Benq PB6100 won't turn on...any ideas? - Page 4 - AVS Forum
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post #91 of 116 Old 11-05-2010, 05:03 AM
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Ok reading this thread was like a mystery novel and it seems the last page is now missing. Did anyone get their projector to work again???? Anyone out there??
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post #92 of 116 Old 12-18-2010, 06:46 PM
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Had the same problem as most of you guys..replaced L714 and measured the SMD caps around the DAD1000 chip. Noticed that C701 and C735 had shorted. So a quick replacement with some spares, powered up and blue screen with BENQ logo...Give it a try before scrapping your PB6100's as if a white screen i present it does mean that most of the peripherals are operational just that there is not signal to he DMD chip from the DAD1000 chip. and if you are lucky enough just by replacing those caps (Measure them first) and if your DAD1000 chip is not fried, you will be back in business. the two caps are connected to the VBIAS and VRST rails...give it a try and repost your results. Cheers!
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post #93 of 116 Old 12-20-2010, 02:02 PM
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Anyone still looking for a cure or still have their projector? Mine failed with the same symptoms and I just purchased the service manual. I plan to study it over the next few days.
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post #94 of 116 Old 12-26-2010, 12:30 AM
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rmgruendel

have you tried measuring the caps i mentioned in my previous post?
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post #95 of 116 Old 12-27-2010, 11:23 AM
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Yup. I was fully prepared to fix this baby. I was very naive going into this. I ended up downloading the TI manuals for their chips. I warmed up the soldering iron, multimeter, cap meter and O-scope. Then I opened the main board and found the DAD1000 chip split in half. I read the TI manual where they are very clear the DAD1000 chip must have highly regulated voltage of damage will occur. In summary, the main board is unrepairable. I spoke to BenQ about repairs just to put my mind at ease that I had explored all options. The customer service rep was very honest and steered me away from service. He said "I cannot tell you that what you have read online is accurate, but I will tell you that I would not try to repair this model of projector." I thanked him for his honesty and hung up. It did annoy me when he said that the projector was very old. Seriously? Six years is considered very old?
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post #96 of 116 Old 12-27-2010, 11:25 AM
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I started a brief search on projectors that met my budget and required features, then I let out a curse when a GD BenQ came up as the first result.
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post #97 of 116 Old 12-27-2010, 11:31 AM
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I think one of the lessons learned here is in this case I got what I paid for. At the time this was the least expensive projector with these features. Don't get me wrong it hurts to have to throw away anything that cost $1,700 and was not over ten years old (3500 hours of use), but it doesn't change the fact that the closest model with the same performance was 50% more. Which leads me to a question for all the suffering PB6xxx owners.

Where do you go to learn what a manufacturers quality and service history is?
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post #98 of 116 Old 12-30-2010, 04:34 AM
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Ouch the DAD1000 chip split in half? talk about a poor design on the power regulation side. well i found that many component dealers in china do have stock of the TI DAD1000 chip but than again like you said i think its not worth it. So far i have fixed 4 units with the same problem and i have noticed a simple problem like a loose cable would cause the caps near the DAD chip to give way.

As to answer your question on the history and quality, i guess the only way is look at blogs regarding a particular model you are interested in and do an indepth study on the common problems owners face. Tho problems may not arise immediately but its a start. Another important aspect to consider is the cooling of the projector. Most of the designs i have seen have poor cooling which leads to component failure and most importantly do not ever leave your projector on standby when not in use, as most of the chips on the mainboard are still on without the aid of any cooling. Even tho they are designed to withstand high operating temps but still why waste the lifespan of a chip when not in use.

Just my thoughts,
Cheers
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post #99 of 116 Old 02-06-2011, 08:35 AM
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Well, my PB6100 lasted about a year and a half after changing out the capacitor and yesterday, I heard the terrible "fan" sound again.

I took it apart and the same capacitor had blown - Argh!!!

Luckily I had a spare and replaced it. Powered it up and it worked like a charm...until about 15 minutes of use...then it seemed like the image was phasing in and out of colors/brightness....then the lamp turned off and the Lamp light is blinking red. I power cycled and tried a few other things (re-seating the lamp), but the lamp light still flashes red.

