Repairing JBL Eon 618s subwoofer - schematic needed (or two component values)

[cozza]

Repairing a group of JBL Eon speakers from an installation in a gym, all three units failed after a power outage. The speakers have been powered on continuously for three and a half years, playing low level background music - an easy life for a PA speaker - you might think. No touring, no band / DJ thrashing.

The full range cabinets needed a full power supply / amp board recap (most of the electrolytic caps had dried out, bulged and a couple had blown the tops off) - Both of these now repaired. Scan with a thermal camera showed the reason for the cap failure - the output filter chokes run at 70 ish degrees at idle, and the caps are all mechanically and thermally bonded to one another and the hot inductors with silicone.

The sub had had a flash over in one area, under some type of other adhesive  - I've seen another picture online of this module and it is black in colour normally. Black and crispy with a clear liquid residue around the edges in this case.

Under the glue on one side are the resistor divider chains for the SMPS control IC, for HV bus sense from the bulk filter caps.

Also a sense network from the incoming mains phase, which is a power fail fast shut down for the power supply (Class D amplifiers can go unstable as the supplies go down) comprised of a RS1K diode, 3 x 470K resistors in series and a few other components. (Note - this network turned out to be the startup supply for the L6599AD on closer inspection)

Under the microscope I could see C74 had cracked and emitted smoke (shorted) - a noise suppression cap on pin 7 of the L6599AD to ground.

-  Line sensing input. The pin is to be connected to the high-voltage input bus
   with a resistor divider to perform either AC or DC (in systems with PFC)
   brownout protection. A voltage below 1.24 V shuts down (not latched) the
   IC, lowers its consumption and discharges the soft-start capacitor. IC
   operation is re-enabled (soft-started) as the voltage exceeds 1.24 V. The
   comparator is provided with current hysteresis: an internal 13 μA current
   generator is ON as long as the voltage applied at the pin is below 1.24 V
   and is OFF if this value is exceeded. Bypass the pin with a capacitor to
   GND to reduce noise pick-up. The voltage on the pin is top-limited by an
   internal Zener. Activating the Zener causes the IC to shut down (not
   latched). Bias the pin between 1.24 and 6 V if the function is not used.

Looking at the the clear liquid residue around the failure point, I initially thought that it was electrolyte from the 4 bulk filter caps which are next to it, but removal and inspection of the caps showed no sign of leakage - actually they were the few electrolytics in this speaker set which still met spec for ESR and capacitance. Replaced them regardless with some 10,000 hour Nichicons for future reliability. The liquid appears to be from heat decomposition of the black adhesive - a process which made it conductive in a particularly bad place to have conductive residue.

The two switching Mosfets test OK out of circuit - I replaced the L6599A as it would likely be damaged from the flash over to its sense inputs.

The RS1K diode D20 in the mains sense network was shorted, also C74 on the line input to the IC, and diode D25 also shorted - a MELF package with a green stripe, I believe to be a zener diode. A couple of blown thin tracks have been repaired. The resistors in the divider chains have all been replaced as they were looking a bit charred.
Theoretically when I replace C74 (MLCC, value and voltage unknown) and diode D25 (glass, melf, green stripe, presumably zener diode, voltage unknown) it should be back in working order. All other passives were tested in circuit while the L6599 was removed.

I will replace the main switching mosfets as well (TSC 60NB190) in case they were stressed by the failure. Have them on order from Digikey.

I haven't had any luck finding a schematic for this amp module online (a lot of earlier EON schematics, but completely different power supplies)

Hopefully someone out there can assist with these component values. I'll draw out the line sense network when I get a chance if anyone is interested.

Conclusion -  JBL Eon 612 / 618S product is not suited to be powered on 24/7 in an installation situation.

[cozza]

Here's a couple of close ups of the area

[EHT]

Conclusion -  JBL Eon 612 / 618S product is not suited to be powered on 24/7 in an installation situation.

Probably no Class-D amp is? In particular those with the amp built into the speaker enclosure with no ventilation. I think you can get some where the amp is built-in but not part of the speaker enclosure and thus vented or with a decent heatsink.

[cozza]

I feel I should contact the AV company who provided this solution and let them know it's not fit for this type of purpose. Fortunately the rest of the installation is done with rack mounted amplifiers and an passive cabinets, which have been fine.

