Cordless Shaving Machine Repaired
Received PRITECH RSM 1505 shaver for repair problem stated Not working no power ON.
I pressed button it is not showing any life no charging LED display, checked cable comes along with & found it Ok. Now time to open it for further inspection.
The back cover has been removed, but we need to take the entire unit out of the outer casing.
Using pray tool on gap in edges I managed to remove the unit out. Now here I got access to the PCB side
Removed 4 screws from the top transparent plastic & reached to PCB.
First checked Battery Voltage it is not showing any voltage.
Now connected the battery on the charger on PCB on various point I am getting near4 v but not getting any voltage on battery connected point. Assumed because of this reason battery is not charging.
After removing the battery, I connected the charging cable and pressed the on/off switch, but the problem persists; the unit is still not turning on. It should work directly on the cable power, but that’s not happening in this case. Some units nowadays work directly on power from the cable, but some don’t due to their circuit design. Battery also show 0v no sign of life.
Now it is time to inspect the circuit. On tracing I found one diode Marked with D2 is dry soldered.
I checked the condition of the diode it is showing short.
So for testing I removed the diode out of the circuit
Checked Diode out of the circuit it is showing OK. Checked surrounding Components, some of them are showing short may be due to design of the charging circuit. So soldered the same diode back.
further I connected external Battery for testing (for testing battery operated device I always use the working good battery I salvaged from old bad Laptop Batteries). I connected the external battery & turned On the device & it the unit is Power up.
Battery charging indicator showing 44%, Now connected the device on charging and after 1 hour I found battery is charged up to 96 % indicates charging process is also good.
Laptop battery I used for testing is 18650, it is bigger then what original used of AA size so this will not fit inside.
I arranged the Battery for replacement from my nearby part supplier.
As you can see, this battery has a BMS circuit with a cable inside, so we decided to cut the wire to a shorter length so that the battery would fit inside easily.
I removed top plastic sleeve cut the wires & split the cable in both direction & soldered on the circuit. I turned On the unit & it is powered ON. This new battery is showing 77% charged.
After the final assembly of the device, I put it on charge, and a few minutes later I noticed that the battery percentage was increasing. I checked the charging voltage on the battery, and it showed 4.2V, which meant the unit was working correctly and ready for delivery.
I’m not entirely sure why the charging voltage wasn’t showing on the faulty battery at that time. Anyway, I was in a hurry to leave, so I couldn’t investigate the cause further. The device was then delivered to the customer.
This article was prepared for you by Yogesh Panchal who works as a Computer Hardware Engineer in Mumbai India.
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Note: You can check his previous repair articles on Saregama Carvaan Mini Bluetooth Radio Distorted Sound Problem
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Parasuraman S
January 24, 2026 at 9:45 pm
Very professionally fixed! Many thanks for sharing with every minute detail!
Yogesh Panchal
January 27, 2026 at 11:04 pm
Thank you! Sir
Albert van Bemmelen
January 24, 2026 at 10:38 pm
Excellent repair by replacing the original defect litium-ion battery!
Sadly they often only use smaller size batteries in shavers why the bigger standard li-ion 18650 cells will never fit.
Yogesh Panchal
January 27, 2026 at 11:25 pm
Thanks! Albert,
later on i found Battery model initial here is not manufacturer, it is Type of Battery.
I — Lithium-ion rechargeable,
C — Cobalt-based cathode chemistry,
R — Round cell shape.
and Battery which i replaced it's initial KP is indicates Manufacturer.
Mark J
January 25, 2026 at 4:07 am
Yogesh good job on the Cordless Shaving Machine repair. I just bought two of those 14500 3.7v LI-On batteries. They were for my ESR meter.
Yogesh Panchal
January 27, 2026 at 11:30 pm
Thank You! Mark J
Please refer to my comments to albert.
Waleed Rishmawi
January 26, 2026 at 2:48 pm
yes these batteries go bad and the problem finding one that has the same specs and at the time time fit in this tight place. you managed though and got it done. have a blessed day
Yogesh Panchal
January 27, 2026 at 11:30 pm
Thanks! Waleed
Maurice
January 28, 2026 at 3:18 am
Nice fix. But the shaver is a shameless copie of a philips shaver.
Yogesh Panchal
January 28, 2026 at 3:56 pm
Thank you! Maurice
Copies does not make difference if provide Good Build Quality.