Dear Don-Aom
Here is my update for the schematic

R4 is 22K not 220R.

In my case, D1 (1N4749A 24v Zener) was only giving -9v even though D2 tested good in and out of the board.

I replaced D1 and this restored the -24 V line and allowed the communication line to function again and cleared the E6 error.

Regards
Russell

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Dom,

Have a look at this thread ; same unit and PCB, and this guy measured 210 ohms and the resistor is discoloured due to the heat dissipation.

https://www.refrigeration-engineer.com/forums/showthread.php?44126-Airforce-Air-Conditioner-Error-E6

Hi Dom,

Thanks for the feedback.

I did write an amendment to my original post, as I though there was a component designation issue, but it hasn't been posted for some reason.

I was pretty sure that D5 was correct, but on the photo I took, it appears that D1 may be where D5 is shown in the drawing.
Either way, whichever diode is connected directly to Live, is a Zener diode in reverse polarity mode, to create a negative voltage across C5 (which is why C5 is connected with + connected to Neutral, instead of the -).
I performed my repair about a year ago and it is still functioning now.

I will get a better picture of the actual PCB in my unit and correct the drawing as required. R5 does get hot, hence why the colour bands are not what you would expect, based on the actual measure resistance. I did try a 22 ohm resistor in its place, and that DID fry, but that was when the Zener was faulty too.

Give a day or two to sort it out ;)

Regards.
Russ

Having reviewed my drawing, the component designation may be wrong - don't follow these instructions yet. I will check my PCB and provide a phot of the correct component to change. It is definitely a 24V Zener diode, but I need to ensure that the correct one is indicated.

Hi,

First of all, I only speak English - I am in the UK

I have an air conditioner which uses the same internal PCB (GRJ9Q-A) - the system is an inverter type and uses communication on the black wire.
I had E6 - no communication - indicated by the Cooling LED on the indoor unit flashing 6 times, a pause of 2 seconds then flashes 6 times again - no operation of the outdoor unit, just the internal unit fan runs.

It took me a year or two to find the fault.

There is a very crude negative DC power provided by the use of a reverse biased Zener Diode (D5) which has his cathode connected to Live.
The Resistor R4 (220 Ohm Colour code Red-Red-Brown-Black) drops almost 210V, and over time, the colour bands change, but the resistor has maintained its value of 220 Ohms.

The part you need to replace is a 1N4749a 24V Zener Diode (D5). This part will test correctly when a Multi-meter diode test is performed (approximately 0.6-0.7 voltage drop, diode forward biased) while in the PCB, however the negative supply generated when the system is powered on, was only about -9V DC (as seen across electrolytic capacitor C5). the power supply is permanently on, so if your unit is powered on 24/7, even in standby, this zener is working.

I replaced the Zener diode (don't push the legs all the way though the PCB, to allow for some cooling), or, like I did, just snip of the old diode body, then solder the new diode in place, observing the polarity of the cathode (band around the the end of the diode is cathode), but keep the diode legs a bit longer to keep it away from the board.

https://uk.rs-online.com/web/p/zener-diodes/1462264

Once powered on, the LED's on the outdoor unit started flashing indicating communication.

https://drive.google.com/file/d/1p3qd4MIaD2xjEaX8LoLJh3mtisEjkbFG/view?usp=sharing

see these YouTube pages too, as they cover the model I have, which uses the same PCB's as the DeLonghi unit - made by GREE in China

https://www.youtube.com/watch?v=Q3KDFm8i51Y&lc=UgxP5Ou0t0MGXYH_oyt4AaABAg.9dvANix5vsk9e24eNwQOFI
https://www.youtube.com/watch?v=vQPUCMFOMcY

Google Translation :

Bonjour.
Tout d'abord, je ne parle que l'anglais je suis au Royaume-Uni

J'ai un climatiseur qui utilise le même circuit imprimé interne (GRJ9Q-A) - le système est de type onduleur et utilise la communication sur le fil noir.
J'ai eu E6 - pas de communication - indiqué par le voyant de refroidissement de l'unité intérieure qui clignote 6 fois, une pause de 2 secondes puis clignote à nouveau 6 fois - pas de fonctionnement de l'unité extérieure, seul le ventilateur de l'unité interne fonctionne.

Il m'a fallu un an ou deux pour trouver la panne.

Il existe une alimentation CC négative très grossière fournie par l'utilisation d'une diode Zener polarisée en inverse (D5) dont la cathode est connectée à Live.
La résistance R4 (code couleur 220 Ohms rouge-rouge-marron-noir) chute de près de 210V, et avec le temps, les bandes de couleur changent, mais la résistance a conservé sa valeur de 220 Ohms.

La pièce que vous devez remplacer est une diode Zener 1N4749a 24V (D5). Cette partie sera testée correctement lorsqu'un test de diode multimètre est effectué (chute de tension d'environ 0,6 à 0,7, diode polarisée en direct) dans le circuit imprimé, mais l'alimentation négative générée lorsque le système est sous tension n'était que d'environ -9 V CC ( vu à travers le condensateur électrolytique C5). l'alimentation est allumée en permanence, donc si votre appareil est alimenté 24h/24, même en veille, ce zener fonctionne.

J'ai remplacé la diode Zener (ne poussez pas les jambes complètement à travers le PCB, pour permettre un certain refroidissement), ou, comme je l'ai fait, coupez simplement l'ancien corps de diode, puis soudez la nouvelle diode en place, en observant le polarité de la cathode (la bande autour de l'extrémité de la diode est la cathode), mais gardez les pattes de la diode un peu plus longtemps pour l'éloigner de la carte.

https://uk.rs-online.com/web/p/zener-diodes/1462264
Une fois sous tension, les LED de l'unité extérieure ont commencé à clignoter pour indiquer la communication.
https://drive.google.com/file/d/1p3qd4MIaD2xjEaX8LoLJh3mtisEjkbFG/view?usp=sharing

voir aussi ces pages YouTube, car elles couvrent le modèle que j'ai, qui utilise les mêmes circuits imprimés que l'unité DeLonghi - fabriquée par GREE en Chine

https://www.youtube.com/watch?v=Q3KDFm8i51Y&lc=UgxP5Ou0t0MGXYH_oyt4AaABAg.9dvANix5vsk9e24eNwQOFI
https://www.youtube.com/watch?v=vQPUCMFOMcY

airforce inveter communication 24v power supply 29 may 2021 15 15 53.pdf

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