Bakon 950D "Extra Crispy" mod (19->24 Volt)

[Th3_uN1Qu3]

Hello, you fine folks.

I've been hearing good things about the Bakon 950D (what a funny name!) soldering station with T12 tips (mistakenly labeled as T3 or T13, i see), so I thought i'd order one and a set of various tips.

The station arrived a couple weeks ago and I was pretty impressed with it, but I wondered if it could do just a little bit better. The replacement tips have arrived last week, just need to pick the package up. Anyway, on to the bacon (pun intended)!

I have noticed that it is usually labeled as 75W. Well, mine is labeled as 50W, so I took it apart to take a look.

The station is made of 2 boards, the power supply and the iron controller. The control chips used are the OB2202 quasi-resonant flyback controller on the primary side and the classic TL431 for feedback. An IRF840 is used as the primary switching device, a 100 volt 20A schottky diode (forgot the number) for rectification, and an AOD425 P-Channel mosfet does the PWM switching of the iron for temperature control. There is also an Atmega processor running the show and a 78M05 regulator providing the iron controller board with power.

The internal build quality is really nice, i was definitely not expecting a full line filter, all big-brand semiconductors (wow! ) and a modern power supply design for the price ($27). The caps are all cheap China brands, but hey, you're getting a lot for your $$.

The power rating on this station I think is the input power rating, because the included tip measured in at roughly 8.8 ohms, and the power supply put out 19.25V which would be an output power of 42.1W to the tip at full drive. So I thought i would boost the power supply to 24 volts, which should be easy, since this is a flyback type supply.

Once i took the iron control board out and read the part number off the P-channel mosfet that is regulating the temperature of the iron by PWM, I noticed that I also had another problem that needed to be addressed before boosting the voltage - the gate of this mosfet was driven by another transistor down to ground, and this device had a 25V gate rating, making 24 volts way too close for comfort.

Since the switching frequency of the PWM is very low, the solution was simple: adding a Zener diode in series with the gate (thanks Chris!). I chose a 5V1 zener, which will keep the gate drive voltage very close to the original. I didn't want to cut the trace so I desoldered and tried pulling up the gate terminal, but the package ended up cracking and the mosfet was damaged. Oops. I replaced the FET with a suitable one from a laptop board. I advise you to cut the trace instead.

Ok, now with that taken care of, time to mod the power supply. The bottom feedback resistor of the TL431 (R24 on the board) was 4.42k. I did the math and it solved to another 15k resistor in parallel with that to give me an output of roughly 24 volts. I soldered the additional resistor on top of the original one. A nice touch is that the turns ratio is printed on top of the transformer, which is 60:8:8 (primary:secondary:auxiliary). So, the auxiliary winding is 1:1 with the secondary. The maximum allowed voltage for the controller chip is 31 volts, so this modification should cause no further complications.

I plugged the iron in, turned it on, the display flashed briefly then quickly went out, and no further signs of life. I measured the primary switching device and it read a near-short from gate to source, so I took it out to verify, but there was no more short either on it, or onto the board. I put the IRF840 back in, removed the 15k resistor and the iron turned on no problem. This must have been the work of some protection circuit... Checking the datasheet of the OB2202 controller showed that it's got an overvoltage protection, which is sensed from the auxiliary winding thru R10 and R11 on the board. Since the aux winding is 1:1 with the secondary, R11 needed to be adjusted down by the same ratio as R24, to change the OVP threshold so it does not trigger at 24 volts output. This solved to an extra 91k resistor in parallel to R11, which I soldered on top of it like for the other one. After this modification was done, the power supply stayed on at 24V.

The output voltage is now 24.14 volts, which should give roughly 66 watts output. This iron was pretty good until now, now it is GREAT! Heats up in no time and handles everything I throw at it with ease. Can't wait to pick up the package with the different tips!

Thus, I present you the "Extra Crispy" mod, because what name would be more fitting for a soldering iron called "Bakon"!

[vinceroger69]

Thanks, this mod looks good ive just got one of these irons mine came with a t13 handle so ive just swopped it to a t12 i certainly will try this mod once i can find the parts needed.

[stj]

the reason for the name is simple, everybody knows that everything is better with bakon.

btw, the output caps are 25v rated - get ready for the boom!
and very few 35v rated ones will fit - maybe panasonic FS and one or two from nichicon or chemicon.
your also pushing the limits of the 5v regulator.

all this and more was covered on kazus forum.

[stj]

in your photo your handpiece is a T13 btw.

[Th3_uN1Qu3]

Originally Posted by stj

btw, the output caps are 25v rated - get ready for the boom!
and very few 35v rated ones will fit - maybe panasonic FS and one or two from nichicon or chemicon.
your also pushing the limits of the 5v regulator.

