Need Help To Repair Sharp Bluetooth Speaker PS920 - Page 1
Forum section: electronics / repair

author: RaymondRosas
author_rank: Contributor
timestamp: June 25, 2024, 03:29:37 am
content: Hi everyone,I could really use some help with fixing a Sharp Bluetooth speaker with the model number PS920. It's not turning on, and I'm hoping to get some suggestions. I've been troubleshooting and found that the power supply is giving a 14-volt output, but there's no DC output from the battery connection and DVCC5V.I've already replaced a faulty capacitor, and the battery is completely drained. I tried supplying 12 volts from the battery connection, but still, there's no DC output. I've tested components like transistors, MOSFETs, and diodes using the FADOS9F1 tester, and they all seem to be okay. Right now, I suspect that the IC WB8PA76BE is the issue, but I can't seem to find any datasheet for it.Would anyone happen to have a datasheet or schematic diagram they could share? Any help would be greatly appreciated!

author: fzabkar
author_rank: Super Contributor
timestamp: June 25, 2024, 09:43:48 pm
content: That 14-pin IC looks like a microcontroller.https://pdf1.alldatasheet.com/datasheet-pdf/view/1132952/FEELING/FM8PA76BEP.html(FM8PA76BE)https://crossic.com/wp-content/uploads/2021/10/fm8pa76_1v30_003-1.pdfhttps://m.jtm-ic.com/aspcms/news/2016-6-7/3234.html(CX8PA76BE = 14-pin OTP device)

author: gabiz_ro
author_rank: Regular Contributor
timestamp: April 25, 2025, 12:03:14 pm
content: old topic but maybe usefull info.Some problem also with PS920, found that is similar with PHILCO PHT-5000, that schematics is available.

author: RaymondRosas
author_rank: Contributor
timestamp: April 28, 2025, 03:15:42 am
content: Hi everyone!Quick update — the block diagram is all set and working perfectly, 100%! Tested it and everything’s running smooth.Thanks a lot for all the help and tips, really appreciate it!You guys are awesome!Schematic Diagram:220V AC|+------------+| Charger | (Converts 220V AC to DC output)+------------+|+------+------+------+------+| | | |(R) (G) (DC -) (DC +)| || +----->|----+| (Diode) || |+------|---------------+------+| | |  | | (+)(-)Load LoadExplanation:220V AC goes into a charger that converts it to DC output.Terminal 3 (DC Negative) connects directly to the battery negative and the negative side of the switches.Terminal 4 (DC Positive) passes through a diode first (for protection against reverse current) before going to the battery positive and the switches' positive side.The diode blocks any reverse current from the battery back to the charger.The switches are used to control the output or loads.

author: gabiz_ro
author_rank: Regular Contributor
timestamp: April 28, 2025, 06:01:23 am
content: Quote from: RaymondRosas on April 28, 2025, 03:15:42 amYour board looks like mine.Near diode there is a mosfet drived via a transistor from that mcu that cut power from psu to that diode.Pin1 R seems not connected.Pin2 G is a pull down from PSU side when there is some current drawn signal tu mcu to light red led for indicating charging, when current drawn is little mcu say battery full and light up green led.

author: oskimac
author_rank: Contributor
timestamp: May 16, 2025, 06:47:45 pm
content: but what was your problerm?? did you fixed it? mine didnt activate q14 so i bridge it. problem solved. idkw

author: gabiz_ro
author_rank: Regular Contributor
timestamp: May 16, 2025, 09:10:55 pm
content: Can't check schematics now.If Q14 is this one I bridged too.Controller cut power from PSU and stay on battery even plugged in.A little weak battery and controller start looping on off Vcc power.On controller are some inputs via divider resistors and was protected with zener diodes, 3V3, I found that measured values doesn't reflect expected values based on resistors value so I replaced zener diodes but still same readings and result then I removed zeners and reading values was as expected but still same result.Put back zener diodes and bridged that mosfet and all works fine.

author: oskimac
author_rank: Contributor
timestamp: May 17, 2025, 03:28:09 pm
content: your board is a litle diferent . i think its the same problem but we shorted diferent parts