INSKAM Microscope USB port issue

[lcdcaps1]

Hi
All
Does anyone have a INSKAM 7 inch LCD digital microscope
I have a weird issue on the one I have where the USB port does not output enough power because when I connect a USB light or the ring light the light output is always really dim
The ring light when connected to the microscope USB port is at the lowest brightness and turning the brightness knob makes no difference
I have tried different cables and different USB power adapters

I have confirmed there is nothing wrong with the ring light and the other USB light by plugging them into another USB source other than the microscope and they work fine and ring light brightness works

Has anyone had any issues with this before
Does anyone have any schematics or board view or photos of the board

Thanks all

[stj]

most usb microscopes you dashcam type circuits, it probably has a usb supervisor chip on the 5v rail that limits current.

[lcdcaps1]

most usb microscopes you dashcam type circuits, it probably has a usb supervisor chip on the 5v rail that limits current.

Thanks for the reply
I'll try and get into it and look

[lcdcaps1]

I have just noticed my photos of the microscope. Did not attach. I have attached again.
I am trying to get inside to have a look but after removing the screws it is still tight

Has anyone got the same or similar microscope, please. The inside boards are most likely the same or similar throughout the diffirent models
Thanks all

[lcdcaps1]

I plugged in a USB amp meter into the USB port and got nothing showing
I tried a few and tested on other devices
I found this very strange

It is as though the USB port is shorted or loose
I do not understand why there is no voltage showing because there must be some voltage output as the LED ring light is being lit up
Still trying to see how to get into it
Removed the screws but still very tight

[lcdcaps1]

I plugged in a USB amp meter into the USB port and got nothing showing
I tried a few and tested on other devices
I found this very strange

It is as though the USB port is shorted or loose
I do not understand why there is no voltage showing because there must be some voltage output as the LED ring light is being lit up
Still trying to see how to get into it
Removed the screws but still very tight

What could cause the USB Ammeter show this behaviour
Has anyone seen this issue before

[lcdcaps1]

Hi
Any ideas from anyone
Thanks

[lcdcaps1]

I have finally managed to get inside.
I have attached some photos of the board

[stj]

the 4056 is a classic lithium charger chip

[lcdcaps1]

the 4056 is a classic lithium charger chip

Thanks for the reply
the battery is charging
My suspects are the two small sot-23 components
I am trying to find some replacements but I cannot find any information on the 23ax component
what substitutes can i use In replace of 23ax and 1am
thanks

[SMDFlea]

Thanks for the reply
the battery is charging
My suspects are the two small sot-23 components
I am trying to find some replacements but I cannot find any information on the 23ax component
what substitutes can i use In replace of 23ax and 1am
thanks

Can you post a better picture of the 23ax IC , is there an underscore under the A , 23AX

[lcdcaps1]

Can you post a better picture of the 23ax IC , is there an underscore under the A , 23AX

I am attaching another photo,
best as I can get
No underscore

Any ideas where I could find such components
Any scrap boards for example

Also any substitutes available
Thanks

[lcdcaps1]

Here are photos of the other side of the board
I am trying to find more details of this component, seems like a voltage regulator but cannot find a datasheet
What I find strange is that the USB port is working but not as it should
Also when I plug in a USB tester it shows nothing

[lcdcaps1]

Studying the boards front and back I can see there is a chip which I believe is to be a ln2220par. The datasheets I am finding is all in chinese
From what I can establish it is a voltage regulator
If the USB port was outputing voltage I should see this on the USB meter so I can only assume that when I plug in a USB light and the Light is dim is because it using the battery voltage or the voltage from the Type c port that is used for charging and running the microscope of the Type C cable
Can anyone please give some input in regards to this
Has anyone had issues like this before

I will really appreciate any input
Thanks

[lcdcaps1]

As an experiment, I disconnect the battery and the USB light did not work when plugged into the USB port
This would mean that there is no voltage or current output from the USB port and can only think that the ln2U220par is responsible for supplying voltage to the USB port
Any help will really be appreciated
Thanks

[m1ch43lzm]

The LN2220PAR looks like a step-up boost converter, your microscope is powered by a lithium battery? If yes that may be to boost the voltage for the usb port

This AliExpress listing claims to be a "replacement" of FP6291 and MT3608, both step-up converters

https://aliexpress.com/i/1005008340248788.html LN2220PAR MT36291 SOT23-6 24V Replace FP6291 MT3608

Attached the MT3608 and MT36291 data sheets, only difference is a current limit pin 6 which may be left floating on the MT36291, I can find MT3608 modules already assembled on a PCB very cheap on ali for less than $1

[lcdcaps1]

The LN2220PAR looks like a step-up boost converter, your microscope is powered by a lithium battery? If yes that may be to boost the voltage for the usb port

This AliExpress listing claims to be a "replacement" of FP6291 and MT3608, both step-up converters

https://aliexpress.com/i/1005008340248788.html LN2220PAR MT36291 SOT23-6 24V Replace FP6291 MT3608

Attached the MT3608 and MT36291 data sheets, only difference is a current limit pin 6 which may be left floating on the MT36291, I can find MT3608 modules already assembled on a PCB very cheap on ali for less than $1

Thanks for the reply. The microscope is powered by Type C that charges the rechargeable battery
The microscope can be used from the rechargeable battery without being plugged in

[m1ch43lzm]

Measure voltages here

At Vin it should be the battery voltage, Vout should be 5v

Not sure about this resistor, is there a hole in it? To the left of that resistor is your 5v output for the USB port, measure resistance across it, it should be a very low value
Measure resistance across the caps below, shouldn't be shorted




One of the many readily available MT3608 modules on the online stores, the layout is very similar, you can harvest the IC from there if it's determined to be faulty

EDIT: measure the current draw of your USB lights when plugged in to a regular USB power adapter, if it's too high it may have blown that resistor
Maybe that USB port is supposed to work only with a USB stick for saving the pictures/video

[lcdcaps1]

Measure voltages here

At Vin it should be the battery voltage, Vout should be 5v

Not sure about this resistor, is there a hole in it? To the left of that resistor is your 5v output for the USB port, measure resistance across it, it should be a very low value
Measure resistance across the caps below, shouldn't be shorted




One of the many readily available MT3608 modules on the online stores, the layout is very similar, you can harvest the IC from there if it's determined to be faulty

EDIT: measure the current draw of your USB lights when plugged in to a regular USB power adapter, if it's too high it may have blown that resistor
Maybe that USB port is supposed to work only with a USB stick for saving the pictures/video

Thanks for the reply
I was going to measure that resistor
I will wait for the new parts

The USB port is meant for the ring light and was working until one day it was not
Thanks again