B6287, I can’t put it up!

Thread Starter

Lindembruck

Joined Feb 28, 2016
46
Hi All

I bought 10 parts of B6287, (new sealed in tape), in the internet site from China, but in true, I bought the MT3608 and they shipped me this on.
I asked money back and got because item was not as described.

After some time, I did a test with it in my lab.
I did a PCB as need, I bought the parts need and mount the PCB as need.
In the net, people tell about it be the same as the part SY7208 and others tell be same as others.
In true, it looks be unique and no datasheet up in the internet for download.

It works fine if not load but lost voltage if get a load.

You can read the only one I found link below, after translate with the Google Chrome:

https://misoji-engineer.com/archives/6037806.html

If someone can try to solve the unexpected response, the no power, please, give us your contribution.

Annexed:
Schematic,
PCB,
Oscilloscope Print
PCB Pic x 3
Chip Pic x 3 (both side),
Tape Pic x 1

Condition:
2 x AA Alkaline,
1 x 1N4148 to protection,
1 x 62 ohms resistor load,

Information:

Chip print: B6287Z

Oscilloscope: OWON SDS7102V full band:
Chanel 1 Red: Tuned for -1V connected to input
Chanel 2 Yellow: Tuned for -1V Connected to output
Horizontal: 200us

Inductor: 22 uH CD43
Diode: SS310
Input caps: 3.000 uF Electrolytic + onboard 10 uF ceramic
Output caps: 2 x 10 uF

VOUT = VREF x (1+R1/R2)
Internal Vref = 0.6 V

Output without load, 5.1 V
Output power with load (62R): 47mA
Oscilloscope show 647.408 Hz in the output

Thank you in advance.
 

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dl324

Joined Mar 30, 2015
13,836
It works fine if not load but lost voltage if get a load.
I wouldn't consider that working "fine".

That's what happens when you buy electronic components from China and they didn't come from an authorized reseller. AliExpress, Alibaba, eBay, Amazon - if it ships from China, it's likely counterfeit. They'll soon get wise to this and start shipping, or saying they're shipping, from places other than China. Then all we'll have to go by is unbelievably low prices.

Post some well focused close-up photos of the top and bottom of one of the parts and I'll see if it has any of the well known clues that it has been remarked.
 

Thread Starter

Lindembruck

Joined Feb 28, 2016
46
Hi dl324.

Thank you to write.

I upload the pictures editing the post.
I think, there are all you ask.

I only give you the feed back now because I was out from the lab.

Waiting from you.
 

Thread Starter

Lindembruck

Joined Feb 28, 2016
46
I upload a new one pic from the chip to be clear to see the mark.
I clear on of the pic not substantial. A one of the tape inside the plastic bag from my stock.
Thank you
 

dl324

Joined Mar 30, 2015
13,836
I upload a new one pic from the chip to be clear to see the mark.
I clear on of the pic not substantial. A one of the tape inside the plastic bag from my stock.
This looks to be counterfeit to me.
upload_2019-2-25_7-50-43.png
I haven't seen any manufacturer markings that looked like this.

The black area on the top doesn't match the bottom. Because this is molded, the surface of the top and bottom should be similar.

The pin 1 indicator should be a molding impression. This one was burned with a laser.

The leads appear to be pitted on top and bottom. On dip parts, the pitting is limited to the top by sandblasting the part to remove the original markings so it can be blacktopped and re-marked. For smaller parts, they may blast the whole part. In any case, there should be no pitting.
 

pmd34

Joined Feb 22, 2014
520
This:
https://cdn.datasheetspdf.com/pdf-down/S/D/B/SDB628-SHOUDING.pdf

Appears to be the original data sheet for the product you have, its a Chinese manufacturer, and the marking looks fine.

I cant see anything obviously wrong with your circuit.
Just some general comments: Its unclear how fast your choice of diode can actually switch (it seems to be a habit of some of the manufacturers to not list it!) - you could try a different diode. It seems like you have wires soldered to your inductor, which could change the value significantly.
Do your batteries actually have enough power in them, as i see the IC has an undervoltage lockout @ 1.98V.

You say it works without a load, is it running at the correct frequency 1.2MHz as your scope trace seems very slow for anything but a failed start up pulse.

What is the voltage on the feedback pin, with and without load.. what if your try a larger load resistor.. 100 Ohms for example..
 

dl324

Joined Mar 30, 2015
13,836
Appears to be the original data sheet for the product you have, its a Chinese manufacturer, and the marking looks fine.
I disagree. Look at how the letters aren't square on the part in post #5. I've seen some genuine parts with sloppy markings, but not as sloppy as this.
 

dl324

Joined Mar 30, 2015
13,836
Here are some photos of genuine parts that I obtained from an authorized reseller. Magnification 60X with my Intel Microscope toy:
upload_2019-2-25_17-50-24.png
Didn't realize that the 6 pin package didn't have a mold mark for pin 1.
upload_2019-2-25_17-50-47.png
This one has a mold mark for pin 1, but I just noticed that it's easy to see it as a bump.

The graininess and colors are artifacts from the microscope program. I need to get a lens for my camera.

Less sophisticated counterfeiters use a blacktop that can be removed with acetone.
 

Thread Starter

Lindembruck

Joined Feb 28, 2016
46
Hi all!

