12V 10A CCTV camera system power supply pulsating

[CapLeaker]

Re: 12V 10A CCTV camera system power supply pulsating

Make sure the transformer windings didn’t brake off from the legs.

[rddube]

Re: 12V 10A CCTV camera system power supply pulsating

So removed transformer, checked continuity for all the legs, redid the solder joints just in case, re-checked continuity between windings and legs. Reinstalled, tested and same result.

[harp]

Re: 12V 10A CCTV camera system power supply pulsating

Found working voltage on ic OB2269

pin1: 0.0v
pin2: 1.5v
pin3: 1.3v <--- !?
pin4: 2.0v
pin5: 5.6v
pin6: 0.0v
pin7: 11.9v
pin8: 0.01v

https://www.youtube.com/watch?v=3p1xYX7B9sY



Compare to your psu (with C4)

Pin 1: GND
Pin 2: .1V to .3V oscillating
Pin 3: 16V to 19V oscillating
Pin 4: 0V to 1.3V jumping around sometimes to 3.2V
Pin 5: same as pin 4
Pin 6: 0V, sometimes shows .1V or .2V then 0V
Pin 7: Oscillating between 11V and 15V
Pin 8: .001V


If you disconnect psu from mains, and remove secondary output diode and then feed adjustable 10-14v to output terminals, so that tl431 circuit is working, you can monitor opto transistor resistance (primary side) and confirm that switch on at 12v point. Set on 12v with trimpot 1K.

If this is ok... so 12v connected is to output without diode and optocoupler working.
When you connected psu in mains like in that condition, what is voltage on each ic pin, is they still pulsating or not?

If they are still pulsating, and energy on secondary is independed, regulated and calm, that prove that problem is on primary side.

On primary is generaly main windings and aux... and then we must find a way to separate one from another... maybe is transformer windings problem, if you have ringing tester you can confirm that.

[stj]

Re: 12V 10A CCTV camera system power supply pulsating

looked at the datasheet.
pin3 is not getting power - if it follows the example then it's just a resistor or 2 to the rectified mains - check that.

[rddube]

Re: 12V 10A CCTV camera system power supply pulsating

Found working voltage on ic OB2269

pin1: 0.0v
pin2: 1.5v
pin3: 1.3v <--- !?
pin4: 2.0v
pin5: 5.6v
pin6: 0.0v
pin7: 11.9v
pin8: 0.01v

https://www.youtube.com/watch?v=3p1xYX7B9sY



Compare to your psu (with C4)

Pin 1: GND
Pin 2: .1V to .3V oscillating
Pin 3: 16V to 19V oscillating
Pin 4: 0V to 1.3V jumping around sometimes to 3.2V
Pin 5: same as pin 4
Pin 6: 0V, sometimes shows .1V or .2V then 0V
Pin 7: Oscillating between 11V and 15V
Pin 8: .001V


If you disconnect psu from mains, and remove secondary output diode and then feed adjustable 10-14v to output terminals, so that tl431 circuit is working, you can monitor opto transistor resistance (primary side) and confirm that switch on at 12v point. Set on 12v with trimpot 1K.

If this is ok... so 12v connected is to output without diode and optocoupler working.
When you connected psu in mains like in that condition, what is voltage on each ic pin, is they still pulsating or not?

If they are still pulsating, and energy on secondary is independed, regulated and calm, that prove that problem is on primary side.

On primary is generaly main windings and aux... and then we must find a way to separate one from another... maybe is transformer windings problem, if you have ringing tester you can confirm that.

Ok, so I'll try to do this and will report back.

[rddube]

Re: 12V 10A CCTV camera system power supply pulsating

looked at the datasheet.
pin3 is not getting power - if it follows the example then it's just a resistor or 2 to the rectified mains - check that.

Not sure I understand, pin 3 is getting from 16V to 19V coming from those 2 large caps, going through the 1.5M ohm resistor?

[rddube]

Re: 12V 10A CCTV camera system power supply pulsating

Found working voltage on ic OB2269



If you disconnect psu from mains, and remove secondary output diode and then feed adjustable 10-14v to output terminals, so that tl431 circuit is working, you can monitor opto transistor resistance (primary side) and confirm that switch on at 12v point. Set on 12v with trimpot 1K.

Hi again, to measure resistance on the opto (primary side), I will have to do it with the secondary energized and I'm not sure it is a good idea to take resistance readings on an energized circuit, because to measure resistance, the multimeter sends a small amount of voltage to calculate the resistance. Anyone?

[RukyCon]

Re: 12V 10A CCTV camera system power supply pulsating

The two sides of an opto are electrically isolated from each other, this is necessary to ensure that the secondary side of the PSU remains isolated from mains, but besides that, i don't think i've ever had any issues with measuring components in-circuit while the circuit was "live", just as long as you don't short anything out.

As for the PSU itself, was D2 ever properly tested? I say this because i've had diodes test fine when tested with something like a multimeter (which may only be passing <10ma though the diode) only for said diode to 'fail' under any real load, so sometimes it may be worth testing said diode with a current adjustable power supply. Thought i'd throw my 2 cents in, just in case they help.

[stj]

Re: 12V 10A CCTV camera system power supply pulsating

the first problem is pin3 not getting power
if the main caps are stable at about 160v or 340v if it's a doubler, then you need to check the traces and resistor to pin3

[harp]

Re: 12V 10A CCTV camera system power supply pulsating

Hi again, to measure resistance on the opto (primary side), I will have to do it with the secondary energized and I'm not sure it is a good idea to take resistance readings on an energized circuit, because to measure resistance, the multimeter sends a small amount of voltage to calculate the resistance. Anyone?

