esp8266 hv-628 v1.1

[Baigars]

Hello i have a big problem with esp8266 hv-628 v1.1 boards , they only work if i use arduino examples , if i using wled, tasmota or espeasy the wifi do not show up , sometimes it shows but its is impossible to connect to something.
its clearly the hardware problem, but how to know that it is i tried switching eeprom between node mcu node works like charm, but hw 628 nothing.
There is some versions of this board with antena wired to grown directly , but after fixing that stil nothing.
I tried to reverse engineer the board, but had no idea what to look for. What can be the thing what forbids this board from working with espeasy? Sorry maybe not the right forum to ask, but im do not know where to ask else, the scraping then is no option i have then around 25.
thanks for any suggestion.

[Ath]

First to check would be the power source of the board. Can you try with a different USB cable for powering the board? And preferably even a completely different power source (computer USB instead of separate power supply or the other way around)

[Baigars]

done that, already nothing helps.

[TD-er]

The following 'trick' or 'test' may sound a bit weird, but I've seen similar boards before and I believe the antenna impedence is matched really poorly.

Please try pressing a finger or your thumb firmly on the antenna while trying to connect to WiFi.
You may probably even feel that there is a temperature difference on the antenna.

If you manage to get a WiFi link by doing this, then you know you have been sold utter garbage.

The manufacturer either has made a very poorly tuned antenna on the PCB, or some matching components (capacitor/resistor) has been swapped for one with a wrong value or maybe even wrong type (e.g. cap instead of resistor or the other way around)

[Baigars]

Did get thermal camera there is pictures

,

and video https://youtu.be/5DaEsUK9Vo0 the antena does not heat up at all, did try the thumb trick nothing helps. some other solutions or experiments?

[Baigars]

Did notice the strange heat los,s but its crystal with metal surface it reflects infrared, i think i did move away from reflection.

[TD-er]

It is very hard to get a proper thermal reading on reflective surfaces.

However an ESP chip which heats up to near "cannot touch anymore" temperatures is for sure not how it should be.
Are you sure the reported temperature of 47.7C is correct?
Typically 50C is about as hot as one can tolerate holding in your hand.

An ESP8266 should hardly feel hot at all when running.

[Baigars]

there is scamatic, (did not finish to make it readable and correct exact values) https://drive.google.com/file/d/1bXi1Zu ... sp=sharing
and here is bcb https://drive.google.com/file/d/1pbUjBD ... sp=sharing
here some preview on gnd line

[Baigars]

It is very hard to get a proper thermal reading on reflective surfaces.

However an ESP chip which heats up to near "cannot touch anymore" temperatures is for sure not how it should be.
Are you sure the reported temperature of 47.7C is correct?
Typically 50C is about as hot as one can tolerate holding in your hand.

An ESP8266 should hardly feel hot at all when running.

the working esp nodemcu v3 is around 39 c , the hw 628 is around 46, but if i torch it is just little warm hand temperature around 36c so it must be accurate.

[TD-er]

I don't have Eagle, so I can't open your schematics.

I suspect they may have switched some parts close to the antenna feed in point.
See: https://www.espressif.com/sites/default ... nes_en.pdf
PDF page 11, marking at the page itself 6/32

A close-up of the antenna impedance matching circuit can be found on PDF page 15 (section 1.4.5) and a close-up of the reference PCB design surrounding the antenna on PDF page 24 (1.6.3)

As you can see there should be 2 capacitors, which are both connected to GND on one end and both opposite to a coil.
And to really add to the confusion, the schematic shows 2 capacitors but marked them as L1 and L2 and the coil is marked as C4
On the PCB there is at least 1 capacitor missing ("L2" in the reference schematic) and I suspect they may have swapped L1 and C4 in the reference schematic.
Or maybe even replaced one by a resistor or used the same inductance value as for L3 to save a fraction of a cent.

I really doubt they knew what they were doing when copying the design.

I just found some ESP RF test tool on the Espressif site: https://www.espressif.com/en/support/do ... d%5B%5D=14
I have never used it, but it seems like they have some binaries included and the tool seems to allow to set some offsets.
So maybe it can help you find out more about how bad the antenna is tuned.
But I think it isn't really worth doing as the design is clearly bad and makes you wonder what else they messed up if you eventually may get the antenna stuff working.