EEVblog #596 - World's Cheapest Soldering Station - Yihua 936

[Jason114]

I have the Atten 937b iron, very similar to this for home use. With $3 clone tips off eBay.

It is a nice iron for the price, obviously not a JBC (which I use at work), but gets the job done. I have soldered 0402 components as well as 2.5mm^2 wire and it does OK.

What do you expect for $20? It serves its purpose for me. If ever I have £200 "spare" for just soldering a few components a month, I'll buy a JBC or Pace iron for at home. In my dreams!!

I have a Atten soldering station as well. It is low priced and with good quality. For cheap soldering stations, you can choose Yihua, Atten, Aoyue.

[miguelvp]

So I got the hakko 908-CK conversion kit and it fits my clone, it came with:

1 - 900L-T-3.2D Large Mass Tip
1 - B1787 Enclosure
1 - B1794 Enclosure Nut
1 - B2033 Nipple

Changing the iron from a 907 medium iron to a 908 large iron. I also got an extra 5 900L-T-3.2D tips from tequipment.net. I would have bought the conversion kit from them but they don't have it anymore.



Here is the 908-CK fitted and below the 907 clone.

[AndersAnd]

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.

[amyk]

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.

[han]

buying one

[wasyoungonce]

Hi Folks..I purchased a Hobby King Yihua 936, obviously there are faults that most are fixed, but, looking at the transformer, there is no way it's more than 35~40VA.

My question, I am using this as a 2nd station and building a complete DIY 936 clone OEM PCB circuit and non OEM parts etc.  I need suitable transformers, for these units.  I read the 936 is ~ 60VA transformer, I can find a 50VA to fit the transformer mount posts (of the case) but suggest a 73~75VA unit (or even a 100VA) would be more suited.

Has anyone built or modified such a unit and what transformer did you use?  So far I have searched RS/Element14/fleabay/Jaycar/Altronics (Australian user) and found some but they won't fit the case mounts.  I wanted these units for easy stacking, I need dual irons and there are plenty of cheap parts available (yes I know non original).  I am retiring my home made dual iron Adcola/Royel Hybrid system I built back in the 80's as it is just too low in wattage.   Yes I have other higher wattage irons (non temp control) but wanted a controllable station on the cheap with dual irons.

I'm a cheap arsed but know the need to pay for a decent iron/tips/controller PCB and transformer so any advice welcomed (even considering buying a proper Hakko 907M iron, full price, but where?).

[wasyoungonce]

Ok purchased an original C1143 iron, Hakko 907, from RS components, plus some OEM tips, but noted the iron or packing does not state "ESD safe".  Looking at the iron, its definitely Hakko but was wondering...is this iron indeed for their 936ESD stations or is it one of their older white version versions?  The iron is white!

Also I'm assuming the Hakko 936 station is a 50VA transformer?

Anyone!

[bosondehiggs]

Hello my yihua 936 burn today (connector shortcut)

Can someone tell me value for R1,R2 and fuse?

Thanks

[bosondehiggs]

thank you!
any idea for fuse?

[wasyoungonce]

Ok checked mine be careful there are probably many variants of this PCB out there.  Mine is marked YH 936AV10-3^IQ   

R1 is 330 ohm; R2 is 150 ohm; fuse is 1Amp.

I'm changing my PCB/Transformer to OEM copy (and 75VA transformer) as the std ver is ok heating a pencil tip but struggles badly with a 3.2 chisel tip.  Also I have an OEM 907 iron and 907 clone (with same heater/PTC heater feedback) so commonality of changing irons is important to me.  The Yihua iron uses a thermocouple feedback and is probably around 35~40W iron heat max (at best)!

I'd suggest if your resistors went then you have another issue that caused this.....looking for a cct to help in this atm for you.

edit:
ok looking at PCB...looks as if they come from 24V in/triac and looks as if your triac is probably bad, also check D1!

[bosondehiggs]

thank you .

I have same pcb, i need to buy fuse for test.
I check D1 look good.

[wasyoungonce]

Forgot to say, fuse is 1A for 240V, 2A for 110V!