I know the output caps are 25V. But this is not a device that stays powered all the time. If/when they blow, i'll just replace them. It's a cheap, easily serviceable piece of kit.

Don't see any issue with the 5V regulator. It's a 78M05, it can take up to 35V input. The load demands are not high on it either.

Originally Posted by stj

in your photo your handpiece is a T13 btw.

We'll see today if the tips fit then.

[vinceroger69]

so this mod should be ok if we change the two output capacitors for 35 volt ones im placing a order later for some parts any suggestions on what capacitors too use that fit the board 2 x 1000Uf 25v 10x20mm i think if i remember from stj thread on this iron

[Th3_uN1Qu3]

If you can't find 1000u caps small enough to fit, you should be able to go down to 680u/35V with no issue if you use good quality, low ESR capacitors. The ones that are fitted are generic ones.

[vinceroger69]

thanks i will have a look on rs website the bakon is just my spare station as i use the quicko 951 station more if im honest but handy having two irons for smd removal etc.
https://www.aliexpress.com/store/pro...858580702.html

[Th3_uN1Qu3]

That looks like a pretty beefy power supply on that kit.

[vinceroger69]

yes kit seems to work ok, it does have the odd error message beeps etc when using new tips, but once you get past the error and tin the tip it holds a stable temperature fine and when swopping tips to another used one no more errors.
This is the replacement handle i used for the bakon i used the bakon wire just unsoldered plug end and used the bakon plastic tip holder as better quality.
https://www.aliexpress.com/item/9501...56c74c4dFjUNAv

[stj]

some stuff looted from kazus

my badly translated notes:
------------------------------------
About the conversion to 24V.
You do not need to twist the turn on the transformer.
We change the two output capacitors 1000uF 25V to 1000uF 35V,
parallel to the current resistor in the primary we add a resistor to 2.7 ohms,
TL431 (change-add), to get 24V output,
At the input of the stabilizer 7805 add a zener diode to 5.1V (knock down 5 volts, To reduce the heating of the stabilizer),
for safety we change the inter-winding capacitor to Y1 safety-class.
You can, but do not necessarily change the transistor to a higher voltage (I put STP9NB60)



Yet we must not forget about the replacement of R11, or the ob2202 will go into protection.
replace by:
R24 3.6 kOhm
R11 22kω on
As a result, the output is 23.2 V.
-----------------------------------------------------

[Th3_uN1Qu3]

I ended up with R24 ~3.4kOhm and R11 21.8kOhm. No need to change current limiting resistor in primary, maybe with 110V input it is necessary but for European mains voltage, no issue.

[vinceroger69]

Originally Posted by Th3_uN1Qu3

I ended up with R24 ~3.4kOhm and R11 21.8kOhm. No need to change current limiting resistor in primary, maybe with 110V input it is necessary but for European mains voltage, no issue.

can you mark on the picture you posted where too make the cuts in the trace as will help myself and other users too as dont want too get it wrong thanks.

[robca]

Originally Posted by Th3_uN1Qu3

I ended up with R24 ~3.4kOhm and R11 21.8kOhm. No need to change current limiting resistor in primary, maybe with 110V input it is necessary but for European mains voltage, no issue.

Old thread, I know, but one can always hope for a reply

I plan to make this change: I really like my 950D, but it's a bit anemic for some of the soldering I do, and I'm forced to keep cranking up the temperature, which is a bad idea

I live in the USA, so 110V mains here. Which one is the current limiting resistor, and what values should I try to use?

[Th3_uN1Qu3]

Will have to take it apart again for that, as the zener obscures the view.

You can use your multimeter to find it. Right-hand side of R30, towards the edge of the iron control board, connects to gate of Q3. You can either cut the trace as it goes out of there, or desolder R30 and move it so only the pad on the left side is making a connection. Then you connect the zener between the now open end of R30 and gate of Q3, with the cathode (black bar) going into Q3.

[vinceroger69]

Originally Posted by Th3_uN1Qu3

Will have to take it apart again for that, as the zener obscures the view.

You can use your multimeter to find it. Right-hand side of R30, towards the edge of the iron control board, connects to gate of Q3. You can either cut the trace as it goes out of there, or desolder R30 and move it so only the pad on the left side is making a connection. Then you connect the zener between the now open end of R30 and gate of Q3, with the cathode (black bar) going into Q3.

Thanks i will order the capacitors and two resistors then will try this mod.

[vinceroger69]

Originally Posted by Th3_uN1Qu3

Hello, you fine folks.

