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Topic: Really universal soldering controller (Read 707213 times) previous topic - next topic

Re: Really universal soldering controller

Reply #2895

But, I have got an interesting change. Now the iron starts heating, even when I am in cal mode! Before it just showed me the TC voltage without heating. Now it starts heating the instant I plug the iron + cartridge in, no matter if I am in cal mode or normal mode.

Another very interesting thing I absolutely cannot make sense of is the iron ID. When I connect the handle only (without cartridge), it correctly shows 24 5 as IDs. When the cartridge is inserted, this changes to 24 8, even though "JBC C245" is still displayed as tool in the top of the display. And, as I said, it instantly start heating, even in cal mode...
You got Q2 &/or not Q8 fail or driven incorrectly, needs to be checked for  failed  parts ( or bad connections, soldering ) , but first measure V over C10 and C18, in cal. mode they should be very close to 0V

Re: Really universal soldering controller

Reply #2896
Hi,

now, that is a very interesting thought, and it also seems to be the right place to start looking. Because, the voltage across C10 is 0,7 V, which in my opinion is everything else but close to 0 V. Tracing the problem back to the ┬ÁC lead me to a broken pulldown resistor for U3 (R21 was bad). Replacing it did not change anything, but ONOFF seems to be having a duty cycle of 50% (at least the voltage of the ONOFF trace is ~1,7 V, measured at U3A:2 and U5:2).

As I am writing this, I reflowed pins U5:2 and U5:3. That solved the temperature problem, indeed. Now, onto the next problem: the lab supply I'm using seems to struggle with providing the required power. It did work in the past, it's specified for up to 8 A, but I guess that's a problem not related to Unisolder but rather something I have to solve on my end. The supply is like 30 years old... Will report back testing with a different supply.

For now I really want to thank you guys for supporting me and leading me to the solution!

Re: Really universal soldering controller

Reply #2897
(at least the voltage of the ONOFF trace is ~1,7 V, measured at U3A:2 and U5:2).
It should be logic "0" (at least less than 0.8V ) in cal. mode. That's mean firmware or U5

Re: Really universal soldering controller

Reply #2898
Hi,

Just a quick update to those interested before I go to bed. I managed to get a few more problems aside, but some still remain.

It should be logic "0" (at least less than 0.8V ) in cal. mode. That's mean firmware or U5

Yes, that's what I tought. As I said, it was either U5:2 or U5:3, after reflowing it works properly now.

The temperature now rises beyond room temperature, but it is very, I don't know how I should call it... jerky? It jumps around wildly, every now and then a realistic temperature value pops up on the display, but mostly it's rubbish. I've tried to capture it with the software by logging the data through USB, I've attached the screenshots. "Calibration.png" shows the data acquired in calibration mode. Looks very good. "wCartridge.png" shows the data logged during heating. And this is the one making absolutely no sense to me. The ADC value looks perfectly fine. The "Current Temperature", "Filtered Temperature" and "PID Temperature" on the other hand make absolutely no sense to me. How is it possible that they deviate so much from the ADC value's behaviour?

Maybe I will find out something tomorrow...

Re: Really universal soldering controller

Reply #2899
In my opinion, you cannot do much, the only thing wasn't checked is a crystal osc.
Did you check Vref, I mentioned earlier?
All the rest is from U5, many ways to fail ( overheated, bad flash, is it china made )
If somebody can give other explanation

Re: Really universal soldering controller

Reply #2900
Faulty current temp calculation is the cause of everything else. This temperature is reset if
PV->Starting || PV->NoHeaterCnt || PV->NoSensor || PV->ShortCircuit
First should be false as controller is already started, Noheater and ShortCircuit also should be false as heater resistance just below 3 Ohm is correct and with no flickering, NoSensor also should be false as ADC reading seems to be fine.
Between ADC value and Current Temperature is heavy floating point math happening, probably something's going wrong there.
I tend to agree with minkok for a faulty MCU.

 

Re: Really universal soldering controller

Reply #2901
Hi,

I've done a few additional measurements, this time with a scope. And, by now I actuall tend to agree with both of you. All signals I measured look ok to me, everything points to a faulty MCU. First I did not believe it to be the MCU, because it was brand new, purchased at digikey or farnell (don't remember, but definitily either of the two), so I sure hope it's no chinese copy.
Sadly, I do not have a replacement at hand right now. But, I wanted to order a few things at digikey anyways, so I guess I'll just get another PIC and try to replace it. Will report back to you guys as soon as I have my replacement and soldered it in place.

Again, heaps and heaps of thanks to you guys for bearing with me! I really do appreciate it.

Edit: For completeness sake: Yes, the voltage reference is rock stable at 2,978 V. It is a little less than 3 V, but I guess it's ok. It would only lead to a slight offset in the termperature measurement.