12V 10A CCTV camera system power supply pulsating

[rddube]

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

Also, after taking the readings, I took out the mosfet on the primary side and here's a photo, and the readings it gives me in my component tester (there are 3 screens).

[rddube]

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

before do anithing, do exactly one more time very same measurement, write data to compare.


my analisy

point A is far end of +, our reference of this test
probing ground
point D is maximum 166.6 through jumper wire
point F slightly lower 166.1
pin#1 dramaticaly lower 164.2, on sam plane with F, were is 2v lost?!?

point C near cap 165.3... something is pulling it down (mosfet try switch)
point B 164.3 (27.2mV ripple present)
point E 165.2 no ripple! there is only a 000 resistor between point E and B.


So, check what is going on between point F and pin#1, also point B and E, where is lost 1v and ripple? Check 000 resistor, it is not posible it is ok.
Is this make sense to you?


Your board may suffer of circular crack arround solder point, and when you measure this, you push it with probe and connect again with track, and all seems ok, but it is intermitten.

Ok, redid the readings with my other multimeter, and this is what I get (see photo).

[rddube]

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

Your board may suffer of circular crack arround solder point, and when you measure this, you push it with probe and connect again with track, and all seems ok, but it is intermitten.

Very funny you say this Harp, as when I initially took out the board on this PSU, I noticed a cold solder joint on the R9 leg shown in the picture. At first it looked like a cold solder, but now that you mention this (circular crack), I think that's what it was! And the board is very fragile in that area as I mentionned, around the legs of the IC using my Hakko desoldering tool, it removed some of the traces, so I think I should almost do an Xray examination!

[harp]

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

before do anithing, do exactly one more time very same measurement, write data to compare.


my analisy

point A is far end of +, our reference of this test
probing ground
point D is maximum 166.6 through jumper wire
point F slightly lower 166.1
pin#1 dramaticaly lower 164.2, on sam plane with F, were is 2v lost?!?

point C near cap 165.3... something is pulling it down (mosfet try switch)
point B 164.3 (27.2mV ripple present)
point E 165.2 no ripple! there is only a 000 resistor between point E and B.


So, check what is going on between point F and pin#1, also point B and E, where is lost 1v and ripple? Check 000 resistor, it is not posible it is ok.
Is this make sense to you?


Your board may suffer of circular crack arround solder point, and when you measure this, you push it with probe and connect again with track, and all seems ok, but it is intermitten.

[CapLeaker]

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

Running out of options. Only thing left to do is to take the mosfet out of the primary, plug the psu in and redo the voltage measurements at the pins of the PWM.

[rddube]

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

OK, here are the measurements with 100k resistor installed:



DC V AC mv
A and B 164.3 27.2 jumping around
A and C 165.3 0.000
A and D 166.6 0.000
A and E 165.2 0.000
A and F 166.1 0.000
A and IC Pin#1 (gnd) 164.2 0.000

Might be cleared and better aligned on the photo.

[rddube]

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

Look at post #16.
Don't get fixated on the jumping voltage on the cap. The problem isn't there, it's just a result. The PWM is either in UVLO or OVP. I did notice that one can buy this PWM with or without OVP protection for some reason or another.

Ok, I get you. The interesting thing is that although I did buy some new chips, I did reinstall the original at some point and was getting the same result. Did check the markings on the chips and attached is a photo - they do not have the exact markings - the original has OB in front of the chip number? It is the one on the right in the photo.

[CapLeaker]

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

Ok, I see. But why is it giving me a steady voltage on the main caps (163V), and when I remove C4, I get a steady voltage of approx 18V on pin 3. Whenever I reinstall C4, everything starts to jump around?? R10 (1.5Mohm) is what cuts the 163V down to 18V, and it is steady when C4 is out and bounces when C4 is installed....

Look at post #16.
Don't get fixated on the jumping voltage on the cap. The problem isn't there, it's just a result. The PWM is either in UVLO or OVP. I did notice that one can buy this PWM with or without OVP protection for some reason or another.