I has reading your posts and thinking about.

About other diodes, I used first a new SS14 with same result.

I changed the chip (SDB628) and do the same result too.

And about the possibility to get burned in the soldering process?
I used a Air Hot torch with 260 degrees model YIHUA 898D+
With SMD soldering paste.

Thank you.
 

Thread Starter

Lindembruck

Joined Feb 28, 2016
46
https://www.yoycart.com/Product/548578993550/

the above has some spec's.

I don't know why you don't breadboard it first? And boost/buck regulators work fine on breadboards, I do this all the time.
Hi!

To me is a lot easy to make a test board because I have all I need from the design, the litho film, burning and etching. A protoboard develope very bad contacts and all they are in a box in the shelf. I need the PCB ready and operating to be used in other projects.

Thank you.
 

Thread Starter

Lindembruck

Joined Feb 28, 2016
46
You should be OK with the hot air gun I think, can you try the other tests, different load, look for the 1.2Mhz etc.
Hi!

Without load, it looks OK but from little or big load, do the same problem, NO POWER OUT ! The frequency is ever the same 650 KHz.

Thank you
 

pmd34

Joined Feb 22, 2014
520
What is the input voltage, with and without load?
Also check your inductor is the correct value and not 220uH for example
 

Thread Starter

Lindembruck

Joined Feb 28, 2016
46
What is the input voltage, with and without load?
Also check your inductor is the correct value and not 220uH for example
Hi! Thank you!

I has been try many, from 2 battery AA to 5V power supply.
I changed inductor, more, I measured it with meter.
First running, was with a new one 4R7 inductor as all.
Second running, with 22uH measured and in the end, running with PCB external 22uH inductor.
In the DataSheet page 6 anexed as picture here, tell about the Inductor and other parts.

With 4R7 inductor, it do not fly the voltage over the power supply.
With 22uH inductor, get run up but do not have power.

The frequency do not change from 647.408 Hz as show in the oscilloscope print.

About input voltage changes, with or without load, if with power supply, no changes but with battery change a little.
You can see in the Oscilloscope measure print screen the run with load.

Pay attention in the Oscilloscope Print because the red is input and yellow is output but both are tuned 1 square down the mid, what represent -1V where start horizontal line.

Thank you very much.

Pictures:
1 - Reset
2 - Measuring
3 - Part measured
4 - SDB628 DataSheet page 6

At this moment, no more information but all you, can ask some test or experimentation if need to clear this cloud.
 

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Thread Starter

Lindembruck

Joined Feb 28, 2016
46
This:
https://cdn.datasheetspdf.com/pdf-down/S/D/B/SDB628-SHOUDING.pdf

Appears to be the original data sheet for the product you have, its a Chinese manufacturer, and the marking looks fine.

I cant see anything obviously wrong with your circuit.
Just some general comments: Its unclear how fast your choice of diode can actually switch (it seems to be a habit of some of the manufacturers to not list it!) - you could try a different diode. It seems like you have wires soldered to your inductor, which could change the value significantly.
Do your batteries actually have enough power in them, as i see the IC has an undervoltage lockout @ 1.98V.

You say it works without a load, is it running at the correct frequency 1.2MHz as your scope trace seems very slow for anything but a failed start up pulse.

What is the voltage on the feedback pin, with and without load.. what if your try a larger load resistor.. 100 Ohms for example..

Sorry to do not give you your answer. Here it is.
Oscilloscope tuned to:

Red Feed Back pin 200mV Resolution
Yellow OutPut 1V Resolution

Both channels tuned to Vertical -1V

Picture 1: 60 ohms Load
Picture 2: No Load
Power Supply: 2 x AA Alcaline with both 3V

Remember the Diode 1N4148 in the Input to protect Reverse Voltage in tests.
 

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Thread Starter

Lindembruck

Joined Feb 28, 2016
46
Here are some photos of genuine parts that I obtained from an authorized reseller. Magnification 60X with my Intel Microscope toy:
View attachment 170997
Didn't realize that the 6 pin package didn't have a mold mark for pin 1.
View attachment 170998
This one has a mold mark for pin 1, but I just noticed that it's easy to see it as a bump.

The graininess and colors are artifacts from the microscope program. I need to get a lens for my camera.

Less sophisticated counterfeiters use a blacktop that can be removed with acetone.
If from Authorised Reseller, is not mater because today all one do its jokes to make money.

I have one reseller who tell be all only original parts from authorised but the parts is the same in quality control as all from AliExpress.
 

dl324

Joined Mar 30, 2015
13,836
If from Authorised Reseller, is not mater because today all one do its jokes to make money.
That makes no sense at all. It's unlikely that an authorized reseller would ever consider ripping their customers off to save/make a little money. That would be committing financial suicide.
I have one reseller who tell be all only original parts from authorised but the parts is the same in quality control as all from AliExpress.
I'm going to disagree with that too. Authorized resellers only buy from reputable sources. AliExpress sellers aren't bothered by selling counterfeit merchandise. I'll buy assembled components from AliExpress, but not individual parts; unless a counterfeit/remarked/salvaged part is okay. Wire, connectors, tools are fine as long as you aren't expecting anything of the same quality that you'd get from reputable sources that would cost many times the AliExpress price.
 
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