DELL 1907 FPT power supply

[PlainBill]

Re: DELL 1907 FPT power supply

hope this help. the output MOSFET are P609 OR AOP609 manufactured by Alpha & Omega Semiconductor

Thank you, Sir!!!

PlainBill

[alexanna]

Re: DELL 1907 FPT power supply

Let's see if I can make myself clear. The power supply and inverter are on the same board, but there are often only two conductors connecting them - Inverter power and ground. (This one seems to have four - possibly multiple traces). The bottom two pins on that connector carry the brightness and On/Off control signals from the logic card.

Why won't an inverter work, even for a brief second? In detail, there are many reasons, but some are easy to check. Let's list a few:

1 No power from the power supply (typically 12 volts, could be higher).
2 No 'On' signal from the logic card.
3 Brightness set too low (again, from the logic card).
4 Defective inverter controller
5 Defective drivers
6 defective transformers
7 On/Off signal not getting to the inverter controller
8 Brightness signal not getting to the inverter controller.

You have already found that 2 and 3 are not the case, but those control signals often go through one or more transistors and resistors. Tracing those lines in a picture is a royal pain in the anatomy; it's only slightly easier if you have the board in hand.

The power is a different matter. Most designs provide power to the inverter whenever the power supply is plugged in. There are two ways to identify the actual traces. At this point you can stop reading and see if you can figure them out.

But I've lead you on the path to enlightenment (that really sounds like I'm full of it) long enough.

Clue 1. Power supply traces are much heavier than signal lines. Ground is easy to identify - somewhere or the other it goes to the pads surrounding one or more of the mounting holes.

Clue 2. Large electrolytic caps (typically 220uF - 1000uF) are used to filter the power supply. Where do we see those? Well, we see two clusters of them in the area of the heat sinks. And we see six of them in the inverter.

So here is your homework. Be careful - voltages up to 160 VDC are present on the power supply!!!

1. With the power unplugged, verify that the - pin of the electrolytic caps in the inverter area actually go to ground.

2. Plug in the power and measure the voltage across those caps. If one or more are at 12 - 24 volts, we know the power supply is working, and the inverter is getting power.

3. Trace the two lines from the logic card as they go to the inverter controller. Make sure they change state as you hit the power button. IF for example the line that goes from 0 to 3.3 volts goes to a transistor, but neither of the other two leads of the transistor change voltage when the button is pushed, you probably have found the problem.

PlainBill

Well here goes .
I am able to answer some of the questions asked. I am reading 24vdc around the caps. In the inverter area. As far as the toggling 3.2v,I can trace it to resistor R118 thru the resistor it drops to .6v to the upper right terminal of q101. At this point I will need some more direction. I hope the new pictures will be of help.
Al.

[PlainBill]

Re: DELL 1907 FPT power supply

Well here goes .
I am able to answer some of the questions asked. I am reading 24vdc around the caps. In the inverter area. As far as the toggling 3.2v,I can trace it to resistor R118 thru the resistor it drops to .6v to the upper right terminal of q101. At this point I will need some more direction. I hope the new pictures will be of help.
Al.

Good work. Now we know there is power for the inverter.

The next question is what happens to the signal from Q101. Check the other two terminals of Q101. One (probably the bottom left) should be at a constant voltage (probably 0 volts), the other should change when the base is toggled. If it doesn't, what are the numbers on Q101?

The new picture was a vast improvement. Continue to trace the signal. If you run into an impasse, a picture covering the area outlined in yellow would help me.

PlainBill

[alexanna]

Re: DELL 1907 FPT power supply

Here we go.
If i concider the single pin as the top. With green light on the bottom left pin reads aprox. .6vdc. with monitor off no green light 0v. there is always ov on bottom right. On the top single pin 0vdc when the is monitor on green lamp on, And when monitor off it is reading .6vdc.
I am running out of gas this evening. I will get better pitcures tommrow .thank you.
Al.

[alexanna]

Re: DELL 1907 FPT power supply

One more question, I have a very good back ground in automotive technology. Can the inverter circuit in any way be compared to an automotive ignition system? Flowing current thru the coil primary and then interrupting it [dwell or H.Z.] to induce high voltage in the secondary? And if so is the inverter controller making and braking the circuit, turning on and off the inverter drivers ?

[PlainBill]

Re: DELL 1907 FPT power supply

Here we go.
If i concider the single pin as the top. With green light on the bottom left pin reads aprox. .6vdc. with monitor off no green light 0v. there is always ov on bottom right. On the top single pin 0vdc when the is monitor on green lamp on, And when monitor off it is reading .6vdc.
I am running out of gas this evening. I will get better pitcures tommrow .thank you.
Al.

Well, that appears to be driving Q102, which might or might not be hooked to pin 4 of I101 - the inverter controller.

