Acer PD726W DLP Projector - No Power

[bw1]

No sign of power - normally a single LED lights when connected to power.

*Main AC input fuse OK.
*Power supply visually OK - picture attached.
*Main board has three bigger surface mount electrolytics that I'm questioning - pics attached for comments.

I know these things have too many brains as far as not powering up if bulb is bad, etc. but bulb looks good.

Any ideas?

[Rob Northen]

Re: Acer PD726W DLP Projector - No Power

I guess a good start would be to measure the voltage over the big filter mains cap

[bw1]

Re: Acer PD726W DLP Projector - No Power

Only 3.7vAC...? Definitely something wrong. There is an interrupt switch I saw in the service manual that I'm going to check first - with the power supply out, that's unhooked. I'm not sure what exactly it "interrupts," but it very well could be main power.

I'll let you know what I find out.

[bw1]

Re: Acer PD726W DLP Projector - No Power

Well, with the switch pushed, I get 65v between either side of cap and ground. With the switch in its normal position, the it looks like it went from 3.7 up to roughly 9v at the main big cap.

Pictures of interrupt switch attached.

[retiredcaps]

Re: Acer PD726W DLP Projector - No Power

Across the main filter capacitor, you want to measure DC V across the legs.

[bw1]

Re: Acer PD726W DLP Projector - No Power

Well what the hell. I even know that. I'm obviously new to component-level troubleshooting, but I'm not sure what I was thinking there. I think my sleep-deprived mind got confused because I was testing the fuse, and "mains cap" seems like it would be, aww hell, nevermind. Anyway...

Yes, voltage is the expected 170v when interrupt is pressed in.

[retiredcaps]

Re: Acer PD726W DLP Projector - No Power

Yes, voltage is the expected 170v when interrupt is pressed in.

Okay, 170V DC is good.

There is a connector with 7 caps next to it (UCC KY, Green cap, and maybe 3 Capxon caps).

Are there any voltages on the pins of that connector?

If yes, what are they?

If no, is there any DC voltage across those 7 caps?

[lti]

Re: Acer PD726W DLP Projector - No Power

The three big surface mounted caps are bulging.

[retiredcaps]

Re: Acer PD726W DLP Projector - No Power

The three big surface mounted caps are bulging.

When I first saw those pictures, I had the same thought, but I think those caps are supposed to look like that?

[bw1]

Re: Acer PD726W DLP Projector - No Power

Yeah I'm on the fence too - they're odd little buggers. They don't immediately look bad, but they're not flat either. Here's a picture I found from an ebay listing, and they definitely look flat here, but I'm still not sure. I suppose without an ESR meter, I can't really tell for sure, eh?

[lti]

Re: Acer PD726W DLP Projector - No Power

I haven't seen a cap that was intentionally manufactured with a domed top. You could test them to make sure. The cap will have high ESR and low capacitance if it really is bad.

[bw1]

Re: Acer PD726W DLP Projector - No Power

Retiredcaps - yes there are common voltages on the small connector - 12, 5, 3.3, etc. I'm guessing power supply is fine, for now anyway. I don't have a pinout of what is supposed to be there, but it looked normal enough.

Sounds like these caps are a good place to start? I'm guessing they could cause it to act (externally) as if there was no power to the main plug?

I've replaced lots of through-hole capacitors, but no surface mount. Not sure on the difficulty or procedure here.... anyone have any pointers or suggestions?

[carsonc]

Re: Acer PD726W DLP Projector - No Power

I am having a similar problem with my Acer XD1150. When plugged in, the system powers up briefly (1 sec) and then the power LED, temp LED, and lamp LED flash simultaneously, and then the system shuts down. The fan continues to turn slowly and sporadically.

I have disassembled it as per the service manual instructions, but have little idea as to what to do next. The capacitors on the power supply look similar to the ones you show, with the scored cap bulging out slightly. I have no esr meter handy. What was the prognosis on your projector? Thanks.

[bw1]

Re: Acer PD726W DLP Projector - No Power

Still sitting here. Haven't had time to do anything with it. I was actually thinking about coming back here and asking for more opinions on whether or not the capacitors in my pictures look bad or not -- I couldn't decide for sure. They're not "normal" capacitors. I also do not have an ESR meter handy.

One difference between yours and mine is that mine is completely dead; yours does show sign of power, albeit only for a moment.

[badskum]

Re: Acer PD726W DLP Projector - No Power

Anyone was able to fix the no power problem on this projector?