Author Topic: EEVblog #596 - World's Cheapest Soldering Station - Yihua 936  (Read 70405 times)

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Offline Fungus

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Re: EEVblog #596 - World's Cheapest Soldering Station - Yihua 936
« Reply #125 on: July 14, 2015, 12:20:19 pm »
Yes the Blue wire is wired to the active, not switched, and yes this is fused (as mentioned) prior to the transformer...is this where your heading?  Aka any short the fuse blows?  I do concur.

I'm not sure where I'm headed exactly.

I'm trying to think of a situation where "live transformer primary" is dangerous but where many lives would be saved if it was done 'correctly'.

If you've taken the cover off without unplugging it first and are poking random wires with a screwdriver then ... you could also be doing it with an intact fuse when some other component has failed and the iron isn't getting hot. Maybe you need to learn that lesson the hard way.

 

Offline McBryce

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Re: EEVblog #596 - World's Cheapest Soldering Station - Yihua 936
« Reply #126 on: July 14, 2015, 01:45:23 pm »
In many countries even if it was done "correctly" the plug can still be pushed into the wall socket in both directions (making it "incorrect" again), which is why you learn that you shouldn't "poke around with a screwdriver" if the device is still plugged in.

McBryce.
 

Online wasyoungonce

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Re: EEVblog #596 - World's Cheapest Soldering Station - Yihua 936
« Reply #127 on: July 14, 2015, 11:12:37 pm »
Sorry folks...I had an old timer moment...power active is live at the transformer before the fuse and switch, I wrote it wrong above. |O

My first thought was this item is intrinsically safe because it uses a plastic box and you really cannot touch any live part, but it's not because of the wiring.  Yes it's rare to see transformers short, but I have seen it and bejesus they stink when they go up!  But as you said it's very rare because of the way they are made etc.  But there again, if they mfgr cannot wire the switch and plug right is the transformer any better.  Well their grounding wasn't. 

Which bring me to my finalisation, yes this is not right, yes it presents little danger but it does present some hazards.  Yes it would fail Australian safety standards but is effectively safe enough for users.  But I guess I am not one of the "most" users...I pull things apart (and sometimes cannot get them back together! ;D) to check, correct and improve.

In my case, with this soldering station, I tossed all of the insides because it was under performing and make my own, changing the switch and lead of course ;)   
 
Certainly I wasn't particularly aware that OS plugs could be plugged in either way (well not quite I did have some idiot twist the pins of a 110V plug to fit an Australian socket for a light table, plugged it in and bang!), hadn't really thought about it much lately (which I admit is naive) even though I've worked with a lot of French/US Avionic gear, mostly powered by 115V 3phase.  But yes US 110V plugs would be a nightmare also aware they have 220V in some households (for higher powered domestic appliances)....going to look those plugs up now!



« Last Edit: July 14, 2015, 11:14:32 pm by wasyoungonce »
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Offline Mati256

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Re: EEVblog #596 - World's Cheapest Soldering Station - Yihua 936
« Reply #128 on: January 04, 2017, 04:27:07 pm »
Hello. I see there are 110V and 220V versions of this cheap station. Looks like 220V ships from Hong Kong adding time and money to the item. Would I be ok purchasing a 110V and changing the transformer for a 220V 50Hz or the electronics require it to be 60Hz? Would it be better to use a Power Converter (although the ones I can get here don't have a ground connection!)?

What's the secondary for this transformer? 24V?

Thanks!
 

Offline mariush

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Re: EEVblog #596 - World's Cheapest Soldering Station - Yihua 936
« Reply #129 on: January 04, 2017, 05:58:06 pm »
I don't think the frequency's a problem.

There's a 24v or 26v AC winding (i've seen 28v AC in pictures for some stations ) for the heater element  but there's also at least one other secondary winding for 10v AC or something like that, which is meant to power the electronics inside (3.3v or 5v for microcontroller using a linear regulator) and up to 15v for opamp or comparator or whatever it uses to measure temperature and compare with configured temperature limit.
I suppose you could buy a transformer with just one secondary winding and hide inside the case a separate power supply, let's say a small wall adapter to give 12v DC or something like that.
You'd have to open your soldering station and check the circuit to see what it does with the windings coming from the transformer.
 

