Teardown and Reverse Engineer of Yihua 898D combination Hot air and Soldering station.

[@trutester]

Thanks so much for this video. I had something fly through my gun and after the awful fan noise I lost my heat. I want to upgrade my gun with the removable plug. With your work on this I can make sure I don't kill the whole unit with a mis-wire. Thanks again!

[@patrickmontier6851]

Hello thank you for this great video. Bonjour merci pour cette excellent vidéo.

[@wallybe2946]

Awesome very informative Thank-you for your time and effort

[@franciscofortunato1864]

Interesantísimo trabajo! Gracias!

[@HappyPlaceBlog]

Thanks for your efforts on all this.

[@ozcanaltinbas3101]

Thanks for this great video.

[@uhmgawa1435]

I have one quite similar likely having exited the same Shenzhen factory strategically located within rickshaw distance of a shipping port. Most of these older designs have that 50/60Hz copper/iron anchor for 24VAC power of the iron heater. Looks like that has recently been punted with newer designs using an "almost enough" 24VDC switcher and a low side mosfet to PWM the iron heater. That 24VDC is convenient also for powering the hot air blower. For some reason the goofy power darlington speed control design still persists. I'd have expected to now find a PNP bipolar in a bare bones buck circuit PWM'ed from the uC to control the blower speed. Then drop the analog pot for a center-push rotary encoder to address all functions via that vs. the clumsy tact switches. The thermocouple "instrumentation amplifiers" with a LM358 are another opportunity for screaming into a pillow. But they've got an input voltage offset null in there so no problem! The mains transformer design did have one numb benefit in that it could bring up the iron heater from a cold resistance start by sustaining the brief 3~4x current overload which the barely passable switcher won't do unless the firmware does a controlled soft start to prevent SMPS from entering OC shutdown. I'd realized this during a boneyard engineering exercise using a cast off laptop 90W adapter and boost converter (19 -> 24V) where that combo could more than sustain the current required for any practical working temp. But the SMPS would shut down unless I ramped the heater from a lower voltage (or PWM) soft start. Happy Hacking.

[@jaym5938]

Good explanation. My hot air indicator stops at about 350c and won't go higher (rated to 480c?) Can't figure out why. Sometimes the soldering iron goes supernova, too.

[@boonedockjourneyman7979]

Your stuff is good. Please do more.

[@Datzfunk]

Thanks!

[@Scyth3934]

Well done!

[@Fortatus]

Hey, great work. Thank you. Can you please tell in more detail when you bought your device? What's interesting to me is, that R4 is missing on your board. That 120k resistor would connect to mains and blew in different Yihua devices a few years ago. (There are several videos on youtube that show this resistor burnt out or darkened as it is overloaded) Now I've seen two videos of newer devices that are missing this resistor. So, did you remove that resistor or was it missing from the start? Would be interesting to narrow the timeframe down when Yihua began to leave that part out.

[@Datzfunk]

Hi Fortatus. No, I did not remove any resistors, all that you see here is stock. R4 was never populated. According to Amazon I bought it on April 2, 2016. Thanks for the input!

[@hoangtung-ok8px]

hello, my 898d soldering doesn't show the electronic board, it only has wind from and no heat when it turn on, don't know if you have any suggestions for me, thank you!

[@leopaulevans7573]

my 878d the soldering gun is getting hot but not the hot air gun i replace the heat element that came in the box still no result am get the H-E error message i also check for continuity from main board to the handle and its all ok any advice

[@Datzfunk]

The main things involved with the hot air are the heating element and fan, the thermocouple and amplifier for it, and the microcontroller switching the triac circuit on and off. I would make sure your heating element/fan/thermocouple connections are all good in the handle and on the board. Then you can look into the more complicated things like the thermocouple amplifier, and the circuit that drives the triac.

[@leopaulevans7573]

@@Datzfunk and have to replace the original triac BTA12-600B because the diode voltage drop was a bit low when I testing it in the board and when I was removing it from the board one of the pin got damaged so I replace it with this BTB25-600B from the electronic store which this the difference the ampere rating , and am also getting 110v on the lead wire that goes to the handle some and thinking its a problem with heat sensor thermocouple circuit

[@Datzfunk]

@@leopaulevans7573 It could be. Check to see if there is a signal coming from the microcontroller to drive the triac. If there is not, it could be a problem with the thermocouple.

