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Old 01-30-2019, 06:18 AM   #1
Hauke
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Default Delta ADP-310AF No Power and frequently chirping

Hey guys,
I have got this iMac 2011 power supply which doesn't provide any voltage. It is repeatedly chirping about every 2 seconds.

I already checked the most common parts but did not find any bad component.

The weird thing is, as I was checking the PSU with my oscilloscope, the PSU suddenly started! The chirping was now continuous, but I got 12V on the secondary side.
This brings me to the idea, that this problem has to be with some passive component? I was told, that the iMac won't start anymore, but very rarely it started.

Does anyone know this PSU and has experiences with it?
I think I would start troubleshooting the start circuit next, or what would you try?

Thanks.
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Old 01-30-2019, 09:49 AM   #2
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Default Re: Delta ADP-310AF No Power and frequently chirping

It could be one of the small electrolytics, usually in the primary, 1-22µf 50 volt types, they look good but go open.
Since you have a scope, check what waveform you have on them, but you will need an isolation transformer to check the primary, if you don't use an isolation transformer, the scope ground will short the power supply.
If the cap is for filtering, you should not see any signifcant ripple, if the cap is open you will see a large ripple.

Last edited by R_J; 01-30-2019 at 09:53 AM..
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Old 01-30-2019, 11:28 AM   #3
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Default Re: Delta ADP-310AF No Power and frequently chirping

Thanks for your answer. I checked the waveform at the electrolytic capacitors.
I get a fast rising edge when the psu "chirps" which drops like a normal capacitor discharging curve until the next "chirp" charges the capacitor again.
I search for any other ripple now.

After I accidentally blew up my first scope I built myself an isolation transformer
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Old 01-30-2019, 12:56 PM   #4
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Default Re: Delta ADP-310AF No Power and frequently chirping

Quote:
Originally Posted by Hauke View Post
Thanks for your answer. I checked the waveform at the electrolytic capacitors.
I get a fast rising edge when the psu "chirps" which drops like a normal capacitor discharging curve until the next "chirp" charges the capacitor again.
I search for any other ripple now.
...
Sounds like one of those caps has gone high ESR. It charges enough to let the PWM start, but can't provide enough voltage for the PWM to keep operating.
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Old 01-30-2019, 01:28 PM   #5
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Default Re: Delta ADP-310AF No Power and frequently chirping

Ok, I will desolder the caps and check their current leakage. What would be an acceptable value?

The supply voltage at the 2 ICs on the primary side is bouncing too. Its between 6V and 14V.

The rectified supply voltage is relatively stable between 360V and 370V
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Old 01-30-2019, 02:26 PM   #6
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Default Re: Delta ADP-310AF No Power and frequently chirping

at 8years old, i would just replace anything under 470uf without even checking them.
small body caps have a relativly low lifespan.
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Old 01-31-2019, 09:54 AM   #7
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Default Re: Delta ADP-310AF No Power and frequently chirping

I replaced the electrolytic caps, but the problem is still the same.
I found out, that the DC voltage directly at the rectifier breaks down at the moment of "chirping". When the psu randomly starts working and I can hear the continuous noise, the voltage at the rectifier is constant.

Has anyone an idea what the coil in the middle left is for? I think it is switched by the transistor in the middle and this is where the noise comes from.
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Old 01-31-2019, 10:03 AM   #8
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Default Re: Delta ADP-310AF No Power and frequently chirping

which rectifier, the mains input, or the output?
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Old 01-31-2019, 10:45 AM   #9
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Default Re: Delta ADP-310AF No Power and frequently chirping

At the mains input. I placed a 220µF cap in parallel so that the voltage doesn't drop that much. I think the noise got more silent, but it did not solve the problem.
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Old 01-31-2019, 11:14 AM   #10
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Default Re: Delta ADP-310AF No Power and frequently chirping

remove and test the main cap - it could be trashed by a PFC circuit.
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Old 01-31-2019, 05:13 PM   #11
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Default Re: Delta ADP-310AF No Power and frequently chirping

The two main caps seem to be ok.
Now the psu doesn't try to start at all. I don't really know why.
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Old 01-31-2019, 11:42 PM   #12
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Default Re: Delta ADP-310AF No Power and frequently chirping

With the primary caps checked out, I would suspect bad solder joints next.

