Mammotion charging station repair - Page 1
Forum section: electronics / repair

author: Kaar3l
author_rank: Newbie
timestamp: August 02, 2025, 09:53:42 pm
content: Hello!I got a charging station that has a blown component on the pcb.I am having hard time to find what component it might be?The component has Marking: B 075. After I removed the component it has S marking under it.It seems to be input component. This B 075 component one side is connected to a diode. Also there is a ic marked: lr358d that appears to be power related.

author: Kean
author_rank: Unknown
timestamp: August 03, 2025, 05:24:12 pm
content: It is possibly a 750mA PTC "resettable fuse", based on the markings and physical shape. Some people/standards use a symbol like an S for a fuse.If the B was lower case, I would say it was "Bel Fuse" brand. Not familiar with any brands that use a big B.The fact is burnt up like that is a concern, and may be a sign of more problems to come if you don't know the original failure cause.Do you have approximate measurements of the original part size?A potential replacement could be the Bel 0ZCJ series which is a 1206 (approx 3.2x1.6mm) package.https://www.belfuse.com/products/circuit-protection/ptc-resettable-fuses/0zcj-series

author: Kaar3l
author_rank: Newbie
timestamp: August 03, 2025, 08:47:48 pm
content: This component size seems 3,2mm x 6?mm. I still had broken part and it measured 3,2mm. I couldn't determine the length exactly but it seems about 6mm.To me the S sign seems very much fuse. I will try to get about 30V 0,75A fuse for replacement.

author: Kean
author_rank: Unknown
timestamp: August 04, 2025, 03:12:16 am
content: I'd guess 1812 is the closest standard size - that is 4.6x3.2mm. Better to go slightly smaller than get one that is too big to fit.Digikey have stock of the Littelfuse MINISMDC075F/33-2 which is rated to 33V.TME have stock of the Littelfuse MINISMDC075F-2 but that is only rated to 13.2V. They have some others for 30V or 33V like the Bel Fuse 0ZCG0075BF2B.

author: Kaar3l
author_rank: Newbie
timestamp: August 10, 2025, 07:00:11 pm
content: I did get a bigger fuse (by dimensions bigger). Managed to fit it to place. Then I powered it up. Didn't work but the fuse did get hot. Found a chip on the other side that got hot.Chip marking: AeDk.Pin1-GNDPin2-Output +5VPin3- +30V inputPin4-Goes to resistor (possibly a voltage divider)Pin5-Goes to a capacitorPin6-?I tried to find the chip with AI but it failed.This broken chip had GND on all the pins.The chip and layout seemed that it was 30V to 5V power supply.I gave up and used a small chinese power supply board that potentiometer I moved to 5V. Supplied the 5V to 5v pin and connected GND and it seems to work.The board had 5V and 3.3V lines that have leds for identification.Both leds light up when connected the new poer supply.

author: kripton2035
author_rank: Super Contributor
timestamp: August 10, 2025, 07:50:39 pm
content: possible solution :With VIN ≈ 30 V, VOUT ≈ 5 V, and FB likely around 0.8–1.0 V, you’re squarely in the territory of chips like:MCP16301 / MCP16301H (Microchip, 50 V input, 0.8 V ref, 500 kHz)MP2451 / MP2456 (MPS, up to 60 V, 0.8 V ref, 1.4 MHz or 500–750 kHz)LMR16006 / LMR16010 (TI, 60 V input, 1.0 V ref, 600 kHz)What you can do now to narrow it:Measure pin 4 (FB) while powered →• ≈0.80 V → MCP16301 / MP245x family likely• ≈1.00 V → TI LMR1600x familyIdentify pin 6 (BST) → should have a tiny cap (~22–100 nF) to SW (pin 2).If possible, scope SW (pin 2) to read switching frequency; that often nails the exact chip.here are thetypical switching frequencies you’d see on Pin 2 (SW)for the most likely SOT-23-6 high-VIN bucks that fit your 30 V→5 V case. These are ballpark “fixed-freq” numbers; light-load modes can modulate them.TI LMR16006 / LMR16010→ ~600 kHzMicrochip MCP16301 / MCP16301H→ ~500 kHzMPS MP2451→ ~1.4 MHzMPS MP2456→ ~500–750 kHz(family variants)Richtek RT8250/RT8251→ ~1.2–1.5 MHz(variant-dependent)Silergy SY7208/SY7209→ ~1.2–1.4 MHz(common)

author: Kean
author_rank: Unknown
timestamp: August 11, 2025, 03:38:13 pm
content: No idea of what it is based on the marking unfortunately.I don't see an external diode there (unless it is behind the inductor) and the pins do not match up with an LMR16006, so I'd suggest a synchronous buck regulator like the LMR51420 where the pin usage seems to match. This part uses an FB reference of 0.6V.As it isn't powering up (if GND is on all the pins as stated) then you cannot measure the FB pin. I'd suggest to try measure the existing FB resistors, and if not possible then plan to replace them with calculated ones for 5V out with the chosen replacement device.Check the LMR51420 datasheet and maybe do a Webench design/simulation. There are a few similar TI parts, but I think most lower current SOT-26 ones seem to use the LMR14006/16006/51606/54406/54410/etc style pin usage.Edit: Hmm, a 22uH inductor does seem a bit high though for that part and output voltage.

author: gamalot
author_rank: Super Contributor
timestamp: August 11, 2025, 05:02:56 pm
content: Quote from: Kaar3l on August 10, 2025, 07:00:11 pmETA2807https://www.eta-semi.com/wp-content/uploads/2022/03/ETA2807_V1.2.pdf

author: kripton2035
author_rank: Super Contributor
timestamp: August 11, 2025, 05:28:51 pm
content: Quote from: gamalot on August 11, 2025, 05:02:56 pmnice catch ! did you knew this chip already or else how did you find it ?

author: gamalot
author_rank: Super Contributor
timestamp: August 11, 2025, 05:59:18 pm
content: Quote from: kripton2035 on August 11, 2025, 05:28:51 pmI searched on Taobao using the keywords "SOT23-6" and "丝印Ae"