From what I know, there is no way to test the lamp. The lamp only has around 1000 hours on it, so it 'should' still have lots of use on it.

Any ideas out there on how to troubleshoot it. I would spend the money on a new lamp (I've found them for around $150 online) if that was the issue (and hopefully get another few years out of it), but definitely don't want to waste the money if it isn't the problem.

Any suggestions?

Thanks.
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post #100 of 116 Old 05-07-2011, 12:34 AM
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Hi all,

I too have the Benq PB6100 and have had same cap 25V 470uF blown.

I have managed to replace the cap but the rear fans do not turn on.

The projector turns on and I get the blue screen with the BenQ logo and after about 10 seconds the bulb turns off and the Power and Temp light flashes red while the lamp light flashes green.

I have looked over the board the fans are connected to and can not see anything else damaged.

I am not sure how to test each component but I do have a multi meter to use if somebody can guide me. Can anybody give me and idea on what to check?

Thanks
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post #101 of 116 Old 05-07-2011, 03:56 AM
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I also have a similar problem with my PB6200. I wonder, how many people were able to change the capacitor and have a working unit? is it worth the effort?

Thanks!
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post #102 of 116 Old 05-08-2011, 01:10 PM
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I changed the capacitor... now it does power on, but it would be a white screen!
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post #103 of 116 Old 07-16-2011, 12:59 PM
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My PB6100 had the same symptoms and I found this forum.
I looked for the 470uF cap and it was dead. Replaced it, fixed a cable I broke in the meantime, turned it on .... tam tam and IT WORKED again.

Thanks to this forum and SyncMaster750b.
There should be a counter for dead PB6100/PB6200 and perhaps even more BenQ's with the same Power-supply board, which could be revived and which could not be revived.

Think 20% they could be revived rest is dead.
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post #104 of 116 Old 07-16-2011, 06:39 PM
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Same thing for my PB6100. Bought it used about 2.5 years ago (it came with my house). A couple weeks ago I heard the fan noise. Figured the kids left it on so I went to turn the power off and it would not turn off. I then unplugged it.

Went to turn it on a few days later and same thing. Automatically figured it was the bulb so bought a new one and replaced it...wasted $130.

After finding this forum I took a look at the cap, same exact one blown.

Oh, well - cheap crap, what can you expect. Never heard of benq before this, now I know not to ever buy that brand again.
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post #105 of 116 Old 12-13-2011, 09:13 PM
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Followed the advice and checked the capacitor as in the picuture and sure enough it was blown. I'll be replacing and let y'all know how it worked out.
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post #106 of 116 Old 02-05-2012, 01:35 PM
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I have the same issue on my unit, replaced the cap, and now it powers on OK, but now the white screen issue. Does anyone have a fix for this?
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post #107 of 116 Old 02-05-2012, 01:57 PM - Thread Starter
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My issue was that I believe the blown cap also caused the main board to fail, and it just wasn't worth it at the time to replace the main board and cross my fingers. I sold it for parts for $75.

If nothing from this post works for you, then cut your losses.
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post #108 of 116 Old 06-29-2012, 01:15 PM
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Great post...

same problem from Spain: my benq pb6100 wasn't been used about 4 years ago, but now we'd like to see spanish team to win eurocup football this sunday...
i tried to switch it on again... bur no result. leds binking, but no further start.¿¿??

Thanks to all of you, reading the posts... 470micros cup was blowned out. I repaired it.

but i got the same behavour. I took a look to main board. Looked like C824cup was allright, but there was a low resistance on this line: about 12ohm for this 12V line.

looking everywhere... and f****g DAD1000 chip is fried out.
I just bought last week a brand new lamp, now of no use. 200€ went away...

Anyone needs spare parts?
Anyone sells a mainboard with working DLP DAD1000?

So, i asked to service support in Madrid, and same result as some of you:;
- no tech info available at all
- send pj, and pay 50€ to be checked.
- then receive quotation:
- if you accept that, then pay again
if you dont accept that, then renounce to pj, so that they get it (¡¡¡but they dont pay you anything!!!)

I'm angry with that people, and they cannot even speak spanish properly.

