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**R_J** · 11-25-2022, 02:39 PM

Re: Understanding air conditioner PSU logic

+12volts and +5 volts are supplied by the smps on page 72, likely bad ic1 and shorted M1. The schematic is hard to read but I suspect PTC1 could be open. If PTC1 is open I suspect K5 relay contacts could be bad.
Also check RS1
If there was a short on the module board it was likely IC8 shorted or the main drive ic PM1

**Gjackson** · 11-25-2022, 03:30 PM

Re: Understanding air conditioner PSU logic

Thanks for your reply, PTC1 is not open and is in fact 40ohm I'm not sure if that's a good reading as it seems a little high. RS1 checks out fine too. I'm getting 160VAC after PTC1 which I'm not sure should be the case I would expect it to be closer to 220. This results in 220VDC after rectification which is still too low. Am I looking at a fault PTC relay?

thank you

**lotas** · 11-25-2022, 03:48 PM

Re: Understanding air conditioner PSU logic

Is the circuit more like an inverter, is the inductor connected to the board? Power passes through it to the diode bridge (sometimes there are two bridges) and a powerful IGBT transistor and to power capacitors, and the main power supply is already powered from them (check the IGBT for a short circuit).

**R_J** · 11-25-2022, 03:50 PM

Re: Understanding air conditioner PSU logic

What is the a/c voltage before the ptc? You need to check between Neutral CN6 and CN5, then check between CN6 and CN9
CN8 and CN9 supply the bridge rectifier BG1, The ac could be low because it is dropped by PTC1 until K5 shorts it out.
You should have around 220 VDC across CN5 (N, ground) and CN1 P
This voltage will be enough to power the smps circuit for the low voltage +5, +12, +15

**Gjackson** · 11-25-2022, 04:05 PM

Re: Understanding air conditioner PSU logic

voltage at input of bridge is 160VAC which as you said is caused because of PTC voltage drop and between CN7 and CN5 which are the bridge outputs is 220VDC, currently this never reaches the P and N terminals as I have the inductor between CN7 and CN6 removed as it is inside the air conditioner housing and is disconnected, However going off of what you said, once I reconnect that inductor relay K5 should switch and short out the PTC giving full 310 to the caps. My main concern really was that the initial 220VDC would not be enough to generate the 12v 15v 5v rails needed for K5 to switch but you have answered that

I'll try it out when I get the chance to mount the boards back into the housing.

Thank you!

**R_J** · 11-25-2022, 04:12 PM

Re: Understanding air conditioner PSU logic

Yes, you will need to connect the inductor to get voltage across P and N. Page 72 shows the smps, it will operate with a wide range of dc input.
You will need the smps to be working before K5 will operate

**lotas** · 11-25-2022, 04:18 PM

Re: Understanding air conditioner PSU logic

Well, instead of an inductor, you can put a jumper for diagnostics, you won’t start some outdoor units until you briefly apply the “L” phase to the control “S” (signal, interconnect output).

**sam_sam_sam** · 11-26-2022, 12:59 AM

Re: Understanding air conditioner PSU logic

I am surprised that this manual has this information in it most of them do not

**Gjackson** · 11-26-2022, 01:59 AM

Re: Understanding air conditioner PSU logic

Originally posted by sam_sam_sam View Post

I am surprised that this manual has this information in it most of them do not

Absolutely, I was surprised myself when I saw that schematics where available.
+1 for Haier

**Gjackson** · 11-28-2022, 11:31 AM

Re: Understanding air conditioner PSU logic

Update: I attached both boards back into the outdoor unit and tried powering up but no luck

voltage on main filter capacitors starts rising slowly and eventually plateaus at around 20VDC, at this point I'm suspecting the PTC relay and it's high resistance. Might not be important but I also hear a soft clicking occuring every 1/2 a second or so which might be the PTC relay? It's strange as this board stopped working after I replaced 3 capacitors on the output of the 15v smps which were clearly bloated and I don't know how I could have killed the board honestly. The board would still power on without the new caps just no 15v would be present.

**R_J** · 11-28-2022, 03:25 PM

Re: Understanding air conditioner PSU logic

I could start by posting clear in focus pictures of both sides of the board. Is the board double sided? If it is you may have damaged a trace when removing the capacitors.
The ptc relay? high resistance? Do you mean K5 ? what resistance are you checking? the relays coil or across its contacts?
The inrush ptc1 is likely a PPL20400 (40Ω)
If you only get around 20 volts across the 680µf/400v caps, you may have damaged the smps and it is drawing too much current and dropping too much voltage across the ptc1 inrush thermistor

**Gjackson** · 11-28-2022, 03:40 PM

Re: Understanding air conditioner PSU logic

No traces were damaged I made sure of that. Apparently PTC1 is what's called a PTC relay mainly used in HVAC, never heard of it before but it's the only thing in the way of 240VAC mains reaching the module board. the 40ohm I measured where across it's contacts.

it looks exactly like the one here and is soldered on the PCB: https://www.indiamart.com/proddetail...113490830.html

as for pictures I currently don't have the board on hand.

Attached Files

**R_J** · 11-28-2022, 04:00 PM

Re: Understanding air conditioner PSU logic

PTC1 is an INRUSH THERMISTOR, it is NOT a relay. I know the hvac people call it one. K5 is the relay
Inside that black case is a thermistor disk mounted between two contacts

Have you checked if you get +15v, +5VD or +5V on the smps with CN22 removed?

I'm interested in this as the module board had a short on it

Did you replace the module board and if not, what was shorted?

Attached Files

**Gjackson** · 11-28-2022, 04:08 PM

Re: Understanding air conditioner PSU logic

I see, that clears up a lot of questions. Highly possible that I killed something from the heat of the soldering iron. The smps is not the most well designed part of the board and it operates at way too high temps. All images I found online as well as my unit have clear discoloration due to heat so it was probably on the brink of dying. I have checked if I get voltage without the module board connected and I still don't so it's definitely a fault on the larger control board.

thanks for helping me out.

**R_J** · 11-28-2022, 04:16 PM

Re: Understanding air conditioner PSU logic

If I could see the pictures you are referring to...

**lotas** · 11-28-2022, 04:16 PM

Re: Understanding air conditioner PSU logic

Check the IGBT transistor for a short circuit (and +15v power is important for it).

Attached Files

**Gjackson** · 11-28-2022, 04:20 PM

Re: Understanding air conditioner PSU logic

https://www.youtube.com/watch?v=dFvxQvKanUc&t=186s

this video shows same boards, couldn't find one in english.

below is a pic of the smps circuit as well as the 3 caps I replaced circled in blue.
I suspect IC is dead as I didn't find a short on the FET, no short on the IGBT lotas mentioned either

Attached Files

**R_J** · 11-28-2022, 04:39 PM

Re: Understanding air conditioner PSU logic

If the 3 caps were bulged I would also replace E3 22µf/25v as it is most likely bad causing the smps not to start.
Measure the DC voltage across E3 it could give an indication of the state of the ic.

**Gjackson** · 11-28-2022, 04:56 PM

Re: Understanding air conditioner PSU logic

I suspected E3 initially also so I removed it and checked it but it tested fine so I put it back in. I did not measure the voltage on it however so that will be the next step. According to IC datasheet VCC is generated by the IC from the HV so if that's not present then the chip is dead

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Understanding air conditioner PSU logic

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