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

[stj]

Re: Aoyue 738 4 in 1 solder station power board

start by explaining which connectors are for the element and the power input.
did somebody take a grinder to the chip numbers or is that paint?

[redwire]

Re: Aoyue 738 4 in 1 solder station power board

All I can see is the big power resistor (PC board silk says 1.2Ω) looks cracked and blown out. It must have acted as the fuse, although what happened to the unit's main fuse? assuming it has one. It must have been a scary experience.
This would coincide with shorting out the heater when power was on.
Check the resistor is not open-circuit.

I think the high-tech in this product must be secured for the People by sanding off the IC markings

cross-posted at https://www.eevblog.com/forum/repair...n-power-board/

[mentholflash]

Re: Aoyue 738 4 in 1 solder station power board

start by explaining which connectors are for the element and the power input.
did somebody take a grinder to the chip numbers or is that paint?[/QUOTE]

Hi mate thanks for the reply yes somebody took a grinder to the ic's on the power board but not on the other board.Dont know why?
The main fuse is untouched.
I did post on another forum i am a member of.
just hoping somebody can tell me what to measure and what that means and hoping it hasn't touched the other board.
thanks for your help so far guys.

[mentholflash]

Re: Aoyue 738 4 in 1 solder station power board

All I can see is the big power resistor (PC board silk says 1.2Ω) looks cracked and blown out. It must have acted as the fuse, although what happened to the unit's main fuse? assuming it has one. It must have been a scary experience.
This would coincide with shorting out the heater when power was on.
Check the resistor is not open-circuit.

I think the high-tech in this product must be secured for the People by sanding off the IC markings

cross-posted at https://www.eevblog.com/forum/repair...n-power-board/

Hi mate
do you know what wattage that ressistor will be to add to my shopping list
And yes was very scary
shat myself
the bang seemed to happen in my hands and the smoke came from the unit utter confusion
haha

[stj]

Re: Aoyue 738 4 in 1 solder station power board

which element was it, the iron or the air?

[mentholflash]

Re: Aoyue 738 4 in 1 solder station power board

Hot air
cheers

[stj]

Re: Aoyue 738 4 in 1 solder station power board

good - that simplifies it greatly.
the hot air is mains powered through a triac - see if you can find a triac on a heatsink.
part number is probably starting with "BT"
i would expect it to be close to the mains and output connectors.

[stj]

Re: Aoyue 738 4 in 1 solder station power board

here's a couple of schematics from similar devices to give you a starting reference.

as you can see, i like to archive tool schematics!

[redwire]

Re: Aoyue 738 4 in 1 solder station power board

That resistor (size 26x8mm?) is looking like 5W Metal Oxide, a chinese special - uncommon because you would find wirewound, ceramic at that power or higher. It might even be 6-7W, basically the largest they could stuff in there.
If it's got 3A flowing through it, that's still almost 11W so I'm not sure why they even have it in series with the heater. Seems odd.

Possibly connects to the triac near it, in the corner. I would check if it shorted which would cause the new heater to be full on and cause a meltdown.
Check ohms/diode-test MT1 and MT2 pins.

[mentholflash]

Re: Aoyue 738 4 in 1 solder station power board

Hi
Thanks so much for all the help
redwire what do you think i should replace the resistor with?
And do i need to remove from the circuit to test
it is a ST bta12600b then c3 over left leg and 06 over right
I cut the resistor then read the triac and across outside pins it shows dead short
cant seem to get the screw out of it thou
Thanks again

[redwire]

Re: Aoyue 738 4 in 1 solder station power board

Test the BTA12-600B triac in-circuit is OK (with connectors off), check for a short across A1 and A2 pins. That is the most common way they fail.

The resistor what does it read with ohmmeter? You think it's 1.2Ω matching the PC board silkscreen? I still wonder what it's for lol.

Any 5-7W wirewound resistor will do. Keep the high-temp insulating sleeves.
It's what fits. Yageo KNP500 series or SQP500. Royal Ohm PRW05, KNP05 seems too small.
I don't know what distributors you have over the pond.

[mentholflash]

Re: Aoyue 738 4 in 1 solder station power board

Ok
The resistor gives no measurements
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
As to the resistor being there i think it shows great forsite to know that some idiot is gonna pull out a heating element while plugged in
as for the 1.2 it was suggested earlier
it could mean 1.2 jigawatts
so not sure but quite hard to get the right size and wattage
Cheers for your help

[mentholflash]

Re: Aoyue 738 4 in 1 solder station power board

Hi all
polished up the resistor it is infact 1.2Ω on the calculator
brown red gold gold
What would my alternatives be
cheers

[stj]

Re: Aoyue 738 4 in 1 solder station power board

how big is it in mm?

[mentholflash]

Re: Aoyue 738 4 in 1 solder station power board

Hi mate
It's 22x8 1.2ohm 5-7w
some of the ones i looked at were 50mm
cheers mate

[stj]

Re: Aoyue 738 4 in 1 solder station power board

it's not 5-7w because it's gray non-inductive fuseable.
more like 3w

[mentholflash]

Re: Aoyue 738 4 in 1 solder station power board



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

[stj]

Re: Aoyue 738 4 in 1 solder station power board

check the 5v circuit

[redwire]

Re: Aoyue 738 4 in 1 solder station power board

it's not 5-7w because it's gray non-inductive fuseable.
more like 3w

It's long at 26-28mm and almost 8mm dia., out of china that would be a 5W mox. for the size.
Another way to look at it, assuming it's in series with the heater for some silly weird reason, 600W heater 2.5A 240VAC gives 7.5W on a 1.2Ω resistor in series. But it's (heating element) not on all the time, so maybe it works in the bowels of guangdong.