Troubleshooting Daikin Inverter PCB Pt1

[ultimateinfinite]

Spider? Fuck. That. Shit.

[sjbrewy]

HI Aussie50, I have a Daikin exactly like this one and is doing the same thing, it wont work and those Led lights dont work. I got a fault from the remote control that is a u4- incorrect interunit wiring (interunit). outside not communicating with inside. Ive checked all wiring connections and plugs on power in/out and on the boards, but still not worky to make shore of good contact. Would it be that first PCB board stuffed, can it be fixed. is it worth fixn.Thanks

[Aussie50]

@sjbrewy I never bothered fixing the unit in the vid, jsut too hard.

I would suggest getting a Daikin tec to look at it. it could be a board in the outdoor unit or indoor.

[krisachar]

Nice video !

[mrjunior41]

this means when i want to repair my a/c i have to bring it first to a man ho can check the circuit board if not the circuit board i have to bring it to a man who can repair the gas leak or change the compressor.

[mrjunior41]

i thinking this thing of inverter a/c is making repairing of a/c more difficulty , it is not resulting as it should the board will die faster than the compressor & with out a board the compressor can't work

[spuddly01]

Do an ohms test from chassis to the 5 & 12V negative. If they one and the same then so be it - at least it will be easier to fault find.

I suspect the designer was US based or failed to understand the PSU spec sheets when designing. The spec sheets usually show a 110V mains due to the US based semiconductor market.

I'd be very surprised to learn they are using a ceramic resistor to drop the 240 to 110. Then again - built to a price...

The unload voltage is just due to design

sPuDd..

[Aussie50]

thanks mate!

I figured the control boards were a generic thing for all markets, powered with 110v. and the AC boards were dropped in at the factory to suit the market the unit was being shipped to, I'E 240 to 110 step down for our marked, and no step down for the US market.

I'll pull the board again and go anotehr video at some stage, right now I got other things to tackle.

[spuddly01]

Also you say "...I'm testing to ground..." in reference to your multimeter leads. I'm assuming you mean your meter -ve lead is connected to mains neutral or the chassis/electrical earth? Im wondering if this is upsetting your measurements. I would check and see if the 5 & 12V PSU negative is connected to earth/chassis. Most are not, they are floating secondary with a 2.2nF 3Kv ceramic cap holding it to half mains. (Except PC PSU's). Have a look around a modern VCR PSU. Same as the inverter PSU.

[Aussie50]

I'm testing to chassis ground, the PSU is earthed to the AC units chassis too..

I will do a test of the DC 5 and 12V rails to the PCB ground too..

Theres no step down trans, just the ceramic caps and high wattage resisters to limit current and voltage. its been ages since i did VCR PSU's but you are right about the design of the system!.

the fault is on the control board. when I remove the power lead from the main AC board, the voltage on the pins (yellow plug) goes up to 140v AC.

[spuddly01]

110Vac - odd. Almost like it was designed for the US voltage market. If I had it in front of me I could tell you if it was capable of 110/240.

So where does the 110Vac come from?

A step down transformer?

sPuDd..

[spuddly01]

Also, wear safety glasses while doing it - various items on the PCB have tendancy to go critical and your doctor will have trouble removing them from your soft mushy water sack eyes. Trust me on that.

You could also give the SMPSU board to a local electronics repair shop (if u can find one) and they'll have it up and running quickly.

sPuDd..

[Aussie50]

Thanks for the tips man!, bits of IC case or capacitor are indeed harmful to the eyes!

Main reason why I have not gone further is because I'm not sure if the SMPSU is supposed to be receiving 240Vac or 110 from the main AC board.

A working Fujitsu unit I have is all 110AC, and If I were to apply 240vac to the input of the control SMPSU it would blow the crap outa it!

I'm afraid I'll have to try repairing it whilst attached ot the main AC board untill I find a schematic

[spuddly01]

Looks like the SMPSU for the +5 & +12 is funky. Prob caused by dud secondary electro caps, followed by the IC that runs the SMPSU. I couldn't get a good look but the SMPSU that runs the 5 & 12 looks like it uses a TO-200 case all in one IC. Remove the PCB with the 5 & 12 supply and apply 240Vac to the correct pins - repair it seperate to the main AC board.

sPuDd..

[Aussie50]

it is an all-in-one IC, not sure on the case designation, I'll start with the caps, failing that a new IC may be in order!

[windoes98se]

why does this ac unit have pc bord in it, mine doesnt? coudnt you try bypassing every thin and desighn youre own relay system so you could turn it on using a thermostat?

[Aussie50]

if yours dosn't have a PCB in it chances are its a standard AC compressor with little more than a starting relay/contactor and capacitor.

without the DC inverter these units won't run.

[douro20]

They are "throw-away" items? They are expensive enough!

[Aussie50]

the boards all are, its like main boards in copiers or computers, rarely can you repair them, and its usually obvious stuff like blown caps.

[30GB]

you should have kept the other one for parts but you smashed it lol

[Aussie50]

that one had the same problem, just intermittent.

the one in this vid has already been dismantled but the inverter and compressor are set aside in case I get bored enough to go back to it.

[coolbluelights]

hah I heard the msn noise and I thought it was mine. I have msn too pm me if you want to add me :P

[Aussie50]

cool man!

[diymania]

Its basically the same thing as a vfd, only that ir runs a bldc motor in sensorless mode rather than just spewing out a sine as for a ac induction motor.

[Aussie50]

exactly!

[V8Jagnut]

good find ,that will do it. i still would have set fire to it. i hate electronic crap in a/c units.

[Aussie50]

lol burning electronics is fun, but since inverters are here to stay I may as well teach myself how to fix them. its tricky without a schematic but you can see voltages marked on the PCB, and its the best place to start.