This is how the internet will change the world: contacting people around the world, so that we can be in touch with each other.

And complaining if we are not happy.

My wife told me that in worten there is a pj about 250€... the cost of the lamp.
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post #109 of 116 Old 10-19-2013, 10:42 AM
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A little late to the party but I got my PB6200 working again thanks to you guys. smile.gif
The power supply cap was blown and the DAD IC was burnt. I'm an electronic tech and work on parts like these all day so swapping the parts isn't too hard for me I just had to find them. The cap was fairly easy to source but I had to order the DAD IC from China. Frickin shipping was more than the parts but I got over that when the projector powered up. smile.gif

I have a few more DAD ICs left over if anyone is interested in shipping their projector to me for repair. I can't guarantee 100% that it will work but those two components did it for me. I'll look over your whole video processing board and make sure there isn't any other damage. Not looking to take advantage of anyone or get rich so how about it you just send me your video board (the one with the DAD) I can replace it for $50 plus return shipping. If you send the whole projector $80 plus return shipping.
Or I guess if you've long since given up on the projector and already replaced it I might be interested in buying it to see if I can get it working. I have a friend that is interested in using a projector for his game room.

Great forum smile.gif
-Jesse
maherj21@yahoo.com <--- I'll try to keep checking back on this thread but in case I forget this is the fastest way to get ahold of me.
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post #110 of 116 Old 11-10-2013, 09:12 AM
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Just chiming in on the story.. About 2 years ago my PB6100 wouldn't turn on. Ye olde 470uF/25V cap had blown. Replace.

 

Then again the other day, I find 1 pj fan constantly running and try to turn the pj on but no joy. Replace 470uF/25V cap AGAIN, but now I get the familiar grey picture.

 

Crack open the motherboard and...

 

 

 

C701 measures 5 ohms, C735 measures 37 ohms. (Same measures with reversed polarity.) Can't be healthy.

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post #111 of 116 Old 11-10-2013, 10:08 AM
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Quote:
Originally Posted by mikeclueby4 View Post
 

Just chiming in on the story.. About 2 years ago my PB6100 wouldn't turn on. Ye olde 470uF/25V cap had blown. Replace.

 

Then again the other day, I find 1 pj fan constantly running and try to turn the pj on but no joy. Replace 470uF/25V cap AGAIN, but now I get the familiar grey picture.

 

Crack open the motherboard and...

 

 

 

C701 measures 5 ohms, C735 measures 37 ohms. (Same measures with reversed polarity.) Can't be healthy.


I have replacement DAD1000 ICs if you want to send the video board to me for repair. (see post above yours)  I'm an electronic tech and work on these size of ICs (and smaller) every day.

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post #112 of 116 Old 11-10-2013, 11:28 AM
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Quote:
Originally Posted by maherj View Post
 


I have replacement DAD1000 ICs if you want to send the video board to me for repair. (see post above yours)  I'm an electronic tech and work on these size of ICs (and smaller) every day.

 

Awesome offer there mate but unfortunately wrong continent - unsure if it's worth the hassle over just getting something in the $500 class. (I guess I'm waiting another year for a snow machine. Damn.)

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post #113 of 116 Old 11-12-2013, 02:07 PM
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I've made my arrangements to ship my video board off to maherj. I'll update afterwards with my status.

For what its worth, my suspicion about the failure scenario everyone has been seeing goes something like this:
  • Cap C7302 is getting damaged somehow (maybe bad shutdown transients)
  • The cap failure drags Vdd down.
  • Unfortunately, Vdd provides the reference control for the off-line switcher, so the switcher raises the input to the transformer in an attempt to raise Vdd to 5v.
  • This input voltage rise brings up the voltages on the transformer taps not tied to Vdd, notably the 12v one (in my case 28v on that tap).
  • The system won't power up the 5v with Vdd so low, but the internal fan fails on with the low Vdd and high 12v
  • 20v cap C828 may blow depending on the amount of overvoltage and length of time the overvoltage is present before you notice it
  • The DAD1000 12v input is simultaneously unprotected and sensitive to over voltages, so it winds up burning out in all but the luckiest scenarios

Of course there are about half a dozen other things that may blow because of the overvoltage, but the DAD and C828 appear to be the most sensitive.

