Benq G2255 doesn't power on - amber power light when plugged in

[budm]

Re: Benq G2255 doesn't power on - amber power light when plugged in

I look real close at the pictures of the IC, the P/N as printed on the body is MP10091ES which I believe it is not the same as MP1009.

[rddube]

Re: Benq G2255 doesn't power on - amber power light when plugged in

[/I][/B]
Yep, I wonder if there is trace on pin 4 that goes under the IC.

I tried to find a trace from pin 4, but it doesn't seem connected to anything, not even pin 7 which gives me 47 kohms resistance. Here is a picture with a light under the board.

So the voltage at C801 is ~20V and at pin9 is 15,5V. What resistance is R804?
Check Q808 in diode mode for shorts.

Dumah, not sure what you mean by this. I have a diode mode, but I check from wich pin to which pin and how do I see if there is a short? I tried reading from pin 4 to pin 5 (red on pin 4), pin 4 to pin 6, pin 4 to pin 7, pin 4 to pin 8 and and I get 1.5V reading in diode mode on all those pins. If I reverse my probes, I get from pin 4 to 5 and 4 to 6 - 0V, and from pin 4 to 7 and 4 to 8 - .75V???

[budm]

Re: Benq G2255 doesn't power on - amber power light when plugged in

Has anyone ever purchased an S.M. from this site?

http://www.service-manual.net/ashop/...?product=56211

You might spend the $13, and get something generic, or similar to
what you've found for free.


Edit: Also, with power off, please check resistance between pin 4 and pin 7. There may be a trace under the chip. Thanks

Yep, I wonder if there is trace on pin 4 that goes under the IC.

[Dumah Brazorf]

Re: Benq G2255 doesn't power on - amber power light when plugged in

So the voltage at C801 is ~20V and at pin9 is 15,5V. What resistance is R804?
Check Q808 in diode mode for shorts.

[will62]

Re: Benq G2255 doesn't power on - amber power light when plugged in

Has anyone ever purchased an S.M. from this site?

http://www.service-manual.net/ashop/...?product=56211

You might spend the $13, and get something generic, or similar to
what you've found for free.


Edit: Also, with power off, please check resistance between pin 4 and pin 7. There may be a trace under the chip. Thanks

[budm]

Re: Benq G2255 doesn't power on - amber power light when plugged in

It is single layer board so that is just a pad for test point.
I sure like to get the correct diagram, I am sure we can bypass the protection circuit but I do not really want to do that but we may have to to do the test.

[will62]

Re: Benq G2255 doesn't power on - amber power light when plugged in

I'm going to throw in a few notes:

1. You measured 5.5v on pin 1 (OV2). From the datasheet: "If the voltage at OV2 is always above 4.9V, the controller will treat this as a short circuit condition after a certain delay. The Fault Timer will
start ramping up."

2. In order to use external PWM dimming (pin 8), pin 7 must be pulled high
first. Is it possible that JW8 is covering 2 bases? Pulling pin 7 high, as well as activating pin 4 (enable).

3. It is possible that the solder point next to pin 4 is over a via to a sublayer
track that you can't follow. With power off, you could use your meter (resistance) to find where the track resurfaces.

4. A little odd that you measured 0v on pin 5. Over 1.2v is supposed to indicate that a fault has tripped the protection circuit. Shorting pin 5 to ground, bypasses the chip's protection circuit. (I would get Budm's advice before trying that.)

[budm]

Re: Benq G2255 doesn't power on - amber power light when plugged in

So at this point pin 4 (EN) does not look like it is being use to turn inveter circuit on/off like as shown in the circuit.
The two control signal lines seem to be going to pin 7 and pin 8.
May be you have to trace out and see if pin 4 is connected to anything else beside C802.

[rddube]

Re: Benq G2255 doesn't power on - amber power light when plugged in

Hello Budm,

I'm sorry, I am still learning at this stage and your drawing makes it pretty clear what is ground and what is not. I was measuring the right pins, on the pins themselves.

I have attached annotated photos for the opposite side of the resistors to 5V and the voltages I get on the pins. I also measured the voltage on that point in Will62's photo for reference.

Please bear with me, I promise to listen and try and understand the first time

Many thanks for your help and guidance.

[budm]

Re: Benq G2255 doesn't power on - amber power light when plugged in

Did you look at my pictures on post 39 that I clearly marked where GNDs are?
Again, look at the left side of R802, it is connected to GND.
C805 is also connected in parallel with R802, the right side of R802/C805 are connected to pin 7 of the IC, so I do not see how you can say that one end of R802 is connected to pin 4!
Your picture here https://www.badcaps.net/forum/attach...6&d=1515675227
Clearly show the reading of 0.09V at TWO PLACES, both if them are GNDs. I do not see any arrow pointing to pin 4 at all.
See my new pix that I have marked again.
It looks like I am getting wrong DATA from you.
Are you sure you count the IC pins correctly or may be we are not looking at the same pictures same board?

[rddube]

Re: Benq G2255 doesn't power on - amber power light when plugged in

Good evening gentlement.....didn't have time to do the tests tonight, but I did take a closer picture of the chip and surroundings. The other side of R802 seems to be connected with the cap that goes to pin 4?

The voltage I get on pin 4 is .092V, so if that is ground where does pin 4 get it's voltage from?

Anyhow, I will do the tests that you asked Budm (and will do the test that Will62 suggested) and report on my findings very shortly. Thank you for your patience.