[rddube]

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

Ok, will rinstall 100K and report back

[harp]

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

I think that with 100k is better chance to even start working because of lower frequency. Once you get it worked, a 56k is good, max 51k. For me, 27k is not option at all.

[rddube]

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

I will love to know answer also...
Lost in space... try measure voltage (with decimal point max resolution) between point A and B, A and C, A and D, A and E, A and F, and A and IC Pin#1 (gnd) in DC and AC (mV) settings... in DC settings it has to be about 163V, but I am interesting if after decimal point has any changed along the track... maybe some information arrive... hunting dark shaddow...

Ok, should I reinstall the 100k resistor or leave the 56K or return to the 28k resistor before taking readings?

[petehall347]

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

Ok, I see. But why is it giving me a steady voltage on the main caps (163V), and when I remove C4, I get a steady voltage of approx 18V on pin 3. Whenever I reinstall C4, everything starts to jump around?? R10 (1.5Mohm) is what cuts the 163V down to 18V, and it is steady when C4 is out and bounces when C4 is installed....

i think that means c4 is trying to start it up but there is a fault stopping it . without c4 it doesn't even bother trying to start .

[harp]

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

I will love to know answer also...
Lost in space... try measure voltage (with decimal point max resolution) between point A and B, A and C, A and D, A and E, A and F, and A and IC Pin#1 (gnd) in DC and AC (mV) settings... in DC settings it has to be about 163V, but I am interesting if after decimal point has any changed along the track... maybe some information arrive... hunting dark shaddow...

[rddube]

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

Ok, I see. But why is it giving me a steady voltage on the main caps (163V), and when I remove C4, I get a steady voltage of approx 18V on pin 3. Whenever I reinstall C4, everything starts to jump around?? R10 (1.5Mohm) is what cuts the 163V down to 18V, and it is steady when C4 is out and bounces when C4 is installed....

[CapLeaker]

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

This is "normal" behaveour when testing a pin who no do any actual switching. Thats readings are false. I think it is some part of bouncing inside measurement circutry or simptoms of insuficient signal form. Frequency must be steady, readable all the time while is probe connected, and always is the same value, repetable itself.

I agree with harp. That resistor won't do Jack, because the PWM is in UVLO for some weird reason.

[harp]

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

With the 56K resistor (I reinstalled the 56K resistor to try it a 2nd time), the frenquency is 51.93HZ and what is weird after about 1 second, it drops to 0 on pin 8. I recheck the frequency, this time it is at 31.03HZ and after a second or 2, drops to 0. On the 3rd try, 51.93HZ and drops to 0. I tried it a 4th time, this time 75.11HZ and dropped to 0 after a few seconds. Weird no?

This is "normal" behaveour when testing a pin who no do any actual switching. Thats readings are false. I think it is some part of bouncing inside measurement circutry or simptoms of insuficient signal form. Frequency must be steady, readable all the time while is probe connected, and always is the same value, repetable itself.

[lotas]

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

You need to install such a socket and experiment.

[rddube]

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

If you haven't changed it to a new D2 yet, try replacing it.

D2, I'm on my 3rd one...do you think it could be the chip itself? The one in there is a 3rd one, but I got 5 of them when I ordered them. The thing is is that the pads that hold the chip are getting weaker and weaker (I have to bridge a lot with solder to make a good connection).

[rddube]

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

So, let stay 100k in there, all datasheet is reffer to 100k.

It is ok that you stay in your comfort zone, especially if you have not used bulb limiter.
FYI there s thing caled luster clamp, luesterklemme, and can screw to fix wire and probes in it, and it is handy to have one in this like situation of 120v flying arround...

Just know we will soon runout of options...
Your psu is fully functional and not working...

What about post #156, you not reply, have you worry anything about that?

Hi Harp, post #156 you said : "Wait aproval if this idea will provide power to ic to test.", so I didn't try that because no one replied. But I did do the inductance testing.

[lotas]

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

If you haven't changed it to a new D2 yet, try replacing it.