Don't know which version power input you have so check this,

[wasyoungonce]

Finally....

Ok made some Hakko OEM copy PCBs and ordered a front panel and new case from fleabay as well as a host of parts, including new transformers. I now have a 936 station OEM copy ( although I'm using a 75VA 24V 2ndry transformer) and an original 907 iron (from RS) including a handful of OEM Hakko tips. Also changed the main power switch to a neon type and put in proper M205 cartridge fuses on this main switch, with a new sub PCB for this. Also put M205 cartridge fuse on the main PCB for 24V (transformer secondary) pwr to PCB.  Cannot think for the life of me why Hakko didn't originally do this.

Also doing the "on power LED mod".  Forgive my photographic skills!

This new system heats much much faster than the Yihua (25~30 secs or less with 3.2mm chisel tip) and has no problems doing big tasks and has much better thermal stability. Pretty much because the Yihua transformer was ~35VA! The Yihua heater tip is a nichrome wire in a ceramic tube and the ceramic end cracked on mine and is showing nichrome heater wire...barely ~1mm away from the tip metal (ground). Not good.

Also I found the Yihua uses a non std thermocouple temp feedback (mentioned before by others) which is not the same as the Hakko 907 iron PTC feedback. Funny enough I found a place in Aust selling very good copies of the 907 iron with the same ceramic heater and PTC feedback as the Hakko for ~$20, not bad indeed! Now I can change irons and keep calibration, I've ordered a thermocouple tip temp calibrator),

Just doing the 2nd station now but using a 50VA transformer for the 2nd one.

One for the safety inspectors.....  my Yihua soldering station they wired the active/neutral wrong and switch/fused the wrong line. The Active (Line) was the blue wire, the Neutral (N) was the brown wire (it should be the other way round the moulded plug is made/wired wrong). The main switch also switched and fused this brown (Neutral) wire. At least the earth was correct! Safety standards......Ahhh yes China has a long way to go!

[Fungus]

One for the safety inspectors.....  my Yihua soldering station they wired the active/neutral wrong and switch/fused the wrong line. The Active (Line) was the blue wire, the Neutral (N) was the brown wire (it should be the other way round the moulded plug is made/wired wrong). The main switch also switched and fused this brown (Neutral) wire. At least the earth was correct! Safety standards......Ahhh yes China has a long way to go!

Electric current goes down both those wires with equal intensity.

(And large areas of the world have plugs that can be inserted either way around...)

[wasyoungonce]

Electric current goes down both those wires with equal intensity.
(And large areas of the world have plugs that can be inserted either way around...)

Quite cognisant with what electrical current flows in must flow out.  The Australian 230V type power plug, is unique to a small number of countries, Australia, New Zealand, Argentina, ...China is similar in some areas.  This plug cannot be "inserted the other way round".   They all use the same colour codes (that I know of) and switch (or should switch) active or line "brown".
http://www.openelectrical.org/wiki/index.php?title=Cable_Colour_Code

Of course, with 900+ posts, you would be very aware that not switching active allows electrical charge to be present thru the transformer primary and to the switch at all times, even when the station is switched off (but still plugged in to an "on"power point).   One can forgive some small electrical faux pas from China ....like lack of star washers on transformer ground but to mould the plug wrong colour code is an electrical cardinal sin for obvious reasons.

Just trying to put this out so others are aware of this hazard.

[Monkeh]

Would you care to elaborate on where, exactly, the hazard of incorrect polarity in functional switching for a double-insulated device arises?

[wasyoungonce]

Would you care to elaborate on where, exactly, the hazard of incorrect polarity in functional switching for a double-insulated device arises?

Yep, an over-voltage or lightening strike on power line (happens a lot in some tropical areas), primary of transformer is still live (because it hasn't been switched off), shorts to earth (arc over)...the rest is obvious.  Yes, this should activate house RCDs (if fitted, RCDs are fitted by Australian standards in homes since ~ yr 1998'ish), yes its double insulated but the hazard is with the primary not being switched off.