Try reflowing/re-soldering all joints on the large parts - i.e. transformers, large transistors and rectifiers, and such. If the PSU and/or PC it was in was ever dropped, you might also have a broken trace somewhere, again, on one of the large components. It could be very hard to see, so it may help to try to push/exert a bit of force with your fingers on the large parts to see if any of the solder joints and/or their traces move.

Quote:
Originally Posted by Hauke
Has anyone an idea what the coil in the middle left is for? I think it is switched by the transistor in the middle and this is where the noise comes from.
That's the APFC inductor, and the transistor that is connected to it on one side and primary ground on the other side, is the APFC MOSFET.

Speaking of which... check the thermistor/NTC/inrush current limiter on the input. I can't see it on your pictures, but it should be in there somewhere - typically after the fuse but no later than the APFC diode or inductor.

Last edited by momaka; 01-31-2019 at 11:47 PM..
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Old 03-14-2022, 10:05 AM   #13
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Default Re: Delta ADP-310AF No Power and frequently chirping

Hola. gusto en saludarles.

Se que este post es antiguo, pero me llegó al taller está fuente de poder. Modelo: ADP-310 AF B. Marca DELTA.

Al conectarla a la linea de 110vac, en el conector es de 16 Pines. tengo: Pin 4 = 12vdc y pin 6 = 3.8vdc aprox. En los pines del secundario.

Sin embargo, he buscado por internet y no consigo el Pin-Out exacto para saber cual es el pin de PS-ON. Para poder encenderla sin la PC.

La PC iMAC A1311. Cuando se conecta la fuente de poder a la línea de 110vac. apenas enciende el led 1 de diagnostico y se apaga, sin embargo los voltajes de la fuente antes citados se mantienen activos.

Sospecho problema de board, pero me intriga probar la fuente sin la placa.

Adjunto fotos.

Gracias de antemano a todos.

Hello, nice to greet you.

I know this post is old, but I got this power supply in the workshop. Model: ADP-310 AF B. DELTA brand.

When connected to the 110vac line, in the connector is 16 pins. I have: Pin 4 = 12vdc and pin 6 = 3.8vdc approx. on the pins of the secondary.

However, I have searched the internet and I can't get the exact Pin-Out to know which is the PS-ON pin. So that I can power it up without the PC.

The iMAC A1311 PC. When the power supply is connected to the 110vac. line, it barely lights the diagnostic led 1 and turns off, however the aforementioned power supply voltages remain active.

I suspect board problem, but I am intrigued to test the power supply without the board.

Attached are pictures.

Thanks in advance to all.
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Old 03-16-2022, 04:26 AM   #14
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Default Re: Delta ADP-310AF No Power and frequently chirping

I believe yours is A1312, which is the 27" PSU.


The attached picture maybe of help.
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Old 03-16-2022, 04:51 AM   #15
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Default Re: Delta ADP-310AF No Power and frequently chirping

Thank you very much Protocold.

I had seen that image before but since my source varies on the ICs below the connectors, I didn't dare to use that schematic to make the ground jumper.

I managed to find the schematic on the board and confirmed that pin 6 of the PSU is indeed the PS On pin. I managed to turn on the power supply, it works fine, the problem is in the motherboard.

Thank you very much for your time and help.

Muchas Gracias Protocold.

Yo había visto esa imagen antes pero como mi fuente varia en los circuitos integrados que estan abajo de los conectores, no me animé a usar ese esquema para hacer el puente a tierra.

Logré dar con el esquema de la placa y confirmé que efectivamente el pin 6 de la PSU es el de PS On. Logré encender la fuente, la misma trabaja bien, el problema está en la placa madre.

Muchas gracias por su tiempo y ayuda.
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