Seems it needs at least 12mA load to regulate.. According to the datasheet it should be able to output 500mA at 12.3v. Have you any smaller value resistors, in the 100-500ohm range, to put in parallel make around 80 - 100 ohms, so we can prove the chip is actually regulating properly...

With 100 Ohms resistor, output is 10.64V

 

So, i left that resistor of 1k ohms there, and attached the control board, it beeps once and turns off, and when i plug out and in again, it just short half beep... I measured the voltages, it gets like 11 someting volts, but after AMS1117 3.3 it is like 1.5V so i guess there is another issue too! who makes these tings..

 

With 100 Ohms resistor, output is 10.64V

Hmmm, 11v & 100ohm is 110mA, way below what that chip should deliver...

So, i left that resistor of 1k ohms there, and attached the control board, it beeps once and turns off, and when i plug out and in again, it just short half beep... I measured the voltages, it gets like 11 someting volts, but after AMS1117 3.3 it is like 1.5V so i guess there is another issue too! who makes these tings..

1.5v suggests there is too much current being drawn by the rest of the circuit, probably because there is a board fault. eg a dead processor Given the history of this I think that, sorry to say, the whole thing is toast and you've gone as far as you practically can.

 

Hmmm, 11v & 100ohm is 110mA, way below what that chip should deliver...


1.5v suggests there is too much current being drawn by the rest of the circuit, probably because there is a board fault. eg a dead processor Given the history of this I think that, sorry to say, the whole thing is toast and you've gone as far as you practically can.

Hmm, but why does it work on 9V... When i connect it to 9V battery, buttons work, I can turn it on and off... Thats what bugs me because when on battery, ams1117 outputs 3 and something wolts as it shoud...

 

I placed 10ohm resistor here, and it worked for a bit, but then stopped again

 

Eh, I tried connecting it to 12V, and there was a shor... and main IC has blown, so I guess this is really the end...

 

I'm going to buy new thermostat with the relay, but the new thermostat has one relay that's 10A, and the heater element is 2X1000W, so I need some workaround to make it work with 2 relays, because I'm not sure if one relay of 10A can handle 2000W for a longer period of heating..

The new thermostat is 220V 10A, so I can't really connect it to those 2 12V relays on board and then switch power via switch for 1000 and +1000w heater...

 

what is new thermostat, link?

 

what is new thermostat, link?

https://www.amazon.com/Temperature-Controller-Thermostat-Ac110-220v-Highprecision/dp/B0CSW5ZVKJ

220V one

 

what is new thermostat, link?

This is my plan. So relay for High and low Setting for the heater is controlled by those 2 pins, thermostat regulates low relay, and then switch turns on the high setting. When teperature is reached, both relays are off by thermostat's rekay, regardless if switch for high is on or off, it will turn off and on by thermostat either way.

Let me know if this is good solution?

 

This is the thermostat

 

Errr... that looks like the 12v DC version, not the 220v AC version. I don't see any AC/DC conversion on that PCB.

Was it bought new? Looks pretty poorly made to me.. what with the melted plastic and all the gunk on the PCB around the switches?

 

Errr... that looks like the 12v DC version, not the 220v AC version. I don't see any AC/DC conversion on that PCB.

Was it bought new? Looks pretty poorly made to me.. what with the melted plastic and all the gunk on the PCB around the switches?

It says on the package/plastics 220...

The melting and gunk is me trying to replace relay with the better one...

It's new... There is AP8505 MOSFET, on the right side of the screen, so maybe that's how it gets it's voltage down..

 

Ah, right, the AP8505 is indeed a small AC/DC smps controller, not a MOSFET, similar to the PN8024 but doesn't need the external diodes just the inductor. But the PCB clearly says 12v! I was looking for the bridge rectifier/large smoothing capacitors etc of a properly implemented AC/DC converter.

I think what they've done is arranged the PCB layout to work either way, with the 12v version not having the AP8505 populated and replaced with a link. To make that work they've done away with the input filtering, safety fuse, and the track clearances are very marginal for 220v. Completely contained in a plastic box its border-line OK for electric shock but one side of that external temperature probe could well be AC hot, so selling this in Europe/UK would be illegal.** I doubt it'll pass EMI/EMC testing either. Use it at your own risk, but personally I'd not give it house room.

**quick check on Amazon UK, the vast majority of these are DC only, though there is one supplier offering a 220v option.

 

Ah, right, the AP8505 is indeed a small AC/DC smps controller, not a MOSFET, similar to the PN8024 but doesn't need the external diodes just the inductor. But the PCB clearly says 12v! I was looking for the bridge rectifier/large smoothing capacitors etc of a properly implemented AC/DC converter.

I think what they've done is arranged the PCB layout to work either way, with the 12v version not having the AP8505 populated and replaced with a link. To make that work they've done away with the input filtering, safety fuse, and the track clearances are very marginal for 220v. Completely contained in a plastic box its border-line OK for electric shock but one side of that external temperature probe could well be AC hot, so selling this in Europe/UK would be illegal.** I doubt it'll pass EMI/EMC testing either. Use it at your own risk, but personally I'd not give it house room.

**quick check on Amazon UK, the vast majority of these are DC only, though there is one supplier offering a 220v option.

So that connectiondiagram is ok?

 

So that connectiondiagram is ok?

Yeah, that'll work.

Caveat. You must get the AC line the same way round on both boards, so that the 'ground' on both PCB are connected to the same AC wire. It's not obvious from the board markings which is which on the thermostat.

 

Yeah, that'll work.

Alright, time to assemble that, and see how it works... I mean it is what it is... maybe I should have bought 12V version, and attach it to the board directly, but im not sure how it will behave with that PN8024... so maybe this is better... WE will see how it works. Thank you!

 

DON'T DO IT. Further to my comment above,l I don't think this is a good idea at all... looking at how both are implemented... there is no common ground between them. The original circuit uses a full bridge rectifier while the new on uses a 1/2 wave solution. This will short L - N on alternate 1/2 cycles...

 

But both circuits are isolated from each other.. they both go to outlet 220V, and bothhave their own power supply. The thermostat only switches the relay that merges the 12V of the other board relay to enable it?thermostat is connected at the same outlet as the relay board

220V AC is plug, and both thermostat and the green board is connected to it...

 

Yes, you are right - my bad, I'd forgotten its a zero-volt contact.