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Old 10-28-2021, 11:45 AM   #1
Xristakis795
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Default problem with ic ma8910 in power supply of aircondition

power supply from air conditioning short-circuits the integrated MA8910 I have checked everything more specifically I changed the varistor the adaptation coil was burnt and I put one of the TV power supply
the four diodes were short-circuited, I changed them, all the short circuits I had were gone
I have changed it twice and it burns again and the diodes of the rectifier bridge burn the safety I am very afraid that the ones I bought may not be of good quality
does anyone know how this complete works because from the manual I find I do not get an edge
which in your opinion may be the reason that my short circuit is caused by the low voltage transformer?
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Old 10-29-2021, 04:40 AM   #2
sam_sam_sam
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Default Re: problem with ic ma8910 in power supply of aircondition

Can you please tell me what this devices that this board controls on this air conditioner pictures of what it controls would be nice so I can get a mental picture of what it suppose to be doing
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9 PC LCD Monitor
6 LCD Flat Screen TV
30 Desk Top Switching Power Supply
10 Battery Charger Switching Power Supply for Power Tool
6 18v Lithium Battery Power Boards for Tool Battery Packs
1 XBox 360 Switching Power Supply and M Board
25 Servo Drives 220/460 3 Phase
6 De-soldering Station Switching Power Supply 1 Power Supply
1 Dell Mother Board
15 Computer Power Supply
1 HP Printer Supply & Control Board * lighting finished it *


These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%

1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later )
2 Hem Saw Computer Stack Board

All of these had CAPs POOF
All of the mosfet that are taken out by bad caps
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Old 10-29-2021, 02:26 PM   #3
Xristakis795
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Default Re: problem with ic ma8910 in power supply of aircondition

Quote:
Originally Posted by sam_sam_sam View Post
Can you please tell me what this devices that this board controls on this air conditioner pictures of what it controls would be nice so I can get a mental picture of what it suppose to be doing
sir this board is the indoor unit of a dalkin air conditioner
I quote you two additional photos in one is the same I just show you with arrows now the parts I changed
and in the other a schematic that I found without explanation of the operation of the complete MA 8910
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Old 10-30-2021, 09:39 AM   #4
sam_sam_sam
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Default Re: problem with ic ma8910 in power supply of aircondition

Is it this part number

https://www.jotrin.com/product/parts/MA8920

If it is or something similar to it and you have changed it you might have an issue with the switching power transformer but you would have to have a ring tester for transformer to see if it is shorted you can not use an ohms meter for this

However it is rare that a switching power supply transformer goes bad but it does happen

Or you have a short on the secondary side of this switching power supply

I would also check the capacitors for shorts as highly unlikely that you would have one that would do this but if it is a paper wound type it is possible

Have you checked the optic sensors on the top right side of this board to see if they are working correctly or not you would have to test them off the board

This device is very private and there is no information about it other than this little bit of information that was able to find

Last edited by sam_sam_sam; 10-30-2021 at 10:02 AM..
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Old 10-30-2021, 01:32 PM   #5
Xristakis795
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Default Re: problem with ic ma8910 in power supply of aircondition

I agree with you sir
I also suspect the switching transformer but unfortunately I do not have a ring tester to confirm it oh
I'm thinking of detaching the transformer and trying it out
as for the optics you told me to check I have not done it yet I will see
question did you download the MA 8920 manual? with function explanation; because i can not download it for some reason i ask
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Old 10-30-2021, 02:06 PM   #6
sam_sam_sam
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Default Re: problem with ic ma8910 in power supply of aircondition

No it will not let you/you have to register and I not going to that because I do not think that you would get any more information than I what sent you the link to that give you a brief over view of what this device is
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Old 10-30-2021, 02:28 PM   #7
Xristakis795
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Default Re: problem with ic ma8910 in power supply of aircondition

thanks
i think what i said before was a bit stupid;
it makes sense to try to detach the transformer I think not because no current will pass through the fet of MA 8910 do you agree Mr. Sam?
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Old 10-30-2021, 07:00 PM   #8
sam_sam_sam
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Default Re: problem with ic ma8910 in power supply of aircondition

If you can figure out which winding is the primary side of the transformer you could hook up a incandescent light to those pins and see if will light it up ( it might be briefly or in pluses ) but the ic chip will be looking for a fed back so I am not sure that this will work or not

Now what you could do is put an incandescent light bulb instead of the fuse and see how bright the light bulb gets if it bright then you have some sort of short some where

But this where if you think that the switching transformer is the problem and you have a ring tester it would tell you if you have a short on it I seen this before on some of the switching power supply board I have worked on before in the past when the fuse has blown that is one of the first thing I check

Last edited by sam_sam_sam; 10-30-2021 at 07:08 PM..
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Old 10-31-2021, 10:34 AM   #9
Xristakis795
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Default Re: problem with ic ma8910 in power supply of aircondition

Thank you very much for the important advice you give me, Mr. Sam
one last thing I would like to ask to be sure
a. in the position of the primary transformer's how many watt bulbs should I put?
and
b in the fuse position which is 3.15 amps how many watts again lamp should i use?
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Old 10-31-2021, 10:44 AM   #10
sam_sam_sam
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Default Re: problem with ic ma8910 in power supply of aircondition

I would do this first

I would probably use a incandescent light bulb from 40 to 300 watt if you are putting it in place of the fuse then I would start off with 40 watt and see how bright the light bulb is first but I would caution you to be careful going more than 100 watt because what ever the issue is it might let out the factory smoke the more wattage bulb you use

I would do this second

You can do this and like I said earlier I do not know if this would work because ic chip needs the feedback from the secondary winding you can try it I do know if it will do anything or not the most I think it might do is flash and maybe keep flashing but not sure I personally have not tried to do this because I have a ring tester

Last edited by sam_sam_sam; 10-31-2021 at 10:53 AM..
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Old 11-09-2021, 03:56 AM   #11
Xristakis795
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Default Re: problem with ic ma8910 in power supply of aircondition

Mr. Sam I found a component that is in series with the + of the electrolytic capacitor ntc thermistor 5d-11 and I read that it is to suppress the current at the start which is peeled on one side not cracked and shows me 8 ohm you know if it is normal of this resistance;
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Old 11-09-2021, 05:29 PM   #12
sam_sam_sam
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Default Re: problem with ic ma8910 in power supply of aircondition

Please post the part number of the device in question
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Old 11-09-2021, 05:57 PM   #13
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Default Re: problem with ic ma8910 in power supply of aircondition

The 5d-11 should check 5Ω, 8Ω should still be ok, it is a ntc so the resistance will decrease with current. The transformer is the last thing I would suspect.
If you can provide large clear pictures of both the top and bottom of the board, we may be able to trace the circuit better.

Last edited by R_J; 11-09-2021 at 06:08 PM..
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Old 11-10-2021, 04:12 AM   #14
Xristakis795
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Default Re: problem with ic ma8910 in power supply of aircondition

thanks for the answers and the helps
because the 8910s I had bought burned and I have to buy them from China, they will be too late to come, I will get a new board
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