Benq W1070 projector smps

[tibimakai]

I have got this projector(pj) for free, and I'm trying to fix it.
I did not get help in other sections on this forum, so I'm trying my luck here as well.
The pj, has three LEDs(Lamp, Power and Temp) that should indicate, what is the problem with it. In my case, none are on. The only LED, that blinks(very dim), is the power button, which is not included in any troubleshooting info.
I have took the projector apart and I have measured some voltages.
12.65V and 3.3V are there in the secondary output(CN701 connector).
I also have 171V at the main capacitor, after the rectifier.
What I don't have, is the 385V that should supply the ballast for the bulb.
Also, I have measured two more voltages in the primary side, 21V PFC and 19Vcc and these are much lower. 15.4V PFC and 11.2Vcc.
I can't find datasheet, for STR-W6262A, so I'm stuck with the repair.
I'm attaching the PS schematic(elektrotanya, has the full sm) and the datasheet for the FA5502M IC.
I'm guessing that somehow the PS has to be turned on, right? I don't know how, though. Should I use a resistor(what size ?), between 3.3V and pin #14 at the CN701?
Any help, would be appreciated.

Tibor

[CapLeaker]

Re: Benq W1070 projector smps

or there is something wrong with the PFC. If it doesn't work, nothing else works either. You need to see 390V or so on the main filter cap. You measured 171V on it, that tells me either the PSU isn't turned on, or if it is turned on the PFC isn't working.
As for the resistor size I use something around 1k Ohm.
Can we see some pictures both sides of the PSU?

[tibimakai]

Re: Benq W1070 projector smps

Thanks for trying to help.
Today, I have plugged everything back together and I have measured the pins ,at CN701 and both voltages are oscillating. That is why the power button LED blinks.
With Min/Max, the most that I have measured is 4.7V and 1.4V.
Without the main board connected, these voltages are stable. Something is bad on the main board?
I have took some quick phone shots. Most likely they are not good enough for diagnosing the boards. But at least, you have an idea what we are talking about.
Without the main board connected, I have measured the optos, between pin numbers #3 & #4 and I'm measuring 1.00V, at IC652 and 15.3V, at IC653.

[CapLeaker]

Re: Benq W1070 projector smps

Either the main board is drawing too much current from the PSU due to some sort of a fault, or the stby circuit from the PSU can't provide enough current required for the main board to run properly.
Check or replace that cap that runs the STBY circuit on the PSU. You can also use a bench power supply and feed the main boards STBY with it and see what happens.

[tibimakai]

Re: Benq W1070 projector smps

If I would use a 1K resistor, between pin #13 and #14(CN701), the power supply should turn on, right?
STBY capacitor, is C712?

[CapLeaker]

Re: Benq W1070 projector smps

yeah, c712 is on the 3.3v rail. Check or replace it. The PSU should fire up like that as you said above.

[tibimakai]

Re: Benq W1070 projector smps

To tell you the truth, yesterday I have shorted the pins and nothing happened.

[R_J]

Re: Benq W1070 projector smps

The standby power supply needs to be stable before I would wory about the pfc power supply, If the 12volt and 3.3 volt are not stable, check or replace C661 (47/50v) and C662 (47/50v) If they are weak the smps will not be stable.

[CapLeaker]

Re: Benq W1070 projector smps

yeah and it won't until the STBY rail is stable at 3.3V. As RJ already said, wouldn't hurt to check / replace the 12V caps as well. In order to test the 3.3V rail, just load it up with a light bulb or a resistor and see how much current it can supply.

[tibimakai]

Re: Benq W1070 projector smps

I have replaced all three capacitors, but there is no change.
I will still have to try it out, with a bulb. Flashlight bulb and car bulb, right?

[R_J]

Re: Benq W1070 projector smps

The manual gives the current ratings of the supplies, 12v 3amp, 3.3v 30ma. I would load the 3.3 with about a 100 ohm 1/2w resistor, the 12 volts would need about a 5 ohm 30w resistor to draw about 2.5 amp.
So you might need a couple 12 volt lamps on the 12 volt line depending on how much current easc lamp draws, they are not all the same.

[tibimakai]

Re: Benq W1070 projector smps

I will do these tests, as soon as I can. I'm insulating and installing drywall in my garage(man cave) and I can't work fast enough these days.

[tibimakai]

Re: Benq W1070 projector smps

I'm not really sure, how to do these load tests and measurements.
I should add these resistors, and measure the voltage? It shouldn't drop?

[R_J]

Re: Benq W1070 projector smps

That is correct, 100 -75 ohm across cn701 3.3v (11,13) to (7,9) ground should load the 3.3 volt line.
a 12 volt lamp or 2 across cn701 12v (3,5) to (7,9) ground should load the 12 volt line, this line should supply at least 2 amps. without droping
If those voltages stay up, check the voltage across C662 (remember this cap is on the hot side) and is not measured to cold or chassis ground. this voltage supples the vcc for the pfc ic.

[tibimakai]

Re: Benq W1070 projector smps

I have a 6 Ohm/50W resistor. I will plug it in right now. One sec.

[tibimakai]

Re: Benq W1070 projector smps

I have 10.22V.
3.25V on the other.

[R_J]

Re: Benq W1070 projector smps

Thst seem like it should be ok, the 12 is a bit low but I don't think it should cause a problem.
check the voltage across C662 (remember this cap is on the hot side) and is not measured to cold or chassis ground. this voltage supples the vcc for the pfc ic.

What connects to CN702? is it a door switch?

[tibimakai]

Re: Benq W1070 projector smps

Measure, with load resistors removed right?
I have measured these voltages a while back, and they were showing 15.4V(21V PFC) and 11.2V Vcc(19V Vcc).
I haven't measured them, since I have replaced the capacitors, though.

[tibimakai]

Re: Benq W1070 projector smps

C661=11.27V and C662=15.45V.

[R_J]

Re: Benq W1070 projector smps

You can leave loads in place. If those voltages are steady with the loads in place, you must have something on the main board that is really loading down the supply when its connected.
From what I can tell, the 12 volts should not get loaded untill the LP_DRIVE signal it there (page 8),so it could be that the main is loading the 3.3 volt line?