I am pretty surprised that they didn't throw any sort of overvoltage protection on the fan board for the 12v line. It seems like a pretty big oversight. Based on the number of people who have replaced C7302 only to have it blow a second time, I may consider adding some to mine.
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post #114 of 116 Old 11-12-2013, 02:17 PM
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I was saying to myself.. "Damn, I should have put 2 new caps in, in parallel."  because I seriously was considering doing it on the first replace.  Also not mounting it upside down with its head against a vibrating fan.

 

Edit: perhaps using a few ohms worth of resistance wire instead of regular wire.

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post #115 of 116 Old 11-21-2013, 08:57 PM
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I got my video board back after sending it to Jesse (maherj) for DAD1000 replacement (see post 109 for his contact info).
And success. After 3 years my paperweight is again fully functional. smile.gif

Highest compliments to him, he did great job on the replacement, communicated every step of the way and fixed and returned the board very quickly.
For anyone interested, shipping the video board in a small USPS flat rate box was 5.80 each way with 2-day delivery, and tracking (obviously shipping the whole projector would be more).

Here is a picture of the installed replacement DAD (original DAD is taped to the lower corner of the video board).


While I was waiting to receive my board back, I looked into other parts that may have been damaged and worked on finding a potential fix to prevent future damage to the DAD.

Here is what I came up with:


Possible damaged components from the 470u cap, C7302, frying and leading to 12v and 18v rail overvoltage (video board unless otherwise noted):
  1. DAD1000; has very tight voltage tolerances, and they aren't kidding. By the time you can notice symptoms from the fried cap, your DAD1000 is quite likely fried.
  2. Surface mount electrolytic capacitor c828. Rated for 20v, it seems a few people have had this fail. If it fails before the DAD, you are one of the luck few.
  3. Surface mount inductor L714, L703, the only way I could see these failing is during total meltdown of the DAD
  4. Other stuff attached to the DAD. Depending on how the DAD melts, it could destroy a few connected parts, but the likelyhood is low
  5. DLP chip. This falls into the category of stuff attached to the DAD, but figured it merited its own entry. If the DAD went thermonuclear, it could damage or destroy the DLP. No evidence that this has happened to anybody in the field.
  6. A8904SLB Colorwheel motor controller. I saw double the 14 volt rating at Vbb, but the chip is switched off during the overvoltage, so damage is unlikely.
  7. FA5502N on the Power board (was expecting 18v, received close to 40v). A very robust chip that is designed for 30v, It looks like it generally exceeds its design spec by fair margin and should be relatively safe.

Possible mitigation solutions for 470u cap failure issue:
  • Replace C7302 with a 470uF, 35v, 105deg C part
  • Add flyback diode, probably across the pins of the electrolytic cap C7302 (the one that always blows). This should prevent reverse bias situations that can damage the cap over time.
  • Add a 12vdc regulator on the wire between the fan board and the video board. This will be a little tricky as the 12v powers the DAD and the colorwheel controller, so it draws quite bit of power (probably about 1.4 amps. I still need to test to find out for sure). This will cause some heat dissipation issues and means we can't use the standard 1 Amp LM7812's. Fortunately, just about all the regulators have built in overtemp protection, so they should fail in a way that saves the DAD even if they wind up dissipating more heat than expected. As a bonus annoyance, there isn't much free space inside the case.

So, to summarize:
  1. If your projector won't turn on and you hear the internal fan running with the projector off.
  2. Cap C7302 on the Fan board is almost certainly blown
  3. If, after replacing the Cap, you only see a mottled white screen, your DAD1000 is fried. Replace the Cap and send the DAD out to be replaced.
  4. If Cap C828 is blown, your DAD1000 may be ok, but probably isn't Not sure what symptom you see for this one.
  5. If anything else on the Video board is blown, your DAD probably had a catastrophic meltdown
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post #116 of 116 Old 02-13-2014, 06:47 PM
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Hi! I'm selling my Benq PB6100 motherboard, this is damaged. Anyone is interested? I ship worldwide!

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