Hanny 12V2 power supply repair

[csabex]

Hello everyone,

I just tried to repair this 12V Hanny PS, but with no luck I replaced the CR6238T integrated circuit, because it seemed that the problem is caused by this ic. After replacement still no power at all on the 12V side... Maybe the filter choke would be the problem? Caps are ok, they keep the 320 V as i measured and i felt because they didn't apply a resistor to the circuit and when i dismounted i touched somehow the caps output and i felt that power
How could i test the filter choke ? I should take it out from circuit, but how can be tested ? Or somebody could help me to buy somewhere a new one or a similar one that has this sizes? Thank you in advance.

[budm]

Re: Hanny 12V2 power supply repair

Did you test that small starup/running cap in the primary side?
The current sensing resistor connected to the CS pin and the primary circuit GND is OK?
We also need the DCV reading between the GND pin against all other pins to find out what they are.

[budm]

Re: Hanny 12V2 power supply repair

CR6238 spec sheet.

[csabex]

Re: Hanny 12V2 power supply repair

First of all thanks for the help The small startup cap, the 10 uF/50V i changed to a new one and the resistor (the R3 also) also to a new one, that's why it's size it is a little bigger then the other ones in the circuit. At the voltages reading do you mean the CR6238 pin voltages? The voltages of the VDD, COMP, INV and CS ? At this point the drain pins (5,6) doesn't matter, no? Or should i read the voltages there also?

[budm]

Re: Hanny 12V2 power supply repair

First of all thanks for the help The small startup cap, the 10 uF/50V i changed to a new one and the resistor (the R3 also) also to a new one, that's why it's size it is a little bigger then the other ones in the circuit. At the voltages reading do you mean the CR6238 pin voltages? The voltages of the VDD, COMP, INV and CS ? At this point the drain pins (5,6) doesn't matter, no? Or should i read the voltages there also?

1) Show us all the Voltage of all the pins with ref to the GND pin.

2) Was R3 bad? What was the reason for replacing R3.

3) Please always provide what you have done to the board so we do not have to make the guess what parts you have or have not replaced.

[csabex]

Re: Hanny 12V2 power supply repair

The R3 wasn't bad, i just decided if i go to the electronics shop for the capacitor, then i buy these 2 resistors, because on some other forum on the net i had read about the power supply failure because of the resistors problem. What i have changed until now it is R2, R3 then the 10 uF capacitor and finaly the CR6238 ic. On the attached pictures you can see the voltages. It is weird that on the pin nr 3 and 4 there is no voltage at all... In the datasheet it is written that it should be feedback and an input current or do i miss something? Another thing: On the pin 2 the voltage increases above 400V and after that suddenly drops and rises again. I suppose that this is normal because on the datasheet says that this is a kind of loop current, but what for? Can you confirm that i suppose correctly, because i have to admit that i am really an "intermediate beginner" in the electronics Thank you.

[budm]

Re: Hanny 12V2 power supply repair

I doubt that R2 and R3 are bad. What are the value of R2 and R3? the one resistor that is connected to the CS pin of the IC will be very low resistance, usually <1 Ohms, so we need to verify that you are using the correct resistors.
Since VDD pin1 does not have much Voltage at all, I suspect that the two 820K resistors which are connected in series (one end is connected to pin 1 VDD, another end is connected the (+) leg of the main filter cap) may have gone up in resistance so the VDD pin is not getting enough kick start Voltage to run. You need to verify the resistance of those two resistors.

[csabex]

Re: Hanny 12V2 power supply repair

The R2 and R3 it is ok for sure. The resistor connected to the CS pin value it is indeed <1 Ohm, more exactly is 0,970. Well, you were right about the 820k resistors that are connected in series, because one of them it is ok and the other one doesn't show any value, i believe the metal coil inside or whatever it is, it's broken. It was to late and the electronics shop it is closed already and home i searched a lot, but i haven't find any I know why i was missed this, because i measured only one resistor and that was ok, so i think that the other one i didn't measure, because i supposed that is ok, but it isn't at all Thank you for the tip and basically for the remote repair I believe that small resistor will be the problem, the one that you suggested.

[petehall347]

Re: Hanny 12V2 power supply repair

replace both resistors .

[budm]

Re: Hanny 12V2 power supply repair

replace both resistors .

+10.

[CapLeaker]

Re: Hanny 12V2 power supply repair

with resistors one never really knows. I had a starter resistor, that measured good while power off. Once I applied power the resistance changed (got rapidly higher) so the PSU turned quickly off. On a different PSU a small SMD resistor was only off by 7 Ohms and the thing wouldn't start.

[budm]

Re: Hanny 12V2 power supply repair

Follow-up?

[csabex]

Re: Hanny 12V2 power supply repair

Sorry for the late reply, but i wasn't home 2 days and before i have traveled quickly bought two resistors and replaced both of them, and the miracle has happen ! It works! Well, i have measured only 11,3V but that 0,7 V doesn't really matter, but if you suspect the reason of this small difference then just let me know and i will check. Thanks or everyone, but especially to budm user for helping me