EEVblog 1672 - JBL REPAIR: You'll never guess the fault - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: March 04, 2025, 11:11:46 pm
content: Repair of a JBL Partybox 310 speaker. Follow along as Dave goes down the repair rabbit hole. Try and guess the exact fault before Dave does, it's a doozy!00:00 - JBL Partybox 310 Speaker fault symptoms and initial failure speculation02:57 - Teardown06:23 - Is it a firmware lockup issue?07:17 - Checking the power switch09:13 - Main PCB's10:52 - Hello IT, have you tried turning it off and on again11:46 - PCB microscope inspection13:39 - Bench testing and, thou shalt test voltages16:31 - Looking at the keypad PCB again17:41 - Replicate the fault using an external PSU22:55 - Schematic, we have Schematic!24:14 - The power flow block diagram28:44 - The penny drops29:45 - Design TIP32:04 - Without the schematic I'd be chasing a red herring down a rabbit hole33:10 - Manual Bypass time to get it working!34:50 - I called it at the start, but assumed incorrectly36:33 - OK, let's trace WHERE this fault actually is37:41 - No, it's can't be, surely not...39:52 - But WHAT caused it?42:05 - The repair44:20 - Assembly back together and testingPart 2:

author: MLXXXp
author_rank: Frequent Contributor
timestamp: March 05, 2025, 02:40:08 am
content: @EEVblog, I hope for thoroughness you replaced the ECHO - button that had the bad "clicker", while you had access to it. Yes, I know it probably still worked fine but, at least for me, my OCD would have forced me to change it.

author: EEVblog
author_rank: Unknown
timestamp: March 05, 2025, 04:08:32 am
content: Quote from: MLXXXp on March 05, 2025, 02:40:08 amIn all the excitement, I forgot!

author: Kleinstein
author_rank: Super Contributor
timestamp: March 05, 2025, 08:29:40 am
content: The design of the 2 PCBs for the buttons is really odd: not just the rediculous number of zero ohm links, but also having 2 PCBs side by side with the extra cable.

author: kleiner Rainer
author_rank: Regular Contributor
timestamp: March 05, 2025, 09:07:12 am
content: My opinion: the power button is the only button that has a voltage across it all the time - even when the speaker is off, so any corrosive liquid has all the time it needs to corrode the copper trace. The other traces nearby are not corroded because there is no voltage on them when off.Even rain water is conductive enough to destroy circuit boards given enough time - I found that out when a phantom power unit for a Sennheiser artificial head microphone got rain soaked - a few hours with 9V dissolved a trace on the pcb!Greetings,Rainer DG1SMD

author: EEVblog
author_rank: Unknown
timestamp: March 05, 2025, 09:49:06 am
content: Quote from: Kleinstein on March 05, 2025, 08:29:40 amYes, odd, unless theree another model without half the controls. But even then you just don't populate them.

author: EEVblog
author_rank: Unknown
timestamp: March 05, 2025, 09:49:31 am
content: Quote from: kleiner Rainer on March 05, 2025, 09:07:12 amYes, that's what my Part 2 video is about.

author: Langdon
author_rank: Frequent Contributor
timestamp: March 05, 2025, 01:46:37 pm
content: Quote from: kleiner Rainer on March 05, 2025, 09:07:12 amAcid rain?Damn sulfur dioxide!

author: golden_labels
author_rank: Super Contributor
timestamp: March 05, 2025, 02:51:32 pm
content: Great! 45 minutes of a thrilling detective story.We also have a separatethread about the 0 Ω links(from EEVblog2).

author: Simmed
author_rank: Frequent Contributor
timestamp: March 05, 2025, 04:13:51 pm
content: JBL procurement manager : guys we have a surplus of over 1million 0R smd resistors, let me know some ideas what to do with it ok ?

author: tszaboo
author_rank: Super Contributor
timestamp: March 05, 2025, 05:06:13 pm
content: can someone post a link to that service manual please?