Offline Mati256

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Re: EEVblog #596 - World's Cheapest Soldering Station - Yihua 936
« Reply #130 on: January 04, 2017, 09:00:03 pm »
Thanks for the answer. More than one secondary? That's new. They have only one secondary in the pictures I have seen.
I could always buy the 110V version, meassure all the secondary coils and buy a custome transformer, but that might end up costing more than shipping it from Hong Kong.  :-DD
 

Offline mariush

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Re: EEVblog #596 - World's Cheapest Soldering Station - Yihua 936
« Reply #131 on: January 04, 2017, 09:19:49 pm »
Thanks for the answer. More than one secondary? That's new. They have only one secondary in the pictures I have seen.
I could always buy the 110V version, meassure all the secondary coils and buy a custome transformer, but that might end up costing more than shipping it from Hong Kong.  :-DD

You can see for yourself on page 4 of this thread, where dude shows the insides of Yihua 937 he bought : https://www.eevblog.com/forum/blog/eevblog-596-world's-cheapest-soldering-station-yihua-936/msg416686/#msg416686
You can see the picture of the transformer, a 24v winding and a 10v winding.
The 10v winding is probably less than 100mA, there's a diode for half wave rectification and a capacitors to smooth out the dc voltage and then a 7805 regulator or something like that takes 7...15v down to 5v ... just for the microcontroller and the lm358 opamp  and the 3 led digits (multiplexed)
 

Offline Mati256

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Re: EEVblog #596 - World's Cheapest Soldering Station - Yihua 936
« Reply #132 on: January 04, 2017, 09:42:10 pm »
Ah, I see. But I'm talking about the 936 here, its analogue. The 937 is digital so it's a different circuit.
 

Offline mariush

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Re: EEVblog #596 - World's Cheapest Soldering Station - Yihua 936
« Reply #133 on: January 05, 2017, 12:40:28 am »
Ah, I see. But I'm talking about the 936 here, its analogue. The 937 is digital so it's a different circuit.

The analogue 936 would still need to power the opamp or comparator with some voltage ... which won't be 24v AC.

Here's the original Hakko 936 schematic... http://dalincom.ru/datasheet/HAKKO_936_schematic.pdf

As you can see, it uses a quad opamp LM324  and it's powered with ~ -5v  and +5v , you can see there it uses two 5.1v zener diodes to create the positive and negative rails for the opamp.

Some third party designs / clones simply use a separate winding keeping the high voltage winding separate, just for the heater.  Or they use better opamps or don't care about opams not being able to get output close to 0v, so they use only ground and positive voltage instead of feeding opamps with negative and positive voltages.
 

Offline nickeevblog10

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Re: EEVblog #596 - World's Cheapest Soldering Station - Yihua 936
« Reply #134 on: May 03, 2019, 01:38:46 am »
 I have an Atten 936 manufactured by Shenzhen Atten Electronics which stopped working and so far have tested and ready to replace the BT137 600 with a NXP BT137 600E.
 After reading through the posts in this thread decided someone might like to see some photos of my version of this solder station and ask two questions and I will put a heat sink under the replacement Mosfet.
In one photo I have marked a vertical rectangle and a circle both in Yellow. I guess the vertical rectangle is showing off.
 The circle is around the area where the Ground was soldered but without first checking precisely where the Ground was soldered I removed it and forgot what I had looked at. All I could remember was it seemed to be soldered to both tracks where you see the ground soldered now. Is this correct and to which track or tracks should the Ground Wire be soldered?

EDITED: In the second photo the Ground Wire in the circle is supposed to connect to either both or to one of the tracks on the board. It is so long ago I removed the wire I forgot how it was connected but remember is seemed to be connected to both tracks. The half of the wire I soldered to the longer left track may not be useful at all because that track comes from the middle solder iron pin, the middle of seven pins, and that track is about 15 mm long connects to no other components on either side of the board. The shorter wire does connect to other components and so connects to other tracks on the board.
So should that Green Ground(Earth I suppose) wire need only be connected(soldered) to the track which has components connected to the circuit on the board?
« Last Edit: May 07, 2019, 06:34:33 am by nickeevblog10 »
 

Offline LucasArg

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Re: EEVblog #596 - World's Cheapest Soldering Station - Yihua 936
« Reply #135 on: May 08, 2019, 12:09:24 am »
How should the zener diode ZD2 be in the schematic of the hakko 936. What would be the correct position?
 