I've been hearing good things about the Bakon 950D (what a funny name!) soldering station with T12 tips (mistakenly labeled as T3 or T13, i see), so I thought i'd order one and a set of various tips.

The station arrived a couple weeks ago and I was pretty impressed with it, but I wondered if it could do just a little bit better. The replacement tips have arrived last week, just need to pick the package up. Anyway, on to the bacon (pun intended)!

I have noticed that it is usually labeled as 75W. Well, mine is labeled as 50W, so I took it apart to take a look.

The station is made of 2 boards, the power supply and the iron controller. The control chips used are the OB2202 quasi-resonant flyback controller on the primary side and the classic TL431 for feedback. An IRF840 is used as the primary switching device, a 100 volt 20A schottky diode (forgot the number) for rectification, and an AOD425 P-Channel mosfet does the PWM switching of the iron for temperature control. There is also an Atmega processor running the show and a 78M05 regulator providing the iron controller board with power.

The internal build quality is really nice, i was definitely not expecting a full line filter, all big-brand semiconductors (wow! ) and a modern power supply design for the price ($27). The caps are all cheap China brands, but hey, you're getting a lot for your $$.

The power rating on this station I think is the input power rating, because the included tip measured in at roughly 8.8 ohms, and the power supply put out 19.25V which would be an output power of 42.1W to the tip at full drive. So I thought i would boost the power supply to 24 volts, which should be easy, since this is a flyback type supply.

Once i took the iron control board out and read the part number off the P-channel mosfet that is regulating the temperature of the iron by PWM, I noticed that I also had another problem that needed to be addressed before boosting the voltage - the gate of this mosfet was driven by another transistor down to ground, and this device had a 25V gate rating, making 24 volts way too close for comfort.

Since the switching frequency of the PWM is very low, the solution was simple: adding a Zener diode in series with the gate (thanks Chris!). I chose a 5V1 zener, which will keep the gate drive voltage very close to the original. I didn't want to cut the trace so I desoldered and tried pulling up the gate terminal, but the package ended up cracking and the mosfet was damaged. Oops. I replaced the FET with a suitable one from a laptop board. I advise you to cut the trace instead.

Ok, now with that taken care of, time to mod the power supply. The bottom feedback resistor of the TL431 (R24 on the board) was 4.42k. I did the math and it solved to another 15k resistor in parallel with that to give me an output of roughly 24 volts. I soldered the additional resistor on top of the original one. A nice touch is that the turns ratio is printed on top of the transformer, which is 60:8:8 (primary:secondary:auxiliary). So, the auxiliary winding is 1:1 with the secondary. The maximum allowed voltage for the controller chip is 31 volts, so this modification should cause no further complications.

I plugged the iron in, turned it on, the display flashed briefly then quickly went out, and no further signs of life. I measured the primary switching device and it read a near-short from gate to source, so I took it out to verify, but there was no more short either on it, or onto the board. I put the IRF840 back in, removed the 15k resistor and the iron turned on no problem. This must have been the work of some protection circuit... Checking the datasheet of the OB2202 controller showed that it's got an overvoltage protection, which is sensed from the auxiliary winding thru R10 and R11 on the board. Since the aux winding is 1:1 with the secondary, R11 needed to be adjusted down by the same ratio as R24, to change the OVP threshold so it does not trigger at 24 volts output. This solved to an extra 91k resistor in parallel to R11, which I soldered on top of it like for the other one. After this modification was done, the power supply stayed on at 24V.

The output voltage is now 24.14 volts, which should give roughly 66 watts output. This iron was pretty good until now, now it is GREAT! Heats up in no time and handles everything I throw at it with ease. Can't wait to pick up the package with the different tips!

Thus, I present you the "Extra Crispy" mod, because what name would be more fitting for a soldering iron called "Bakon"!

in picture 4 where are you measuring the output voltage thanks

[stj]

output voltages are on the connector leading to the controller/display pcb - look at the schematics i posted.

btw, if any cap is going to fit, it's a Panasonic FS
eeufs1v102L
farnel:2766954
RS:145-8557 (x10)

but they werent cheap last time i checked!

[vinceroger69]

Originally Posted by stj

output voltages are on the connector leading to the controller/display pcb - look at the schematics i posted.

btw, if any cap is going to fit, it's a Panasonic FS
eeufs1v102L
farnel:2766954
RS:145-8557 (x10)

but they werent cheap last time i checked!

i have got 2 rubycon 35v 680uf 35ZLH680MEFC10X23 Th3_uN1Qu3 suggested may work whats your thoughts? and thanks i missed the schematic

[stj]

so uN1Qu3,
what tips did you order??