Also I forgot to mention some back story, the first full range cabinet failed at the two year mark just out of warranty - two 470uF 25V caps in the power supply for the DSP signal processing circuitry are the first point of failure in these - symptom was oscillation around 2kHz, like the worlds most unpleasant (and probably loudest) alarm siren.

These are the two caps which the tops blow off. At the time it got repaired, only those two caps had failed, so replacing them fixed the speaker. The other caps tested OK for ESR and capacitance at that time.

I've been expecting a follow up on this repair for a while now for the second full range cabinet, but I didn't expect both the full range cabinets and the sub to fail simultaneously.

This time the sub cabinet was tripping the RCBO supplying it - not surprising as the back panel is earthed.



I've had a chance to probe around the circuit some more, and have discovered that the line sense input to the IC (pin 7) is coming from positive of the main filter caps, via the resistor string which flashed over.

The other mains referenced part of the circuit (RS1K diode + 3 x 47k series resistors and zener diode + sot23 transistor is the startup supply for the L6599AD, and I have some idea of the zener voltage from the two application notes from ST - around 15.5V which would make sense. It's not exactly the same, but close enough to get the idea.

The shorted ceramic cap between pin 7 of the L6599AD and ground is a noise smoothing cap for that input. It saw excessive voltage when the resistor divider flashed over, under the black goop.

A value between 1 and 10nF is recommended here in the datasheet, with 4n7 used in the application note.

[cozza]

These have the amplifier built into a separate pocket with ventilation.. But yes you're right.

I'm going to put this group of speakers on a time schedule using shelly switches, so they're only active during staffed hours, and not 24/7 - this will improve the lifespan.

[cozza]

Found this on the JBL website.

Technically yes, installable. But not suitable for continuous operation.

[DavidAlfa]

Here's the eon615, it might shed some light.

Edit: D25 seems to be a 13V zener, like D14

[cozza]

Thank you, that's great. I'd figured out the 13V zener voltage and the capacitance (2.2uF) for the line sense input cap looking at the amp module for the 612 full range cabinet, but it's nice to confirm cap voltage before placing the order

[Gae]

Hi.

So Cozza, did you repaired them ?

I am repairing also a Eon 612, sometimes it starts ok, sometimes it does not light on ...
Sometimes after 10 minutes it just shut off alone.
Other times, after 2 hours, it still work fine...

I suspect it could be the oscillator L6599, does that make sense ? I updated the firmware and reseted it, same problem...
I haven't open it yet but as you already repaired some of those I'd be very glad to have a return from you.

Cozza, are you italian ? I'v lived in Firenze for 6 years !

[Jeff eelcr]

It looks like a lighting strike or HV input of some type.
Jeff

[Norbert67]

They dont need any of that.
I saw one of these, out of nowhere, half of the PSU board burned down.
Shitty design
Repaired a 518s once (never again!)
Small heatsink for a 500W amp, closed enclosure, passive cooling, and the speaker is a joke - I never saw anything like it .
For those who remember the products JBL created in the 70s and 80s this is an embarrassment.
I needed to put there mached new MosFETs - for the PSU and the amp, new IR2111s , couple of fuses and diodes.
But getting out the digital amp PCB and getting rid of those glues are another story.
I wish You luck with the repairing!

[Gae]

Many thanks.

I just opened it and found out the NTC filter is making a bad connection, in fact one to the "leg" was almost cutted and it affected the 33k resistor next to it. NT1 and R78
I'll get one of each new and solder them, it should fix the problem.
In reality I am repairing a Eon 612 ...

Norbert67 it seem you don't like it, no ?
What I found out, after repairing some of those type of amps, that the class"D" amps often are built (China?) "as cheep as possible" and - is it a idea of mine or is it the reality ? - they are very fragile ! Any small problem affects often the rest of components and make them very hard (and complicate) to repair. 

500W in a so light case  how is it possible ?

[3roomlab]

500W in a so light case  how is it possible ?

I think - 1000W @ 10% distortion endurance 10 minutes? Maybe 100W/1% for long term? But im not sure, usually there is a rating specification to tell the user the watts = ?? THD. So you get some idea what not to do and derate the system etc according to the application.

[cozza]

HI I've had a few PM's regarding repairing these units, I'm not interesting in taking on any more of them, thanks.

