Aoyue 738 4 in 1 solder station power board

[mentholflash]

Hi all
Hope sumone can help.
the heating element failed, so i bought a new one researched how to replace it.
I wasn't looking forward to it much but was gonna do it anyway.
i powered it up just to make absolutely sure i needed to. (This was my first big mistake)i knew it needed changing.
so got all tools together, i started taking out screws and consentrating on instructions from the laptop.I grabbed the old element with a pair of pliers to pull nit out of the handle and bang little puff of smoke it was still plugged in.
so 20 years later can anyone help me diagnose and repair the power board just to see if i can get it up and running again.
Thanks in advance
Phil

[AndyBeez]

Have you checked the 20mm fuse on the back of the case? The original heating element would have been at mains voltage when you tried to pull it out, which shorted to ground.  So the fuse may have popped.  Otherwise, something else such as a semiconductor failed. So unless you are willing to check each component, then perhaps you can put this down to experience and just salvage the parts?

[mentholflash]

Hi mate
Thanks for the reply the fuse is intact?
and yes will be happy to measure all components just dont know what to look for i get ohm's reading on a lot of the board about .56ohms
thanks for ya hep so far mate
cheers

[mentholflash]

Hey mate on your avatar it says you are from christmas island?
is that true
cheers

[AndyBeez]

My thoughts if the fuse is ok, suspect the Triacs or their controlling opto isolators.

Hey mate on your avatar it says you are from christmas island?
is that true
cheers

Actually, UK based but as we say here, every day is Christmas.

This is because we have a political class who treat every day as if it were a P _A R T ^A Y

But this outside of the vectorscope that is the EEVBlog.

[mentholflash]

Ahh Yes
Not sorry i left to Sunny Western Australia
The ba12 -600b in resistence mode pin 1 to 2 o.l
pin 1 to 3 .028 beep

ohms 1 to 2 o.l pin 1 to 3 43.9ohms
That is the 1 behind the 4 pin header nxt to blow resistor
Also not sure what a opto isolators is
Cheers for your help mate

[eurgenca]

1. Replace R1
2. If no heating or you have a constant heating replace triac BTA12-600.

[mentholflash]

Ok
I have a new problem the board is powered but no display and no heat
But its on and trying
can anyone help further
Thanks

[wraper]

1. Replace R1
2. If no heating or you have a constant heating replace triac BTA12-600.

I rather suggest checking if triac is shorted before powering anything. Running with shorted triac can easily destroy new heating element in a few seconds, especially when air pump is not running.

[wraper]

Ok
I have a new problem the board is powered but no display and no heat
But its on and trying
can anyone help further
Thanks

Low voltage part of circuit is powered from transformer. It could be you did not connect it to the board properly. There are 3 identical 4 pin connectors which you could have mixed up. You need to be very cautious about connecting those as one of them is connected to mains voltage (provides power to either hot air heater or air pump). Mixing up can easily destroy things or even cause electrocution.

[mentholflash]

Thanks for your input mate
There are 3 triacs and 1 regulator from what i can work out    But i'm the idiot who did it in the first place So;;
tested triac but only have a fluke 73 so only checked for shorts in circuit.
No shorts pin 1-2

The ba12 -600b in resistence mode pin 1 to 2 o.l
pin 1 to 3 .028 beep
ohms 1 to 2 o.l pin 1 to 3 43.9ohms

wires would only just reach

Any idea where to go nxt
Cheers

[AndyBeez]

It looks like those connectors will just find their way home into the right pin header. Next, methodically test the power rails and check the voltages. I suspect from your first photo there is just one rail providing five volts to that big fat Atmel microcontroller.

Beware, the board could be LIVE when connected, so please wear rubber or latex gloves when probing. And make sure you test relative to circuit ground and not mains NEUTRAL which may have also been traced somewhere on that board. The bare metal heatsinks on the Triacs could also be at mains voltage.

Without a circuit diagram, fault finding can be a best guess, based on experience and electric shocks 

The opto-isolator is the white chip - which switches the high voltage Triac using a low voltage GPIO pin . There are possibly two others which are the black six pin chips. Opto-what? https://en.wikipedia.org/wiki/Opto-isolator

[wraper]

The opto-isolator is the white chip - which switches the high voltage Triac using a low voltage GPIO pin . There are possibly two others which are the black six pin chips. Opto-what? https://en.wikipedia.org/wiki/Opto-isolator

White optotriac is for 24V soldering iron. 230V heater and pump circuits have black optotriacs.

