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Topic: Really universal soldering controller (Read 817826 times) previous topic - next topic

Re: Really universal soldering controller

Reply #2010
Power meter behaves really weird. Did you tried without the sensor board? Maybe there some extensive leakage. Also, check graphs of the PC software, maybe it'll lit some light into a situation.

Re: Really universal soldering controller

Reply #2011
These transistors are the part of opamp feedback loop, so it doesn't matter if they differ, even a couple of ohms Rds.on shouldn't matter, besides, OLED is working and its power is switched by the same mosfets.

Re: Really universal soldering controller

Reply #2012
[quote author="vulkan35"][quote author="afedorov"]Power meter behaves really weird. [/quote]

Removed the transistors Q18, Q19, Q21, Q22 from the board all have different readings. Remained in tape 4 pieces IRLML6401 and they proved defective, will order new.[/quote]

Hello, vulkan35
replace suspected mosfets and if you still have the same problem (it looks like bad solder joint),
first disconnect touch sensing board (as afedorov mentioned) and continue your work without it ( connect it when all other is ok),
 re solder with soldering iron using good flux all suspected places of U10, U12, U16, U18, U13, U11, U15, U17 and surrounding components. Check also if you have good soldering of the controller's pins.
Check all cable connections from pin to pin of the board, not by ends of the cables.
Check if Outer shell (green wire) is good connected to EARTH and SENSEB.

Re: Really universal soldering controller

Reply #2013
Quick question: Does everybody attach their crystal case to ground?

Re: Really universal soldering controller

Reply #2014
I've soldered it to ground. But crystals can be easily damaged by overheating, so if you not sure - leave it as is.

Re: Really universal soldering controller

Reply #2015
I tried briefly, but the smooth stainless casing is proving hard to solder to. I might try again after maybe sanding the case slightly to make the surface more rough. But for now I will leave it if it's not critical.

Re: Really universal soldering controller

Reply #2016
I have a couple of 5mOhm WSL3637 shunt resistors lying around. Is it also possible to use this value instead of the 3mR/4mR version as specified in the BOM and scale the appropriate gain resistors accordingly? Or will the power dissipation be too large?

Thanks!

Re: Really universal soldering controller

Reply #2017
[quote author="aimpertro"]I have a couple of 5mOhm WSL3637 shunt resistors lying around. Is it also possible to use this value instead of the 3mR/4mR version as specified in the BOM and scale the appropriate gain resistors accordingly? Or will the power dissipation be too large?
Thanks![/quote]
Definitely doesn't worth. You will have a mess with current and temperature alignment, it will be also nightmare, if you got other assembling problems together with that, for some bucks more and 1 or 2 weeks waiting, you will save much more troubles!

Re: Really universal soldering controller

Reply #2018
Hi, aimpertro

Yes, R37, R43 2.5K for 5mOhm WSL3637 will be OK. You must use 0.1% resistors.
e.g. 2mOhms not recommended.

Tony

Re: Really universal soldering controller

Reply #2019
[quote author="Tony"]Hi, aimpertro
Yes, R37, R43 2.5K for 5mOhm WSL3637 will be OK. You must use 0.1% resistors.
e.g. 2mOhms not recommended.
Tony[/quote]
Hello Tony, when I built mine, even I had  3mOhm WSL3637, the temperature alignment was outside of pot Rc2 regulation.
How was yours?
Anyway, the current function over shunt is linear, but did you measure the max current, or at least Vshunt and compare it to display readings?

Re: Really universal soldering controller

Reply #2020
Ok, so tonight I tried to power up the back board. It turns out that my toroidal transformer actually puts out 27.2 volts at 238V mains voltage. Is that to be expected for a 230v, 120VA, 24v transformer?

Anyway, I connected the board to the transformer, and unfortunately I do not get correct readings when measuring at J3. between the 3.3 pin and gnd i read 0.02 volts. Not good.

Some measurements I took:

across the TVS: 11.42V
across the diodes: 14.98V
C1: 11.52V
I tried a few other C's but they read fractions of volts at best.

Can anybody give me some advice as to where and what to measure next to find the root cause?

I did have to solder Q2, Q8 directly to the vias (see a page back), but they do not appear to be shorted when doing a continuity test. would these mosfets be a possible cause of the bad readings?

Re: Really universal soldering controller

Reply #2021
Hello Doomedahab,
first disconnect the front board and check again C1 voltage and if it the same, check fuse, if D1 to D4 are correct positioned, if you connect Trf. to J1 and remove TVS temporary to measure Vc1.

Re: Really universal soldering controller

Reply #2022
[quote author="minkok"]Hello Doomedahab,
first disconnect the front board and check again C1 voltage and if it the same, check fuse, if D1 to D4 are correct positioned, if you connect Trf. to J1 and remove TVS temporary to measure Vc1.[/quote]

Thanks Minkok!

All measurements were without the front board attached. D1-D4 are oriented correctly. I already inspected the fuse, and replaced it to be sure. The fuses look undamaged. It's a clear glass version with a thin wire so it would be easy to spot if it would have popped. There is however virtually no voltage across its terminals.

I will remove the TVS tonight and re-measure C1

Re: Really universal soldering controller

Reply #2023
Without TVS voltage across C1 is 11.53V, no difference.

Q2: 10.95V
Q8: 8.46V
Q10: 0.2V
Q11: 1.64V

Q10 seems suspect?

Edit: Q12 reads 11.6V

Re: Really universal soldering controller

Reply #2024
[quote author="Doomedahab"]Without TVS voltage across C1 is 11.53V, no difference.

Q2: 10.95V
Q8: 8.46V
Q10: 0.2V
Q11: 1.64V

Q10 seems suspect?

Edit: Q12 reads 11.6V[/quote]
Measuring voltages before D6 with DMM is pointless - there is unsmoothed rectified AC voltage. Do measurements on cathode of D6 and on C6. Be careful around U1 as probe could easily slip and short Vin to 3.3V rail.
Did you connect the transformer to AC connector? If it's connected to DC one, you'd only have a half-period and a half of input voltage.