I was under spousal obligation to remedy the others which overides my unwillingness to work on badly designed products 

[krisskross]

Repairing a group of JBL Eon speakers from an installation in a gym, all three units failed after a power outage. The speakers have been powered on continuously for three and a half years, playing low level background music - an easy life for a PA speaker - you might think. No touring, no band / DJ thrashing.

The full range cabinets needed a full power supply / amp board recap (most of the electrolytic caps had dried out, bulged and a couple had blown the tops off) - Both of these now repaired. Scan with a thermal camera showed the reason for the cap failure - the output filter chokes run at 70 ish degrees at idle, and the caps are all mechanically and thermally bonded to one another and the hot inductors with silicone.

The sub had had a flash over in one area, under some type of other adhesive  - I've seen another picture online of this module and it is black in colour normally. Black and crispy with a clear liquid residue around the edges in this case.

Under the glue on one side are the resistor divider chains for the SMPS control IC, for HV bus sense from the bulk filter caps.

Also a sense network from the incoming mains phase, which is a power fail fast shut down for the power supply (Class D amplifiers can go unstable as the supplies go down) comprised of a RS1K diode, 3 x 470K resistors in series and a few other components. (Note - this network turned out to be the startup supply for the L6599AD on closer inspection)

Under the microscope I could see C74 had cracked and emitted smoke (shorted) - a noise suppression cap on pin 7 of the L6599AD to ground.

-  Line sensing input. The pin is to be connected to the high-voltage input bus
   with a resistor divider to perform either AC or DC (in systems with PFC)
   brownout protection. A voltage below 1.24 V shuts down (not latched) the
   IC, lowers its consumption and discharges the soft-start capacitor. IC
   operation is re-enabled (soft-started) as the voltage exceeds 1.24 V. The
   comparator is provided with current hysteresis: an internal 13 μA current
   generator is ON as long as the voltage applied at the pin is below 1.24 V
   and is OFF if this value is exceeded. Bypass the pin with a capacitor to
   GND to reduce noise pick-up. The voltage on the pin is top-limited by an
   internal Zener. Activating the Zener causes the IC to shut down (not
   latched). Bias the pin between 1.24 and 6 V if the function is not used.

Looking at the the clear liquid residue around the failure point, I initially thought that it was electrolyte from the 4 bulk filter caps which are next to it, but removal and inspection of the caps showed no sign of leakage - actually they were the few electrolytics in this speaker set which still met spec for ESR and capacitance. Replaced them regardless with some 10,000 hour Nichicons for future reliability. The liquid appears to be from heat decomposition of the black adhesive - a process which made it conductive in a particularly bad place to have conductive residue.

The two switching Mosfets test OK out of circuit - I replaced the L6599A as it would likely be damaged from the flash over to its sense inputs.

The RS1K diode D20 in the mains sense network was shorted, also C74 on the line input to the IC, and diode D25 also shorted - a MELF package with a green stripe, I believe to be a zener diode. A couple of blown thin tracks have been repaired. The resistors in the divider chains have all been replaced as they were looking a bit charred.
Theoretically when I replace C74 (MLCC, value and voltage unknown) and diode D25 (glass, melf, green stripe, presumably zener diode, voltage unknown) it should be back in working order. All other passives were tested in circuit while the L6599 was removed.

I will replace the main switching mosfets as well (TSC 60NB190) in case they were stressed by the failure. Have them on order from Digikey.

I haven't had any luck finding a schematic for this amp module online (a lot of earlier EON schematics, but completely different power supplies)

Hopefully someone out there can assist with these component values. I'll draw out the line sense network when I get a chance if anyone is interested.

Conclusion -  JBL Eon 612 / 618S product is not suited to be powered on 24/7 in an installation situation.

I know this may be a old topic, but im having same issue as TS. Id just like to find out the value of C47. Is it 2.2uf or 220nf? Thanks TS and once again apologies for bumping a old thread. Currently ive replaced the diode, the fuse, the capacitor to 220nf. The unit works fine, but just afraid for long term it may blow again. If 220nf for c47 is fine, then ill just let it be.

[cozza]

If its the cap from pin 7 of the L6599A to ground you mean, its 2.2uF 6.3V

[krisskross]

If its the cap from pin 7 of the L6599A to ground you mean, its 2.2uF 6.3V

this ceramic cap c74

[krisskross]

If its the cap from pin 7 of the L6599A to ground you mean, its 2.2uF 6.3V

hope you remember the  value