Its really poor practice not to switch the active, in fact dangerous.  Especially if someone is poking around inside the unit thinking it's switched off.  Oh I should also say that this device is not really a double insulated device by definition.
https://en.wikipedia.org/wiki/Appliance_classes

I changed my switch to an SS21 double pole single throw (neon) as someone else did in this thread.  But that was for visual purposes.

edit:

ahh looks as if the Argentine electrical plug is wired opposite to the Australian  ..quote wiki ..."The most important difference from the Australian plug is that the Argentinean plug is wired with the line and neutral contacts reversed."
https://en.wikipedia.org/wiki/AC_power_plugs_and_sockets
Now there's your problem...Argentine/Australia...all very similar spelling!

[Fungus]

(large areas of the world have plugs that can be inserted either way around...)

The Australian 230V type power plug, is unique to a small number of countries, Australia, New Zealand, Argentina, ...China is similar in some areas.  This plug cannot be "inserted the other way round".

So... all those other countries are living in constant mortal danger. Got it! 

[HighVoltage]

Germany has pretty safe plugs but they can be inserted either way around and we do not have a problem because of this.

[Monkeh]

Would you care to elaborate on where, exactly, the hazard of incorrect polarity in functional switching for a double-insulated device arises?

Yep, an over-voltage or lightening strike on power line (happens a lot in some tropical areas), primary of transformer is still live (because it hasn't been switched off), shorts to earth (arc over)...the rest is obvious.  Yes, this should activate house RCDs (if fitted, RCDs are fitted by Australian standards in homes since ~ yr 1998'ish), yes its double insulated but the hazard is with the primary not being switched off.

Sorry, but again, this is functional switching, not isolation, and in many cases polarity is not ensured. It is nowhere near as big a deal as you make it out to be.

[wasyoungonce]

It's only a problem in that as stated if someone opens the unit and is working on it expecting the Active to be off...!  But in respect to switching active, 230V is a lot more electrical shock dangerous than 110V.  Body resistance decreases with increasing voltage and increasing voltage increases current flow thru the body...maybe because, this is why the active must be switch in Australia. 

I really cannot comment on other world systems and their regs.   But for Australia, this product would be banned if known...this is why I raised this.

[Monkeh]

It's only a problem in that as stated if someone opens the unit and is working on it expecting the Active to be off...!

Do I need to elaborate on functional switching vs isolation?

But in respect to switching active, 230V is a lot more electrical shock dangerous than 110V.  Body resistance decreases with increasing voltage and increasing voltage increases current flow thru the body...maybe because, this is why the active must be switch in Australia. 

I really cannot comment on other world systems and their regs.   But for Australia, this product would be banned if known...this is why I raised this.

The active must be switched in Australia (and the UK) only because we have the luxury of the reasonable assumption of specific polarity.

[wasyoungonce]

It's only a problem in that as stated if someone opens the unit and is working on it expecting the Active to be off...!

Do I need to elaborate on functional switching vs isolation?

But in respect to switching active, 230V is a lot more electrical shock dangerous than 110V.  Body resistance decreases with increasing voltage and increasing voltage increases current flow thru the body...maybe because, this is why the active must be switch in Australia. 

I really cannot comment on other world systems and their regs.   But for Australia, this product would be banned if known...this is why I raised this.

The active must be switched in Australia (and the UK) only because we have the luxury of the reasonable assumption of specific polarity.

Well is the item intrinsically safe?  No because potential is present in the primary of the transformer at all times unless off at the power point. 

When the assumption of specific polarity switching is found to be wrong, then pretty much IMHO it's worth mentioning.  Well I thought so.  So we have to disagree on these but understand each other perspective.

[Fungus]

Well is the item intrinsically safe?  No because potential is present in the primary of the transformer at all times unless off at the power point. 

That's true but it seems like a very minor safety problem to me.

You could also point out that the wire inside the power cable is still live

(Unless you're British, in which case there's a fuse inside the plug to disconnect it! Why don't you move over there, just in case?)

[wasyoungonce]

You could also point out that the wire inside the power cable is still live

(Unless you're British, in which case there's a fuse inside the plug to disconnect it! Why don't you move over there, just in case?)

Ha move to England....my Ancestors were sent out here from England...I don't think they want us back!

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.