[mentholflash]

Hi all
Pump runs as soon as extraction or hot air is turned on but no heat
as to the optotriac i tested for shorts pi 1 and 2 on all 3 but in circuit
Do i need to remove them
i was probably going to try triacs next but can only get 1 sort bt137600e in my town
cheers guys

[AndyBeez]

White optotriac is for 24V soldering iron. 230V heater and pump circuits have black optotriacs.

So what are those two tracks running under the opto isolators doing there? I thought isolation was a physical layout thing too?

@mentholflash: Maybe post a photo of the underside of the PCB?

[wraper]

White optotriac is for 24V soldering iron. 230V heater and pump circuits have black optotriacs.

So what are those two tracks running under the opto isolators doing there? I thought isolation was a physical layout thing too?

@mentholflash: Maybe post a photo of the underside of the PCB?

It's a poor layout which is not surprising as Aoyoe is a low quality Chinese garbage. Not that much better than Yihua, just have been way longer on the market. As station is grounded, creepage distance probably is barely above allowed safety minimum though. BTW creepage distance from white optotriac is about the same, it's just that closest trace is on the left side and resistor on the right side of it rather than trace running under.
EDIT: Also you can see that triac circuit with white optotriac is connected to the same connector as rectifier for low voltage power and the distance there is much lower.

[mentholflash]

The underside
Cheers

[mentholflash]

Hi all trying to test connector for front panel!
can anyone tell me where to put com lead from multimeter to measure front panel plug to test for 5v voltage
Thanks

[mentholflash]

I measured the voltage while powered from five pin header by the large Atmel from left hand pin of left hand resistor
from left to right on power board
1  2.129v
2 2.883v
3 2.137v
4 2.095v
5 2.047v

front pannel 5 pin header opposite right to left
1 2.128v
2 2.812v
3 2.133v
4 2.101v
5 2.099v

if any of that means anything
but it does mean theres power to the front board so why no disply
has the front board been hit too
Thanks all

[AndyBeez]

Thanks for the back side photo. Makes more sense when tracing the parts.

What is the component part number on the voltage regulator? The matching voltage should appear on the trace feeding out across the board.

There is also a big fat power diode 'F' next to that solder bridge/blob. Measure the DC voltage on both sides.

[mentholflash]

Would that be on the other heat sink
l7805cv cc02r vw mar 509
Cheers

[AndyBeez]

Would that be on the other heat sink
l7805cv cc02r vw mar 509
Cheers

That is the 5V linear regulator. Confirm you have 5 volts on the output side.

https://components101.com/ics/7805-voltage-regulator-ic-pinout-datasheet

[mentholflash]

hey mate
couldnt get in there when its inhouse so gonna solder a wire on the leg and try and reach heatsink with the meter pin

[u666sa]

There is not much to check and replace here. Besides the obvious big resistor, you have two areas looking crusty-ish.

Check all these small resistors.
D6 (or D5) looks bad.
20 years is time to take the caps off, and check the ESR. Replace all caps with same values bigger voltage, though make sure to check ESR.
Check and replace if needed all 4 heat sinked regulators.
Check and replace all 3, 8 leggies. You just pull up data sheep and see what voltages should be there.
Check and replace all 3, 6 leggies.
Make sure your oscillator is oscillating.

That's pretty much it.

If you not sure what to replace, replace everything. The only thing is to check that new caps are good. 


Look, on my 2703A+ there was an actual power board in the back and it had two fuses. The controller, here you have something that looks like a controller, that was in the front, was okey. Maybe you have another board in the back, to where power from transformer connects to. Look for board with two fuses on it. If the station shows 89C and temp is not rising, usually it's those fuses.

[mentholflash]

Hi all
Thanks for all your effort so far.
i started checking resistors and found the new 1 i put in now measurses short 0.029 continuous beep
and other 2 large resistors dont measure at all OL
also R3 reads 0.029 i read them all
R22 read at 2.006
1 at 1.639
5 at 1.132-1.234
The rest .279-.710
not sure what that means i am cosidering going to the local electronics shop and seeing if i can just re-populate but dont think theyll have everything and the 8 legg and 6leg ic's are missing identification
Thanks Again