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 speculation
02:57 – Teardown
06:23 – Is it a firmware lockup issue?
07:17 – Checking the power switch
09:13 – Main PCB’s
10:52 – Hello IT, have you tried turning it off and on again
11:46 – PCB microscope inspection
13:39 – Bench testing and, thou shalt test voltages
16:31 – Looking at the keypad PCB again
17:41 – Replicate the fault using an external PSU
22:55 – Schematic, we have Schematic!
24:14 – The power flow block diagram
28:44 – The penny drops
29:45 – Design TIP
32:04 – Without the schematic I’d be chasing a red herring down a rabbit hole
33:10 – Manual Bypass time to get it working!
34:50 – I called it at the start, but assumed incorrectly
36:33 – OK, let’s trace WHERE this fault actually is
37:41 – No, it’s can’t be, surely not…
39:52 – But WHAT caused it?
42:05 – The repair
44:20 – Assembly back together and testing

HP 1740A oscilloscope repair:
Part 1: https://www.youtube.com/watch?v=Cmz8bzUsj7E
Part 2:

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