You're doing good. Get some rest, tell your SO how smart you are. In the morning, instead of pictures, how about the voltages on all pins of the inverter controller, noting which (if any) change with the power button.

PlainBill

[PlainBill]

Re: DELL 1907 FPT power supply

One more question, I have a very good back ground in automotive technology. Can the inverter circuit in any way be compared to an automotive ignition system? Flowing current thru the coil primary and then interrupting it [dwell or H.Z.] to induce high voltage in the secondary? And if so is the inverter controller making and braking the circuit, turning on and off the inverter drivers ?

A vastly simplified description, but reduced to it's essentials, that's what is happening. I've attached a simplified schematic of an inverter. This uses an inverter controller from the same manufacturer as yours, and drivers that are functionally identical to the ones in yours.

PlainBill

[alexanna]

Re: DELL 1907 FPT power supply

Well, that appears to be driving Q102, which might or might not be hooked to pin 4 of I101 - the inverter controller.

You're doing good. Get some rest, tell your SO how smart you are. In the morning, instead of pictures, how about the voltages on all pins of the inverter controller, noting which (if any) change with the power button.

PlainBill

On the inverter controller, small dot is pin1
1 is 5v on 5v off
2 is 0v on 0v off
3 is 0v on 0v off
4 is 0v 0n 0v off
5 pin above dot is 0v on 0v off
6 is 2.5v on 3.2v off

7 is 5v on 5v off
8 is 0v 0n 0v off

[PlainBill]

Re: DELL 1907 FPT power supply

On the inverter controller, small dot is pin1
1 is 5v on 5v off
2 is 0v on 0v off
3 is 0v on 0v off
4 is 0v 0n 0v off
5 pin above dot is 0v on 0v off
6 is 2.5v on 3.2v off

7 is 5v on 5v off
8 is 0v 0n 0v off

Darn!!! I am REALLY wishing I could find a datasheet for for the OZ9936. Well, wait a minute.

1. I believe you misnumbered the pins on the IC. They are numbered counter-clockwise from the dot, you seem to be saying you went across the bottom, then across the top. That would only change the reading on pins 6 and 7. I've marked up ANOTHER picture.

2. Continue tracing the On/Off signal. The changing voltage on pin 7 (6) I believe corresponds to the brightness signal. That means the On/Off signal isn't getting to the inverter controller, which is very good news.

PlainBill

[alexanna]

Re: DELL 1907 FPT power supply

Yes the voltages are what you have marked in the photo,I did missnumber them.
Also when I checked voltages to the controller I checked them with the monitor on and off,I did not check them the moment the green light came on. I will continue to trace.
Al.

[alexanna]

Re: DELL 1907 FPT power supply

Well here I go thinking again,Question we have a data sheet for the drivers p609 woud there be any benefit to check voltages there,And if so what would I expect to see.
Thanks Al.

[PlainBill]

Re: DELL 1907 FPT power supply

Well here I go thinking again,Question we have a data sheet for the drivers p609 woud there be any benefit to check voltages there,And if so what would I expect to see.
Thanks Al.

If this was early in the game and you wanted a quick check, that would have been useful. As it is, there doesn't appear to be any activity on the inverter controller.

I suspect you measured properly, otherwise you wouldn't have seen dual voltages on pin 7. However, just to be clear, here is how you should check each pin on the inverter controller: With the monitor plugged it, hit the power button on the front until the green light goes off. Check the voltage on pin 1. Hit the power button, the green light comes on, check the voltage again. Move on to pin 2 and repeat, measuring with Green light off, then on.

PlainBill

[alexanna]

Re: DELL 1907 FPT power supply

Well I not sure what happend last night, But rechecking powering on with dvm hooked up reading voltages as monitor is powerd on,I have a differnet reading on pin one,It goes from 0v off to 5v on,Most likely a human memory error.
I guess that could be the on off siginal?
Al.

[PlainBill]

Re: DELL 1907 FPT power supply

Well I not sure what happend last night, But rechecking powering on with dvm hooked up reading voltages as monitor is powerd on,I have a differnet reading on pin one,It goes from 0v off to 5v on,Most likely a human memory error.
I guess that could be the on off siginal?
Al.

Probably yes. Now see if you can trace it back to the control input.

And it would be useful to check the gate inputs on the drivers to see if they change voltage while the green led is on.

PlainBill

[alexanna]

Re: DELL 1907 FPT power supply

Well,I have an idea where this is going and my shakey hands are hoping not.
anyway, using the correct numbering system pin# 4 of the controller apears to to be going to pin 2 of aop609 or gate#2.
Gate#2 shows 0v on and off, gate#1 shows 23v constantly.
thanks Al.

[PlainBill]

Re: DELL 1907 FPT power supply

Well,I have an idea where this is going and my shakey hands are hoping not.
anyway, using the correct numbering system pin# 4 of the controller apears to to be going to pin 2 of aop609 or gate#2.
Gate#2 shows 0v on and off, gate#1 shows 23v constantly.
thanks Al.

