JBL EON 618S Heat troubleshooting

[sorel]

Hi everyone.

With a standard ambient temperature (let's say 25°C) sound disappears then comes back and so on.

Since the "cut" is neat i guess this is a controled shudown operated by the controler (IRS2052M) of the full bridge class D amplifier due to overtemperature detection.(OVT)
Comparing jbl implementation of OVT and controler datasheet it seems there something weird about jbl design.

Has anyone already worked on this specific device ? I'm looking for advices

Thanks for reading

Pierre

[Jazz P Bass]

Do you have a schematic that you can post?

Are pins 2,3,29 being used on the board?

[sorel]

Hi Jazz P Bass.
i would love to have the schematic/service manual but ...no
pins 2 & 3 are not used (only connected to test points on the pcb
there's a ptc (the one recommended in IRS2052M data sheet) with a sensing temperature around 100°C according to my measurements in mosFet neighborhood on the power pcb connected to pin 29 but what i don't understand is that JBLput a 2,6 k resistor in serie ; therefore sensing temperature is shifted much lower (and the warning temperature is reached from start)

[g1]

there's a ptc (the one recommended in IRS2052M data sheet)
...
but what i don't understand is that JBLput a 2,6 k resistor in serie ; therefore sensing temperature is shifted much lower (and the warning temperature is reached from start)

I couldn't find the PTC recommendation, datasheet attached. Where do you see it?
Pin29 voltage should be checked with reference to pin30 (COM). Have you done pin29 voltage checks ? Maybe shut-down is caused by something else?

[x-pro]

How fast is the first disconnection-time interval? Power level before the signal goes out, time interval between signal disappearance and resumption?
What are the power supply voltages at the power supply output during normal operation and when the defect occurs?

[The Dude]

FWIW: Check drivers first. I had one recently doing the same thing. The LF driver measured .7Ω (shorted voice coil). Surprisingly, the unit still worked until you drove it a bit harder. I was surprised it didn't blow up the amp, but it didn't.

[x-pro]

https://help.harmanpro.com
Type EON618S in the search bar.
Information about RESET will appear.
Give it a try.

[sorel]

How fast is the first disconnection-time interval? Power level before the signal goes out, time interval between signal disappearance and resumption?
What are the power supply voltages at the power supply output during normal operation and when the defect occurs?

I don't have these specific information since i could'nt reproduce the malfunction in my workshop (maybe a too low ambiant temperature (around 14°C)
i've only got the user account (and a little video he made on the occasion) : while the subwoofer was working (for the first time since he bought it) outside on a not so warm summer afternoon (around 28°C) sound suddenly disappear for few seconds then comes back and so on ; I can clearly see in the video that the LED input signal is still blinking while sound is off meaning that power rails are still ok (at least some of them).
Besides there's almost no chance that a neat sound cut can be caused by a power rails failure without issuing on the falling or rising edge some weird cracks or noised of anykind
That's why i suspect a conroled shutdows from the power FETs controler

[sorel]

FWIW: Check drivers first. I had one recently doing the same thing. The LF driver measured .7Ω (shorted voice coil). Surprisingly, the unit still worked until you drove it a bit harder. I was surprised it didn't blow up the amp, but it didn't.

Loudspeaker as been checked ; 3,5 ohm seems ok for a 8 ohm impedance ; but thanks for the tip

[sorel]

https://help.harmanpro.com
Type EON618S in the search bar.
Information about RESET will appear.
Give it a try.

thanks for the link ; i could be useful after replacing the IRS controler (and maybe the 4 FETs)

[sorel]

I couldn't find the PTC recommendation, datasheet attached. Where do you see it?
Pin29 voltage should be checked with reference to pin30 (COM). Have you done pin29 voltage checks ? Maybe shut-down is caused by something else?

i got this information from another more detailed document about the IRS controler.
controled shudown si due to 3 different causes :

over temperature of IC itself or external monitored spot near the 4 power FETs
over current in the FETs
external command (via VSD pin)

Loudspeaker is ok so i rejected overcurrent issue
without schematic i don't have a clear view on the external command (VSD) circuitry but yes i could be the cause

I suspect heating problems because first it's a common issue but mostly because the plastic box on which the rear panel is attached as been opened in order i guess to get some more air flow coming from inside the subwoofer case ; this has been done by the previous owner : it didn't solved the problem and that's why i guess he sold it to the actual owner.

[x-pro]

Check the quality of soldering of the output chokes. They're so big. Ferrite square. There should be two of them there. Sometimes a similar malfunction occurs in the breakage of the inductor output at the soldering site due to vibrations. It is enough to warm up the inductor terminal with a soldering iron and pull it with tweezers.