My station iron / hot air "Explosed" Ref JCD 8898

[GGMM]

Hello,
For several days I have been doing tests to desolder sotp  54 legs circuits with my hot air station and welding JCD 8898.
I had already had a problem with the iron that no longer worked and had found the solution on you tube. A 5v zener to change.
There, really bad luck, the station "exploded".
Fuse blown and component damage inside.
A reference cannot be read on a IC component , the blue component blacked out, I don’t know what it is, can be a high voltage capacitor.
In short, fortunately the old soldering iron will be used to help the new one.

Question: Do you have the schematic  and / or this pcb is in spare part in case?
Surely the main capacitor must be in the  short  circuit. To see
Thank you for your help.
cdt

[GGMM]

hihi,

Same case here.
https://www.eevblog.com/forum/beginners/alternative-ic/

Now schematic to find.
cdt

[R-1125F]

Could it be a DK125 as it said in the other post? 
The datasheet has a schematic for a typical circuit.  See if it matches the circuit in your unit.

Link  to datasheet.
https://datasheet.lcsc.com/lcsc/2111241030_Shenzhen-DongKe-Semicon-DK125_C171868.pdf

[GGMM]

Thank you for your answer

Yes the destroyed main circuit is a DK125.
All primary circuitry is out of service.
The MB6S bridge is short circuit, the 10µF 400v looks good but it will be replaced, the varistor 10471K is infinite, so to replace also, and for safety I will also order triacs BTA16.
In addition a track in the primary has melted (Track of barely 1cm, so repairable).
I think that simply the case did not like to be connected with iron and hot air connected to ON at the same time hence a large current call. A little of my fault.
Now go to A.....X to order.

[wraper]

the 10µF 400v looks good but it will be replaced, the varistor 10471K is infinite, so to replace also

Cap has nothing to do with the fault and varistor must measure open circuit unless it's faulty. They don't even fail open unless break in half. IMHO IC failed short and subsequently took out rectifier by overcurrent.

[GGMM]

Hello,

In principle you are right.
Being on site and for a few more euros, I prefer to order the active components (some are not on E...Y), at least I will have spare parts and this will avoid waiting 3 weeks for delivery.
For 4 euros more, I ordered also  2 curved nozzles, it will be easier to desolder.

Another question, do you have a site that references all models of nozzles, especially for SOT circuits. I did not find.
ex models 1131.1132,1133...etc is not relevant for dimensions.  (4.8*10mm, 5.6/13mm, 7.5*15mm,...)
cdt

[GGMM]

Hello,

While i was looking videos on the JCD 8898..
For those who did not know (like me), there is a temperature calibration function for the soldering iron. But you have to have a suitable termometer.
Also comments on the DK125 destruction...


cdt

[GGMM]

Hello,

I received the memories for my Yokogawa dl1640 oscilloscope acquisition card.
I couldn’t change them right away because my hot air station is down (waiting for components).
I wanted to know if anyone has ever experienced this technique of passing a copper wire between the legs of the IC to be unsoldered to lever and lift it.
Then it remains to heat on the other side and recover the circuit.
It seems to me more effective than using a pliers that can slide and scratch the tracks.
See example an old ram.
cdt

[mariush]

How is it any different than just adding solder and bridging all pins on one side with solder? 
Or get some copper wire (for example from ethernet cable) and lay it across the pins and add solder.

Pretty much same thing.

[GGMM]

Mariush,

The wire comes from a former transformer of a radio transistor.
It must be thin enough to pass between the legs.
Heat in a classic way with the hot air station and pull the wire gently to take off all the legs. Just heat the other side to remove it completely.
The advantage is to heat one side at a time. It’s a technique like any other.

cdt

[GGMM]

Hello,

I received today the components to repair my hot air station JCD 8898
So I changed the input varistor (A case where), the diode bridge MB6S (was short circuit), the circuit DK125 (destroyed), the triac BTA600B and the fuse.  Nb Capacitor 100µF 400v is good.
Surprised for the fuse because it looks like a 6A 250v?? Unless it’s a 600ma (?)
Anyway, I put a 2A to see.
Before starting, I would like to point out that the soldering iron and hot air are not connected.
Power on with 2 switches off. Nothing (normal)
Turning on the iron part, the display lights up with the old temperature and you can adjust with the + / -keys. (So the +5v is supplied by the regulator, itself powered by the cutting part power)
Turning on hot air...and then it all blows up.
This looks less violent, but the fuse is blown and the diode bridge is again out of service.
The DK125 seems intact and  no short circuit on it
In short, there must be something left to change on the power board.
If someone had the same case and especially if you have the electrical schematic.
Thank you

[GGMM]

The 2 components not changed are:
FL817B. 4 pins photocoupler (For the power). So i think it's good

The EL3041. device each consist of a GaAs infrared light emitting diode optically coupled to a monolithic zero voltage silicon crossing photo triac.
They are designed for use with a discrete power triac in the interface of logic systems to equipment powered from 110 to 380 VAC lines, such as semiconductor relays, industrial controls, engines, solenoids and consumer appliances.

To be tested surely?
cdt

[mariush]

Use an incandescent light bulb in series with your AC to prevent parts from blowing.

You now know the heater parts causes problems, so I'd start by actually checking the heater element maybe it's cracked or broken in some way that causes shorts.
Use a multimeter in continuity mode to see if some parts are shorted or going to ground which could cause the bridge rectifier to break

The optocoupler + triac are basically like a mechanical relay, turning on and off to send power to the heating element or not, but they're clever enough to turn on or off at a zero crossing or very close to that.

You can see in the video below how to build a current limiter...  note it has to be incandescent (classic) light bulbs, not compact fluorescent bulbs, not led bulbs... the filament of the bulb has to act as a resistance and limit the current.

[GGMM]

Hello,

Here’s the station is now OK
After another disassembly, a wire seemed to come out of the hot air outlet.
Everything went back to normal after we got it back together.
I confirm that a strong enough fuse (6A) is required, as there is a large current demand when the soldering iron or hot air station is switched on at the start. A smaller one blow.
cdt

NB:  now I will be able to take care of the memory's of the DSO DL1640 Yokogawa. (see post) New adventures. LOL

[yfayula]

I would agree that it is a switching regulator. The blown up cap is part of the primary side of the switching tranformer filtering circuit. Guessing the value on it shouldn't be a big deal.

[GGMM]

Hello Yfayula,


The primary main capacitor is a 100µF 400V. It has not been changed because I did not receive it in time and is in good condition.
The problem was on a short circuit hot air connection wire. This blew up the small rectifier bridge and the MK125.
It’s changed and OK.

Now I want to tackle the memory of the oscilloscope DL1640.
However, it is impossible to remove a first memory chip in hot air. I put some flow, heat and even try hard (450 C), it doesn’t melt while I did tests on a memory strip without any worries.
I am considering two solutions:
1st) Grind a pliers to cut the CI legs as thin as possible to pass between the legs and cut them. (5 pliers for 12€ on A...N  to try)
2eme) solder a string of old PC  on the legs of a memory and see the signals on my oscilloscope (Adress, data, etc.)
The addresses are common to all 4 memories, only the data do not seem interconnected. (Test with multimeter)
Advantage: Avoid unsoldering "good" circuits and possibly find the bad chip.
I don’t want to heat up by spreading solder on all the legs.

cdt

[Tozsa Attila]

Hí. My problem is that the temperature display of the soldering iron is dim and I cannot adjust it.  If I turn it on, the paka glows after 10 seconds