Offline LucasArg

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Re: EEVblog #596 - World's Cheapest Soldering Station - Yihua 936
« Reply #136 on: May 08, 2019, 12:14:54 am »
Hello EEVblog I like your YouTube videos I always look at them although I do not handle English well. Well I would like to know if this circuit of the hakko 936 is going well? I would like to make this station. I read in a comment that the zenner diode ZD2 is wrong or badly placed I would like to know how I would have to mount it. I hope you can help me. Greetings thank you.
 

Offline LucasArg

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Re: EEVblog #596 - World's Cheapest Soldering Station - Yihua 936
« Reply #137 on: May 08, 2019, 12:34:05 am »
Dave takes a look at the world's cheapest temperature controlled soldering station, the $16 Hakko 936 knockoff Yihua 936 from Hobby King.
How does it compare to the older genuine Hakko 926?
Also, thermal capacity comparison testing is done on those two irons plus the high thermal capacity JBC.
Sagan also gives his verdict.
http://en.yihuaxin.com/about.html
Hakko 936 Schematic: http://dalincom.ru/datasheet/HAKKO_936_schematic.pdf

! Private video


Hello EEVblog I like your YouTube videos I always look at them although I do not handle English well. Well I would like to know if this circuit of the hakko 936 is going well? I would like to make this station. I read in a comment that the zenner diode ZD2 is wrong or badly placed I would like to know how I would have to mount it. I hope you can help me. Greetings thank you.
 

Offline LucasArg

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Re: EEVblog #596 - World's Cheapest Soldering Station - Yihua 936
« Reply #138 on: May 08, 2019, 12:36:29 am »
Hakko 936 Schematic: http://dalincom.ru/datasheet/HAKKO_936_schematic.pdf
I believe there's an error in this schematic. Anode and cathode of ZD2 (5.1V zener diode) looks to be swapped in this schematic. If mounted this way the zener diode will be forward biased an only work as a regular diode instead of a reverse biased 5.1V zener diode.


How should the zener diode ZD2 be in the schematic of the hakko 936. What would be the correct position?
 

Offline LucasArg

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Re: EEVblog #596 - World's Cheapest Soldering Station - Yihua 936
« Reply #139 on: May 08, 2019, 12:37:24 am »
The different behaviour of the LED is due to the fact that the heater is driven with PWM, and so is the LED - as it approaches the setpoint the duty cycle reduces, so it looks like it's gradually dimming before it turns off.

Here's an Aoyue 936 schematic, which is a somewhat more complex controller for thermocouple elements (includes a TL431 and an optocoupler - don't know why the latter would be needed, since the iron is already isolated through the transformer):
http://s020.radikal.ru/i706/1304/f7/f05b997dbf33.jpg

Another 936 clone controller, with TL431 but no optocoupler: http://images.people.overclockers.ru/205524.jpg

Hakko 936 Schematic: http://dalincom.ru/datasheet/HAKKO_936_schematic.pdf
I believe there's an error in this schematic. Anode and cathode of ZD2 (5.1V zener diode) looks to be swapped in this schematic. If mounted this way the zener diode will be forward biased an only work as a regular diode instead of a reverse biased 5.1V zener diode.
After looking at the schematic and this: http://cdn.head-fi.org/c/cd/cdd2b519_PCB_Compare.png I think you're right.


How should the zener diode ZD2 be in the schematic of the hakko 936. What would be the correct position?
 

