Inverter

[ALONEI]

Hi all

Does anyone have some trubleshooting guide regarding inverters?

Thanks

[NoNickName]

What brand? Inverters are complicated devices. The simple user manual of Siemens inverters is few hundred pages thick.

[Renato RR]

Contact Danfoss.

Renato

[Peter_1]

What exactly is your problem?

[ALONEI]

Hi guys
First thanks for reply
Maybe I didnt explain myself proparly

Im looking for a trubleshooting guide about inverters in aircon units
just like other trubleshooting guids
what to check if......
you know.....something in general

cheers

[Bones]

they are very high voltage, so be carefull if you are poking around one...

unfortuanately getting anything from the manufacter's on these topics is almost non-exist here.

[Peter_1]

Problem is that the inverter is integrated on the main PCB and it is almost impossible to diagnose these.

I know something of electronics but I will never start diagnosing these.

It takes much less time to replace the whole PCB then trying to find out what part on the PCB failed.
If you could find the erratic part, then you also need to find an exact replacement part.
As long as it are resistors, transistors, capacitors, diodes, there is no problem.
But on every PCB, you see microprocessors and these are pre-programmed in the factory with all the logic on it. The smallest voltage spike can burn these and you can't replace these parts.

Another thing I see on nowadays PCB's is that many components are SMD types and they're very small.
To de-solder these an re-solder new ones is really difficult.

And when a part fails on a PCB, many times other parts also have failed but this is almost impossible to measure.

Many times, the compressors are DC fed so these are no common inverters like used in the industry (like Siemens, Danfoss, Mitsubishi, Hitachi,...) where they alter the frequency.
A DC compressor is speed regulated by varying the voltage and this is much easier to perform (also much cheaper) then varying the frequency.

You only can diagnose these systems with a scope, impossible with a standard voltage-meter.

All our voltage-meters are calibrated/constructed for a 50 Hz or 60HZ net and these don't function any longer on different frequencies.

Some manufacturers provide voltage measuring points on the PCB to verify if everything is OK. But if it isn't OK, what then?

I should say, don't try to repair it.
The only thing you can do is measuring the resistances of the compressor windings and compare these to the values given by the manufacturer.
Measure also all the resistance values of all the temperature and pressure probes.
Look if the correct voltage is arriving on the PCB.
Check the fuses on the PCB and that's really all you can do.
And I know that this is frustrating working like this, at least it is for me.
In modern AC, we're degraded to the level of a part replacer, or even better, a PCB replacer.

[ALONEI]

Thanks mate
That makes sense

[Peter_1]

Alonei,
Some time ago there was a post here around with a very handsome book "Service Manual of electronic circuits in Daikin Air Conditioners", teaching the basics of electronics.
I have posted it on http://www.megaupload.com/?d=3EPLJ6ZP
Follow the instructions on the screen.

Johan, if you're reading this post, if there are other interesting books you can share, let me know something.

[justchillin']

You can also now buy an inverter box of tricks from hrp plug in the leads from the comp and connect them on the the box and lights flash to tell you if the comp or the inverter is knakered

[DANIEL ARYEE]

Hi guys
First thanks for reply
Maybe I didnt explain myself proparly

Im looking for a trubleshooting guide about inverters in aircon units
just like other trubleshooting guids
what to check if......
you know.....something in general

cheers

HI BROTHER, I WANT TO INFORM YOU THAT INVERTERS ARE NOT VERY EASY TO TROUBLE SHOOT. IT WILL BE BETTTER YOU REPLACE ANY FAULTY INVERTER YOU SEE, OR SEND THEM TO THE FACTORY FOR REPAIRS. THEY CAN DO BETTER, BECAUSE, THEY HAVE ALL THE INSTRUMENTS AND PARAMETERS TO PUT IT IN ORDER.

DANIEL ARYEE
PORDENONE
ITALY.

[Electrocoolman]

G'day Alonei,
I'm late in replying to this thread as I've only recently joined RE, but have an electronics backgound so might be able to help.
As previously mentioned words of warning - There are HIGH VOLTAGES in all Inverter units ESPECIALLY ON THE CAPACITORS. THESE ARE DANGEROUS AND WILL KILL OR GIVE YOU ONE HELL OF A BELT. Also you can instantly fry the electronics with a flashover in the wrong place. SO IF YOU'RE NOT COMPETENT DON"T MESS WITH IT.

Anyhow...two sorts of units...early ones were AC output , new ones tend to be DC output.
As an example take a SHARP unit: AC ones use a 3 phase compressor. They rectify the mains to produce a DC voltage (if full wave 1.414 x 240vAC = 340vDC). The DC voltage is smoothed and stored by the large capacitors. This is then chopped up by a 'power' transistor module to produce the 3 phase AC. The compressors tend to be 220v 3ph (not 400v as with other 3 ph motors). The AC frequency is varied to control the speed of the compressor - both slower and faster than the normal 50Hz. There are also inductors in the circuit and lots of protection sensors (thermistors).
See wikipedia.org and search power inverter

I have had problems where the diagnostic circuit was indicating a problem with the power module, but the problem was an electrical leakage on the compressor windings to earth.
You will need to see what DC voltage you have on the Caps. Any error codes? Best to get hold of service manual if possible....Most Jap units have good backup.

DC units chop the supply to the compressor which is a permanent magnet motor....see Electric motor#Brushless DC motors on wikipedia.org

Finally another warning....after removing mains power from the unit...go and have a cup of tea and let the voltages disperse....but check those capacitors for volts with your meter before you go delving.
Good luck, Adrian.

NB tried to include urls of sites but wouldn't let me.