven't mentioned whether you had the same configuration of amp, cables, and speaker working properly originally. Please confirm.

On the SR-X (the prior series), the input jackplate is removable, and the switching network circuit board is attached to the speakers with wiring connectors. I've had these loosen. See if this may be the case for your speaker as well. I had to simply snap the connector in and everything worked fine.

Failing this, the 9v battery test mentioned earlier should confirm whether the speaker driver itself is working.

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Speakons are fine. After the battery test,I concluded that the speaker is fine. Either the board is bad or the neutriks are "loose". In either case, I just ordered a replacement input board....that should work. I'll post my result after I get it wednesday or so.

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amp is configured *1/-1; the speakons have 2 wires inside so I'm sure it's also +1/-1.  I never messed with it so I can't imagine it's configured anything different.  I've got 2 speakon wires...so there's no way 2 could fail in a row.  Can't wait to find out but I'm relieved my sub isn't blown.

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Did you confirm with the battery test at the source end of the speaker cable?

 

Did you confirm that you had signal at the 1+/- output terminals of the amp?

 

I have a strong feeling that you are barking up the wild ass guess tree with incomplete or inaccurate troubleshooting.

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If the amp is mistakenly wired to provide +2 -2 instead, all he'd have to do was throw the switch and he'd get output. I suspect the NL4 wiring.

Its unlikely the board is fried. Here is a photo of the inside of a 718. Notice the location of the connector on the board, its in the lower position. This is the same board that is used for the SRX728.

 photo.JPG

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OK, so I got the replacement backplate...popped it in...still nothing happened...then luckily I have an extra speakon that I've never ever used...viola!  It worked...so moral of the story is check your wires thrice if u need to!  Everything works now even the oem backplate. Silly me ;))  Thanks guys! Always there to comfirm DA's like myself.

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lilgrasshopper wrote:

Speakon cable came like that. Only one side is like that. Not sure why.

 

Do you have the packaging it came in, or if you purchased online, have a link to where you got it? I'm very curious about how it was described. Does it have a shrinkwrap sleeve on that end that describes the schematic? Some cables have "1+, 1-" or similar to denote which terminals are used.

It's not too unusual to have a custom cable that may run from the 1+- pair to the 2+- pair, for instance, in order to mate a given amp output to a given speaker input. Such cables would need to be marked at each end to minimize (note I didn't write "avoid") confusion.

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