Offline nickeevblog10

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Re: EEVblog #596 - World's Cheapest Soldering Station - Yihua 936
« Reply #140 on: May 08, 2019, 03:31:21 am »
LucasArg...
These two links are not working.
There is many different board layouts for the imitation 936 boards.
Mine is manufactured by Shenzhen in China and appears different to others.

http://images.people.overclockers.ru/205524.jpg
http://cdn.head-fi.org/c/cd/cdd2b519_PCB_Compare.png
 
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Offline LucasArg

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Re: EEVblog #596 - World's Cheapest Soldering Station - Yihua 936
« Reply #141 on: May 08, 2019, 04:37:57 am »
LucasArg...
These two links are not working.
There is many different board layouts for the imitation 936 boards.
Mine is manufactured by Shenzhen in China and appears different to others.

http://images.people.overclockers.ru/205524.jpg
http://cdn.head-fi.org/c/cd/cdd2b519_PCB_Compare.png

Hello friend, if these links that you published do not work in other previous topics I think I have tried to see them. The cricuitos that I am seeing to make me a station is from hakko 936.
 

Online wasyoungonce

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Re: EEVblog #596 - World's Cheapest Soldering Station - Yihua 936
« Reply #142 on: May 08, 2019, 05:39:47 am »
Hi Lucas I sent you link to my files on google drive.  I think ZD1 is incorrect on most "Web" images.  I sent you eagle PCB files and pdf on correct layout.

This is an old design, works ok, maybe there are newer better designs out there.  That said I like the "analogue knob".   Buying a pre-made PCB or kit from fleabay would be cheaper.  But most 936 PCBs are poor copies missing many parts. 
I'd forget my Head if it wasn't screwed on!
 
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Offline LucasArg

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Re: EEVblog #596 - World's Cheapest Soldering Station - Yihua 936
« Reply #143 on: May 08, 2019, 05:57:20 am »
Hi Lucas I sent you link to my files on google drive.  I think ZD1 is incorrect on most "Web" images.  I sent you eagle PCB files and pdf on correct layout.

This is an old design, works ok, maybe there are newer better designs out there.  That said I like the "analogue knob".   Buying a pre-made PCB or kit from fleabay would be cheaper.  But most 936 PCBs are poor copies missing many parts.

Thank you very much friend. Now I hope to have my station thanks to you because in Argentina they are somewhat expensive for me and bringing from outside is complicated. Any question I will be communicating with you.
 

Offline nickeevblog10

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Re: EEVblog #596 - World's Cheapest Soldering Station - Yihua 936
« Reply #144 on: May 08, 2019, 06:44:19 am »
What do you think is the problem when I press the heatsink on the Mosfet the LED goes off and will only come on when I turn the knob higher then lower back and forth.
I am not so interested in this not.
I might buy a board and a 5 pin soldering iron for this Shenzhen Atten 936b, I can not find a 7 pin replacement board for a seven pin solder iron.
 Thank you.
 

Offline nickeevblog10

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Re: EEVblog #596 - World's Cheapest Soldering Station - Yihua 936
« Reply #145 on: May 08, 2019, 07:07:14 am »
I found on the schematic 26 MAR 2011 v1.7 PC BOARD AS VIEWED FROM THE COMPONENT SIDE ZD2 position seen to left of PVR temp Control is from top to bottom Z D 2. So writing on schematic for ZD2 is top to bottom on schematic picture.
 

Offline Feliciano

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Re: EEVblog #596 - World's Cheapest Soldering Station - Yihua 936
« Reply #146 on: June 08, 2019, 04:51:29 pm »
FWIW: Another version of the 1IC controller board (not as nasty as the Dave's). Careful with the potentiometer, for the reviews I read it's very flimsy.
« Last Edit: June 08, 2019, 05:03:07 pm by Feliciano »
 

Offline Feliciano

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Re: EEVblog #596 - World's Cheapest Soldering Station - Yihua 936
« Reply #147 on: July 07, 2019, 02:45:22 pm »
BTW, previously in this thread it was mentioned:
There are multiple variations of this thing:
936 - 35W analog (30€)
936A - 60W analog (80€)
937 - 50W digital with dial (55€)
937+ - 50W digital with buttons (60€)
950 - 60W SMD tweezer handle (60€)
3210 - 70W, digital (70€)

But I'm curious about the other models: does anyone knows the alleged difference between: those and 936a+, 936b, 936e? (Some 936d/937d has a digital display, some 936d has an USB port).
« Last Edit: July 10, 2019, 09:31:56 pm by Feliciano »
 


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