author: temperance
author_rank: Super Contributor
timestamp: March 05, 2025, 05:28:13 pm
content: The resistor in top right corner solder joints looks like it wasn't heated properly during production. The resistor termination looks untouched to me.For the "etched" away trace. I've seen PCB's with acid trapped underneath the solder mask causing all sorts of problems from shorts between traces to open traces.Edit: if those things are build down to cost. Then why are there ferrite beads on the lines for the push button lines? I mean there are (not on this page of the schematic) resistors going to whichever supply voltage powering the micro controller and the voltage divider outputs are going to an ADC. The capacitors such as C1853 shouldn't be there at all. You only need an RC low pass towards the ADC. 1 resistor and 1 capacitor instead of all the ferrite beads and all the capacitors.An other problem with this construction is the very low current trough the switches.Edit 2: the service manual after googling twenty seconds:https://adjuntos.yoreparo.com/default/0006/72/b7b4200db612927fec6dc038ae1fd9922dfbbc47.pdfBeware, it seems to be drawn in Orcad

author: TheSteve
author_rank: Unknown
timestamp: March 05, 2025, 06:23:54 pm
content: Great vid Dave! See, we need more repair videos.And yes it takes a lot of broken stuff to get good vids, that is the challenge.

author: richnormand
author_rank: Unknown
timestamp: March 05, 2025, 10:44:58 pm
content: Re: broken trace.You mentioned a possible liquid spillage. Yet nothing was found around the keys and other mating pieces or on the membrane itself.Similarly you could see the trace all around when you talked about the seal around the membrane.Looks like the break on each side of the trace is pretty sharp. Have you looked at the membrane to see if the missing part of the trace might be embedded in a glue that was all around the edge?These units suffer lots of low frequency vibrations and this could be metal fatigue with the trace glued at that spot vibrating all the time, or someone dismantled the unit before and ripped it out?Interesting detective work.You may have saved it from an early trip to the junk heap.Cheers.

author: JoeyG
author_rank: Regular Contributor
timestamp: April 14, 2025, 03:39:58 am
content: Liquid Damage to an electronics product should not be a warranty repair as the liquid can seep under IC's and other places and Electrolysis take place. Often even a full clean of the PCB to remove moisture/rust and Electrolysis can not be guaranteed and the effort to remove all ICs as not financially viable

author: Bettingbennie
author_rank: Newbie
timestamp: September 15, 2025, 04:17:31 pm
content: Hello, does anyone know what the problem might be?The speaker sometimes won't turn on. The battery has 8 volts, and after unplugging and reconnecting the battery, I can turn the speaker on. All the buttons work, except for the Bluetooth one. Pressing it briefly or holding it down doesn't work. When I press the Bluetooth button, the battery lights do come on briefly. There's also no pairing sound en light when pressing the Bluetooth button. It's also not in demo mode. I've also tried several complete resets, but without success.

author: EEVblog
author_rank: Unknown
timestamp: September 16, 2025, 02:04:32 am
content: Quote from: Bettingbennie on September 15, 2025, 04:17:31 pmDefinitely not a keypad PCB fault then if the button is actually detected.Service manual is here:https://www.eevblog.com/files/JBL-Partybox-310-Service-Manual-v1-4.pdf

author: Bettingbennie
author_rank: Newbie
timestamp: October 09, 2025, 08:35:57 am
content: Thanks, I've replaced both pushbutton circuit boards and tested a new battery, but unfortunately without success.Could it be the motherboard? If so, can I simply replace it, or does it need to be updated afterwards?According to JBL/Harman customer service, it's not possible to manually update the JBL 310 via USB. Only certified installers can do this. Is it worth trying all of this?

author: EEVblog
author_rank: Unknown
timestamp: October 10, 2025, 05:55:12 am
content: Quote from: Bettingbennie on October 09, 2025, 08:35:57 amI can't think of any reason why you couldn't just replace the motherboard.