A DMM isn't the ideal tool to troubleshoot this, but it should show some difference when the Inverter controller turns on.

By the way, I've tried a unique approach to getting the datasheet for the OZ9936. I asked the manufacturer. So far they haven't indicated it is unavailable, but don't seem to be in a hurry to send it to me either.

PlainBill

[jsaily]

Re: DELL 1907 FPT power supply

Jsaily,
The cfls are not that bad to repair.The biggest problem I have had is dust getting below the lcd.You will need very small screwdrivers and a good memory as how things go together.As I dissasemble I keep every thing together in the order they come apart.Alter you remove the lcd. and all the difusers you will be left with the frame and a thick peice of plastic.Carefuly remove the plasitc leaving the frame and ccfl housing.Be careful with the silicone insulators thet can rip eaisly I have used wd40 to get them moving.There has been enough wire for me to fish enough wire down the housing to resolder.keep your solder joint as small as possible,If it is to big you will increase the length and you will have troubles with reassmbly.Make sure every thing is insulated with no bare wires.Also I am told the yellow kapton tape is a must for heat . My lcd is dissambled at this time I will answer Plain Bills questions as soon as i can.

My monitor is alive! I transplanted the CCFL lamps from the Acer monitor, and now the Dell monitor works perfectly. One of the original lamps glass was broken, and I could smell ozone when testing it. The Acer lamps fitted almost perfectly, I did'nt even need to solder anything. I just moved the lamps and cable assemblies into the lamp holders. Thanks again for your encouragement!

Now I have a working power supply & inverter board for Acer AL1716 if anyone wants it. Sadly I cracked the LCD a bit while putting it back together The logic board was the problem in the Acer monitor.

[alexanna]

Re: DELL 1907 FPT power supply

A DMM isn't the ideal tool to troubleshoot this, but it should show some difference when the Inverter controller turns on.

By the way, I've tried a unique approach to getting the datasheet for the OZ9936. I asked the manufacturer. So far they haven't indicated it is unavailable, but don't seem to be in a hurry to send it to me either.

PlainBill

Well I am not quite yet ready to give up on this just yet .I have been following welshs 101 thread about coils.
I fee l it is better I ask my question here. Very simply if I am understanding this correctly, In order to get some back light activity there is going to have to be current flow thru the primary winding of the coil that is interrupted very rapidly over and over. I think at this point I know that I have a on off signal and brightness signal going to the B.L. controller, But I do not know if it is asking for back lamps. There is a very good possibility I can get use of a scope .Reading between the lines I think maybe that was what you were referring to?
My understanding of transistors is very basic. But very simply my understanding is that it is an on off switch and it can provide either power and or a ground to turn something on or off. In an earlier post you were asking me to check voltages as I powerd the monitor on and note voltage the gates of ap0609, If the controller was commanding back lamps on is that where I would expect to see some type of high to low voltage happing rapidly.
Thankyou Al.

[jsaily]

Re: DELL 1907 FPT power supply

Well I am not quite yet ready to give up on this just yet .I have been following welshs 101 thread about coils.
I fee l it is better I ask my question here. Very simply if I am understanding this correctly, In order to get some back light activity there is going to have to be current flow thru the primary winding of the coil that is interrupted very rapidly over and over. I think at this point I know that I have a on off signal and brightness signal going to the B.L. controller, But I do not know if it is asking for back lamps. There is a very good possibility I can get use of a scope .Reading between the lines I think maybe that was what you were referring to?
My understanding of transistors is very basic. But very simply my understanding is that it is an on off switch and it can provide either power and or a ground to turn something on or off. In an earlier post you were asking me to check voltages as I powerd the monitor on and note voltage the gates of ap0609, If the controller was commanding back lamps on is that where I would expect to see some type of high to low voltage happing rapidly.
Thankyou Al.

Hi Alexanna, if you don't have access to a scope you can try using a multimeter with Hz measurement capability! Expect the inverter frequency to be between 20-70 kHz. You can touch the circuits on the primary side but may fry your multimeter on the secondary (HV) side. Or you can use the probes as an antenna like in this example:

http://www.fonerbooks.com/test.htm

I have to try this with my Fluke 117 at home too

[alexanna]

Re: DELL 1907 FPT power supply

Ok a up date here,With the top inverter driver removed from circut,I think I removed it several days ago to see if I could test it, I was seeing if I could see a h.z. reading on the driver still in circut Well still no reading noticed.
For some reasion I plugged in the bottom lamps and they light up.But Iam hearing the jittery noise around the bottom transformer and lamps are flickering but they light! Question here I kind of wondering if the coil may be bad?Oh one more thing I reflowed solder joints with solder much earlier but I did not compleatly remove clean and resolder.
Al.