[budm]

Re: Benq G2255 doesn't power on - amber power light when plugged in

https://www.badcaps.net/forum/attach...9&d=1515615274
https://www.badcaps.net/forum/attach...6&d=1515675227

" At resistor R802 is where the voltage drops. R802 is a 304 resistor, so 300K, I was getting a reading in the megahoms. So I changed that resistor thinking it was open with a good 304 smd resistor. I now get 30K reading in ohms and when I apply voltage, I still get .09V on the left side of the resistor???"
BTW, that point in the picture that you show .09V on the left side of R802 and the other test point you show is CIRCUIT GND!
What do you actually get at pin 4?
BTW, the picture is not super clear for me to trace the circuits in real details so I am not sure if the traces for pin 7 (BOSC) and pin 8 (DBRIGHT) I marked are correct or not.
Need to verify if the right side of R802 (left side of R802 is connected to GND) is connected to pin 7 of the IC or not.
The circuit looks to be about the same as shown in the spec sheet of the IC.
I can see EN pin 4 connected to cap C802 (another end of the cap is connected to GND) but I cannot see where else pin 4 goes to in the picture.
Also you show one of the control line has 3.9V, what is the Voltage of the other control line?

[budm]

Re: Benq G2255 doesn't power on - amber power light when plugged in

Here you go for the resistors. It might look as if the wires are touching each other in the photo, but don't worry they are not when I am under test.

I then traced the circuit that goes from the connector and feeds that pin 4, photo attached with voltage readings along the circuit. At resistor R802 is where the voltage drops. R802 is a 304 resistor, so 300K, I was getting a reading in the megahoms. So I changed that resistor thinking it was open with a good 304 smd resistor. I now get 30K reading in ohms and when I apply voltage, I still get .09V on the left side of the resistor???

So then I thought C805 might be the problem so I unsoldered it and tested it out of circuit 239pf, ESR 2.9, and without it soldered I still get 30K reading on the resistor, so I just resoldered back the capacitor. Tested the voltages again a second time to make sure, and I get what is in the picture???

So what Voltage do you get on each end of the those 3 resistors (not the end that connected to the 5V)?

[budm]

Re: Benq G2255 doesn't power on - amber power light when plugged in

For the lamp detector error to work, the lamps has to fire up first hen the error detection will kick in if the the lamps fail (only takes one bad lamp for the shutdown to happen) to conduct (or open circuit, I.E. no lamp connect) after firing Voltage is applied to the lamp, but since the lamps never did flash (I doubt that both lamps are bad) on for seconds. The circuit also has over current protection.

[will62]

Re: Benq G2255 doesn't power on - amber power light when plugged in

The MP1009 chip internally pulls the enable pin to ground if a current/voltage fault with the lamps is detected. The fault detection delay time for this chip is 220us. That is far too fast for you to capture changes with an RMS meter. Even a good meter with peak/max function requires ~250us to register. If you have a meter with the max function, could you go back to post #30 and try what is detailed in pic#2?

[rddube]

Re: Benq G2255 doesn't power on - amber power light when plugged in

Hello Rddube,
I've been following your progress on this BenQ. I'm adding a couple of pics that may help you until Budm gets back to you. The schematic is for a different model, but uses same/similar driver chip and dual mosfet. Hopefully it will help you follow how this chip handles fault detection.

Hi Will62,

Yes the schematic seems very close to my model, in fact I have another one that I posted earlier that I thought was the right one, but they all have some differences.

Trying to figure out why I get a voltage drop on the resistor mentioned in the post just before that I point to in the photo.

[rddube]

Re: Benq G2255 doesn't power on - amber power light when plugged in

Here you go for the resistors. It might look as if the wires are touching each other in the photo, but don't worry they are not when I am under test.

I then traced the circuit that goes from the connector and feeds that pin 4, photo attached with voltage readings along the circuit. At resistor R802 is where the voltage drops. R802 is a 304 resistor, so 300K, I was getting a reading in the megahoms. So I changed that resistor thinking it was open with a good 304 smd resistor. I now get 30K reading in ohms and when I apply voltage, I still get .09V on the left side of the resistor???

So then I thought C805 might be the problem so I unsoldered it and tested it out of circuit 239pf, ESR 2.9, and without it soldered I still get 30K reading on the resistor, so I just resoldered back the capacitor. Tested the voltages again a second time to make sure, and I get what is in the picture???

[budm]

Re: Benq G2255 doesn't power on - amber power light when plugged in

Thanks Will. Ok Budm, here are the results of my measurements with all 3 resistors connected:

Pin 4 = .092V
Pin 9 = 15.5V
Pin 13 = 5.3V

I also found this schematic which seems to be very close to the one I have, attached.

You are not getting the Enable signal on pin 4, it should be >2VDC.
EN Function
The MP1009 has integrated EN function with
the feedback compensation pin COMP. A logic
low (typical below 0.5V) turns off the IC. An
open collector (OC) si gnal is req uired as EN
signal which connected to COMP.
Can we see pictures of the board showing us how you have the resistors connected?

[rddube]

Re: Benq G2255 doesn't power on - amber power light when plugged in

Thanks Will. Ok Budm, here are the results of my measurements with all 3 resistors connected:

Pin 4 = .092V
Pin 9 = 15.5V
Pin 13 = 5.3V

I also found this schematic which seems to be very close to the one I have, attached.

[budm]

Re: Benq G2255 doesn't power on - amber power light when plugged in

https://www.badcaps.net/forum/attach...8&d=1515615274
Check the DC Voltage on pin 9, 4, and 13.
All the resistors (1K) are still connected in place.