Cambridge audio MINX Go wont turn on - Page 1
Forum section: electronics / repair

author: Veketti
author_rank: Regular Contributor
timestamp: January 05, 2025, 10:11:38 am
content: Dear All,I've got this bluetooth speaker which simply stopped turning on after playing a while with full volume. Power plug connector is ok, I checked that. I've measured the power rails and 5V as well as PAM8620 power supply 16V are present. When I press the power button I get 5V to the PAM8620 pin5 5V Analog Supply as well as to pin 23 shutdown signal. But immediately I stop pressing the button these voltages are gone. I tried connecting the shutdown signal to 5V permanently as well, but the device is not turning on, so my undestanding is that the latching circuitry is not the culprit. There is also uC on board Silan SC51P0304SA1 which I didn't find any datasheet for. Maybe it is the one to control the power latch? Could it be that the amplifier chip PAM8620 is toasted or the uC? Is there something else I could try to troubleshoot to narrow the issue?Thank youEdit:added photo

author: fzabkar
author_rank: Super Contributor
timestamp: January 05, 2025, 04:46:38 pm
content: Quote from: Veketti on January 05, 2025, 10:11:38 amCould this be a similar IC?https://datasheet4u.com/datasheet-pdf/SilanSemiconductors/SC51P03A05SC1G/pdf.php?id=1424154Quotehttps://www.diodes.com/assets/Datasheets/PAM8620.pdf

author: Veketti
author_rank: Regular Contributor
timestamp: January 06, 2025, 09:47:48 am
content: I measured all the transistors following Mr. Carlson'svideoand they all were ok. Then measured also all capacitors and found one presumably capacitor, this marked C912 which measured short (0.2ohm). It's white and the silkscreen print tells C so I assume it to be capacitor and not inductor or like. However the white color makes me wonder. Should I try removing it and then testing whether it works?This Capacitor is in that 5V buck converter circuitry and I was able to measure the 5V present at the PAM8620 amplifier so that makes me wonder whether this actually makes any differences..edit: it seems to be connected to the trace between theAP1509output and inductor. According to the AP1509 datasheet example schematic there is no other components than Schotty diode there, so its purpose is unknown?

author: Sorama
author_rank: Frequent Contributor
timestamp: January 06, 2025, 09:55:28 am
content: Desolder that cap and measure the pads on the pcb to see if there is still a short.And also the capacitor.

author: Veketti
author_rank: Regular Contributor
timestamp: January 06, 2025, 11:12:44 am
content: Desoldered that C912 and those pads are still shorted. Measured that white "capacitor", it is not shorted and measured 2 pF. What might be the purpose of that? Makes zero sense to me. Is there any point in soldering it back as it is useless?

author: Veketti
author_rank: Regular Contributor
timestamp: January 14, 2025, 07:54:07 pm
content: Got some components and replaced the PAM8620 amplifier. Still wont turn on.. I'm not sure though did I fry the new one as it wasn't easy to solder new one with the heat gun.. I got also some of those op-amps (JRC4558) that is populated on the board so should I start changing them? I don't know is there a way to measure them whether they're good or not. However my assumption is that they're in the sound input side so they shouldn't have anything to do with the device turning on. Am I somewhat correct?