You are right, but idea is that you measure resistance on not-energized part of circuit on optocoupler. Optocoupler is device with two isolated circuit. Pin 1 and 2 (LED) is energised in this kind of test, but pin 3 and 4 (optotransistor) are electricaly, physicaly and galvanic isolated from LED side. Only light pass to other side. There not be any voltage, you can check first with voltmeter if doubt.
Just DO NOT mismatch sides (like usual ) and measure resistance of powered LED... be careful, attention.

[rddube]

Re: 12V 10A CCTV camera system power supply pulsating

The two sides of an opto are electrically isolated from each other, this is necessary to ensure that the secondary side of the PSU remains isolated from mains, but besides that, i don't think i've ever had any issues with measuring components in-circuit while the circuit was "live", just as long as you don't short anything out.

As for the PSU itself, was D2 ever properly tested? I say this because i've had diodes test fine when tested with something like a multimeter (which may only be passing <10ma though the diode) only for said diode to 'fail' under any real load, so sometimes it may be worth testing said diode with a current adjustable power supply. Thought i'd throw my 2 cents in, just in case they help.

Ok, thanks for the advice. As for D2, I tried another same diode and had the same results, so we're still trying to identify the culprit

[rddube]

Re: 12V 10A CCTV camera system power supply pulsating

You are right, but idea is that you measure resistance on not-energized part of circuit on optocoupler. Optocoupler is device with two isolated circuit. Pin 1 and 2 (LED) is energised in this kind of test, but pin 3 and 4 (optotransistor) are electricaly, physicaly and galvanic isolated from LED side. Only light pass to other side. There not be any voltage, you can check first with voltmeter if doubt.
Just DO NOT mismatch sides (like usual ) and measure resistance of powered LED... be careful, attention.

Ok, got ya. Will report back.

[rddube]

Re: 12V 10A CCTV camera system power supply pulsating

the first problem is pin3 not getting power
if the main caps are stable at about 160v or 340v if it's a doubler, then you need to check the traces and resistor to pin3

Do you really mean pin 3? The main cap is getting 160V and on one end of R3 getting 163V, while the other end of R3 (1.5M ohm) going to pin 3 is oscillating between 16V to 19V.

[RukyCon]

Re: 12V 10A CCTV camera system power supply pulsating

Ok, thanks for the advice. As for D2, I tried another same diode and had the same results, so we're still trying to identify the culprit

Okay, wasn't aware of that, but good to know. One thing i would probably try (if i had nothing better to try) is maybe swapping C4 with a slightly larger capacitor (say between 22 - 47uf). Worse case i could see is that it makes the PSU slightly slower to start up, though i haven't dealt with this exact controller before, and thus you may want to wait for a second opinion before trying it just to prevent anything from going south.

BTW, for curiosity's sake, what brand are those caps on the PSU?

[stj]

Re: 12V 10A CCTV camera system power supply pulsating

Do you really mean pin 3? The main cap is getting 160V and on one end of R3 getting 163V, while the other end of R3 (1.5M ohm) going to pin 3 is oscillating between 16V to 19V.

well thats good - i wonder why it's oscillating.
maybe the chip is trying to drive a short circuit

[rddube]

Re: 12V 10A CCTV camera system power supply pulsating

BTW, for curiosity's sake, what brand are those caps on the PSU?

The brand is Cap-Top (Low ESR) - never heard of them, but I did take all of them out and checked them with my component tester and they all tested good. C4 I changed for an Elite cap that measure 10.2 uf ESR .04.

[CapLeaker]

Re: 12V 10A CCTV camera system power supply pulsating

I am getting a feeling something is high resistance or open.

[petehall347]

Re: 12V 10A CCTV camera system power supply pulsating

post a nice list of present voltages at the ic to compare with what they should be .. lets see if its doing what it is told or if doing as intended with this fault condition .

[rddube]

Re: 12V 10A CCTV camera system power supply pulsating

Found working voltage on ic OB2269


If you disconnect psu from mains, and remove secondary output diode and then feed adjustable 10-14v to output terminals, so that tl431 circuit is working, you can monitor opto transistor resistance (primary side) and confirm that switch on at 12v point. Set on 12v with trimpot 1K.

If this is ok... so 12v connected is to output without diode and optocoupler working.
When you connected psu in mains like in that condition, what is voltage on each ic pin, is they still pulsating or not?

If they are still pulsating, and energy on secondary is independed, regulated and calm, that prove that problem is on primary side.

On primary is generaly main windings and aux... and then we must find a way to separate one from another... maybe is transformer windings problem, if you have ringing tester you can confirm that.

Ok, so did the above test - removed secondary output diode, injected 12V on the output and took measurements of optocoupler resistance primary side:

No voltage applied (power off) - 3.191K ohms
10V applied - 1.086Mohms
12V applied - 1.086Mohms
13.3V applied 1.088Mohms

Took out the voltage from the output, left the secondary diode out and plugged into mains, readings on the chip:

Pin 1 - Gnd
Pin 2 - .03V - 5V jumping around erratically
Pin 3 - .14V to 19V jumping around erratically
Pin 4 - 0V - 1.9V jumping around erratically
Pin 5 - .2V to 4.6V jumping around erratically
Pin 7 - 11V - 22V jumping around erratically
Pin 8 - .01V - .28V jumping around erratically

Will reinstall the ouput diode and do the tests that Petehall437 just asked.

[stj]

Re: 12V 10A CCTV camera system power supply pulsating

pin3 should not be eratic - it should be a stable voltage from that resistor-dropped mains