[@nilolee2426]

I bought a sumsour station in Amazon and it’s working fine but there’s no transformer! I’m not sure if they are reliable without it, any idea?

[@Datzfunk]

That's interesting. Is it just a hot air station by chance? Perhaps they're using a switch mode power supply instead.

[@nilolee2426]

@@Datzfunk it has both air and soldering iron, I posted 2 videos under my name and the title is sumsour 8586 solderin station

[@CadilloBejar]

Do you know where I can see the diagram of the SAIKE 898D heat station?

[@michaelperez7121]

the zener (original is C8V2 8.2 VOLTS) control fan. you use IN4148 NOT PROBLEM? USING IN4148?? 100V ZENER?

[@SerenoOunce]

Did your unit come with the main toggle switch on the back? I had to install one myself on mine. My unit had the hole for it but was covered by a sticker. A failed TRIAC does seem to be a common problem. After replacing mine several years back I put on a larger heatsink and been working fine since. Though did also have to replace the heater element and reed switch. Considering the use and abuse it gets I'd consider that std maint though.

[@Datzfunk]

Yep, my unit came with the a power switch on the back. That's odd about the sticker, maybe they were trying to cut costs? Interesting about the failed TRIAC and the larger heatsink, I'll keep that in mind if mine ever fails. Thanks!

[@thewanderer1726]

I have a 898D and the iron triac driver is a 2N3904. The PCB print shows that too. In your schematic, you say that is a 2N3906. Could you confirm?

[@michaelperez7121]

es un 2N3904 y lo consigues facil cualquier trassistor npn le hace 2n4401 es el mas vendido en steren y es igual

[@DSD-u2m]

Nice video 👍🏽

[@JYajure]

how much is the Voltage of the zener diode in Hot Air Fan Control? Thnx

[@WESK18]

I broke mine I forgot to turn it off and was soldering some wires for a connector mod, it's displaying 3 dashes and stays on 100c,no heat no fan blowing, checked triac it was shorted I replaced it, no change replaced moc ic, no change checked the rest of the components they seem fine but can't figure it out (noob)

[@trocandoconhecimentos7101]

VERY TKS!! ONE MORE SUBSCRIBED!!

[@dsd2918]

All small resistors in this are 1/8watts. Can I change it to 1/4watts with the same value? Please reply and help me.

[@Datzfunk]

yes, you can always substitute a resistor with a greater power rating in place of one with a smaller rating so long as they are the same type.( Don''t substitute a wirewound for a carbon film unless you know it is ok in the circuit)

[@dsd2918]

@@Datzfunk Thank you for your fast and kind reply. I will change only 1/8watts resistors with quarter watts. I think all those are carbon resistors. I will reply soon.

[@dsd2918]

​​@@Datzfunk I changed all major big components except resistors, MOC3041, micro controller and display IC. when I turned on I was not able to reduce the temperature of both. The temperature was stuck on 400 and fried my hot gun. It was molten red. Its plastic body also melted. Should I change MOC3041 IC? Resistors are still 1/8watts and tested, all are good. Any solution?

[@gc9n]

Problem : Hot air not working , cool air comming only. Solutions: chaneged element didnt work, changed the MOC4031 the element was on fire didnt stop . changed the BTA16 , nothing worked , HOW can i check Air_Triac_Driver if its pushing data?

[@DSD-u2m]

I have the same and using it from 2 years. But now the soldering iron is not heating properly, like intermittent heating. Moreover I have checked it with 2 soldering irons. But the problem still exists. I am confused whats the problem. Can you give me any idea? 🙏🙏🙏

[@Datzfunk]

Intermittent problems are difficult to troubleshoot. The easiest thing you can do is to check for connectivity issues, like the one I had. Cracked solder joints and bad connections can cause intermittent issues.

[@DSD-u2m]

@@Datzfunk I will try it and let you know 👍🏽

[@wepipe]

SO!!! Wirh an intermittent fault == 'tap-test' all 'board-external connections' for its detection, followed by same at the board, prior to checking board-components electronic characteristics. RIGHT ! Derrrrrrrrrrrrrrrrrr