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

[stj]

R24,
russians replaced it with 3k6 for 23v
un1qu3 bridged the original 4.42k with 91k

3k3 is going to give well over 24v

[Th3_uN1Qu3]

91K goes in parallel with R11 (OVP) not R24 (feedback). 15K is in parallel with R24 (originally 4.42k) which gives 3.414kOhms as a final value for R24.

But yes, I agree, 3k3 is too low. 3k3 for R24 would give an output of 24.94V. Precision is needed here. That is why I decided to add a resistor in parallel, because I did not have the required calculated value.

[dssence]

Originally Posted by Th3_uN1Qu3

91K goes in parallel with R11 (OVP) not R24 (feedback). 15K is in parallel with R24 (originally 4.42k) which gives 3.414kOhms as a final value for R24.

But yes, I agree, 3k3 is too low. 3k3 for R24 would give an output of 24.94V. Precision is needed here. That is why I decided to add a resistor in parallel, because I did not have the required calculated value.

Thanks for all the help. I finally managed to solve the issue when it didn't turn on. Now it turns on and off without having to discharge the primary electroyltic.
I did by replacing r11 by two resistors of 10k in series giving around 19.8k ohms.
Now here goes the problem, the unit sometimes starts to heat the tips and sometimes doesn't. I can hear PWM triggers sometimes and sometimes it get stuck. Any ideas about this? . I can't understand why something so simple get so complicated for me. Many people did the mod without any issues. I added the zener to the gate on the other board cutting the gate trace fine. Replaced the caps 100uf x 35 and the resistors. Can't happen to understand what could be going on. Waiting for your help.
I thought it could well be the trimmer on the other board, so I played around , but still no noticeable changes.

[vinceroger69]

did you mean 1000uf 35v? you put 100uf

[dssence]

Originally Posted by vinceroger69

did you mean 1000uf 35v? you put 100uf

Yes sorry 1000uf was just a typo. yes I replaced by 1000uf x 35. I think I'm going to revert all the mod and see if this still happens.

[vinceroger69]

i have got all the parts to carry out this mod but as your having these issues i may leave my unit untouched for now

[dssence]

Originally Posted by vinceroger69

i have got all the parts to carry out this mod but as your having these issues i may leave my unit untouched for now

Going to wait for Th3_uN1Quo3 see what could be wrong.. Still waiting for him

[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?

[Daijoubu]

Dead thread revival, plan on doing this mod myself

R11, either replace with 20k or put 100k in parallel (21.25k)
R24, going to put 20k in parallel to get 3.6k ~23V/62W output

The 2.7 (2-3ohm) is for the R1 shunt, to reduce it down to 0.2-0.24V

Someone said to also swap R19 to 1k as to not kill the LED inside the TL431 optocoupler

Use Google Translate and look at the comments below

https://mysku.club/blog/china-stores/40868.html
https://mysku.club/blog/discounts/44292.html

[stj]

so,
R11 - 27k(OVP) change to 20k 0805
R24 - 4.42k(voltage reference) change to 3.4k 0805

i'v been running 24v for several years and not damaged the optocoupler
the caps you need are panasonic eeufs1v102L

you need a 5v1 zener diode on the control board,
here is a couple of photo's - with a track cut and then bridged by the diode

[redwire]

I see upgrades to Panasonic FR/FS but what's with the tantalum lol

[stj]

the tant was factory.
i upgraded the Y class on the right.

[Daijoubu]

Originally Posted by stj

so,
R11 - 27k(OVP) change to 20k 0805
R24 - 4.42k(voltage reference) change to 3.4k 0805

i'v been running 24v for several years and not damaged the optocoupler
the caps you need are panasonic eeufs1v102L

you need a 5v1 zener diode on the control board,
here is a couple of photo's - with a track cut and then bridged by the diode

First thing I did was to replace the caps, I had some spare ones from previous recapping job, wasn't planning on getting SMD resistors, I just placed 2 orders with Digikey but your mod looks so neat haha that I may end up spending another $100 for free shipping, could use some extra PSUs...wife is going to kill me

What should I be looking for the Y class cap?

What about the 7805? Have you done anything to it?
I think i'm gonna swap it for a small switcher and get rid of the R26 2R and VD7 zener diode

[stj]

the 7805 is fine, you dont need to upgrade the y-class either.

all i remember doing was the 2 resistors and the electrolytics + the zener on the other board.

[Daijoubu]

I swapped the 7805 for a switcher, it's an OSKJ board based on the MP2315 (max 24V lol)
The caps I have are Rubycon ZLH 25V, hope they don't blow up, I'm gonna order the FS-A eeufs1v102L as spares

I had some 20k 0805 SMD resistors so I used those

R11 swapped for 20k
R24 20k parallel (found out I had some 362 afterwards, oh well)

Measured 23V output.

To fit the board underneath, I had to trim out the bottom wall mounting keyhole flush
Converter have 20uF on both input and output, so I just added back the 22uF on the output (notice the orientation C16 + and C15 -)

Ripped off a trace, the Weller I borrowed wasn't such a joy to use lol

Trace have been cut


As for the R26 2ohm resistor, can it be removed or not? How about the D7?

[stj]

why touch r26 or d7??
good luck with the buck convertor if it's max input is 24v - it may last but who knows.

[Daijoubu]

Originally Posted by stj

why touch r26 or d7??
good luck with the buck convertor if it's max input is 24v - it may last but who knows.

It's what was feeding the 7805, at least according to the schematic.

The MP2315 appears to be a good modern IC, went into protection mode at 40V and died at 45V, so there's plenty headroom haha
https://www.youtube.com/watch?v=4iAgaBzpOCE&t=230s

[Th3_uN1Qu3]

Originally Posted by Daijoubu

I swapped the 7805 for a switcher, it's an OSKJ board based on the MP2315 (max 24V lol)

Don't do that again. The 78xx series have been around longer than I've been, and they're super stable and super reliable. There's gotta be a reason why they're still in active production.

Everything else looks good, but you had no business messing with that linear regulator. It does the job it was intended to, no issues.

[Daijoubu]

Originally Posted by Th3_uN1Qu3

Don't do that again. The 78xx series have been around longer than I've been, and they're super stable and super reliable. There's gotta be a reason why they're still in active production.

Everything else looks good, but you had no business messing with that linear regulator. It does the job it was intended to, no issues.

Just to lower the overall heat inside the enclosure lol

I'm running into the problem where it shuts off after a while and I have to wait for the capacitor to discharge before I can turn it back on, is that the OVP kicking in? Should I try to lower R11? Or an issue with the optocoupler? It might have done that even before I did the 23V mod.

I have been powering the iron/controller board with an external 24V supply and it works fine (with the same MP2315 buck converter).

I've swapped the TL431, put in a Y cap and the 35V capacitors so far lol

[stj]

whats your mains voltage?
and about that buck convertor, did you but the track for the pot and bridge the pads for 5v?