Infocus SP4805 powers on but no lamp

[bluto]

Hello all, its good to be back on bcn! And now my latest problem: My Infocus SP4805 DLP projector from 2006 has been sitting in its box in a cool, dry place for the last year and a half. I pulled it out last weekend but it has decided that it doesn't want to work anymore.

It seems to power on, the fans spin up and the speaker beeps but then after a few seconds the fans slow down partially and it just sits there doing nothing. Eventually the power light blinks out a #1 code which means 'unable to strike the lamp after 5 attempts" The lamp had somewhere approaching 2000 hours (all in low power mode) on it, so it should be good for a while (up to 3000 hrs on low power).

I am pretty disappointed but figure it is probably fixable. I took it apart and did some more troubleshooting. It looked like the color wheel could be stuck since it was only twitching slightly. Apparently it has a speed sensor and will not light the lamp if the color wheel is not spinning at the right speed. I messed with it some more and noticed that after awhile it would twitch more and more and eventually spin up to full speed for a few seconds and then stop. It would do this in a repeatable fashion so I believe that the color wheel is ok and there is probably a power problem.

The power supply has a bunch of lovely suscon caps and a nichicon filter cap. I figure that caps can go bad sitting around so I replace all but one of the caps with Panasonic FC that I have onhand. I powered it back up and it is still doing the same thing. I put the scope on some of the output pins of the PSU and note that there is lots of ripple. So I ordered a new filter cap and one more Panny FC to replace the last suscon.

Those caps cap in today, I installed them but the projector still behaves the same. The ripple is the same as well as seen in the pictures.


TLDR: My projector won't work after 1.5 years in storage. The fans run but the lamp won't come on. I replaced all of the 'lytic caps (including the filter cap) on the power supply board but it still behaves the same. The attached pictures show what appears to be gnarly ripple on the output pins of the PSU. Is there anything else I could check or would I be better off to try replacement power supply for $25 on ebay?

Pics 5&6 show ripple on the 14v leg.
Pics 7&8 show the ac input board outputting ~60v square wave dc

Also attached is the service manual for the X1 which is similar. The voltage specifications are on page 83. The SP4805 seems similar. P/S interrupt was 3.2v, Lamp enable was 1.0v. Lamp lit was 0v.

Power supply/ballast board part number is 510-1894-02

[mmartell]

Re: Infocus SP4805 powers on but no lamp

How can you be certain the lamp is still good ?

[bluto]

Re: Infocus SP4805 powers on but no lamp

Well it worked perfectly before I put it into storage. It should have plenty of hours left on it. Can the lamp go bad just sitting? I tried testing it for continuity.. There was no continuity which I would expect for an arc lamp. Is there any other way to test the lamp?

[mmartell]

Re: Infocus SP4805 powers on but no lamp

Unfortunately you need a known good one to rule it out.

[bluto]

Re: Infocus SP4805 powers on but no lamp

I got a new power supply board from ebay for $25. I installed it today and much to my dismay the symptoms are the same. Still no signs of life from the lamp. Is there a cheap lamp that is readily available that I could use as a test instead of shelling out the $$ for the real thing?

[R_J]

Re: Infocus SP4805 powers on but no lamp

I would check the color wheel, if its not spinning the lamp will not light. It may have stuck from sitting. get access to it an see if it spins freely.

[budwich]

Re: Infocus SP4805 powers on but no lamp

X2... if your color doesn't come up to speed, there will be no lamp lighting. It should come up to speed relatively quickly.... less than 3 seconds. Sounds like the drive of the wheel has an issue.

The speed detector uses the clear section of the color wheel to determine the speed. If it doesn't happen within a time period, it shuts down. Further, the lamp starter will only attempt so many times before it shuts down but that usually happens for a bad lamp. Not sure but, I thought there were flash codes to indicate the failure. Do you see any?

[bluto]

Re: Infocus SP4805 powers on but no lamp

It twitches at first intermittently and then eventually spins up to what looks like full speed for a few seconds and then shuts off. It does so predictably and repeatably which originally led me to think that it was a power problem. But you may be right that the color wheel should spin up quickly followed by the squeal noise from the ballast as the lamp strikes. I have not heard that noise and the fans slowing down after a few seconds could indicate that the projector is giving up on its start up process because of the color wheel sensor not getting the correct reading.

Edit:
I am getting a '1' flash code which according to the manual indicates "unable to strike the lamp after 5 attempts"

[budwich]

Re: Infocus SP4805 powers on but no lamp

I think you have found the issue... the lack of strike success. People have had some success reseating the lamps on projectors especially if they have been moved. NOTE: DO NOT touch the bulb with bare fingers. You could try that. I think you will have a chicken and egg problem. Basically, you can't know that your ballast is good without a certified good bulb and you can't know that you have a good bulb unless you know you have a good ballast... there are no good "bench" tests for ballasts.

My guess with your hours that the bulb is the issue BUT because you have "played" in the power supply, you have left the door open for additional "probabilities" elsewhere... :-(

You could try and find a cheap bulb (doubts) and cross your fingers (PS. if you do, don't claim back to the buyer if it doesn't fix your problem). Because projectors have moved on quite a bit from the 4805, most would just give up and put the money towards an newer projector. Lastly, avsforum has a discussion on projectors (under $2000) and back in their time, 4805 discussion around things like bulbs were common. You might be able to track down some additional "tricks" that might help you out... I haven't looked there in a while cause I moved from a infocus X1 to optoma (refurb) which have both been fine although the optoma is noisy during start up (jingles as the wheel spins up... potential a bearing issue maybe... touch wood it doesn't fall apart).

[bluto]

Re: Infocus SP4805 powers on but no lamp

Hmm I thought you had me convinced that it was the color wheel... (especially since I have ruled out the power supply)?

It definitely does not spin for several seconds after being spun by hand like in this video: https://www.youtube.com/watch?v=hUiYRqrNxxU

In any case unless I can get a parts unit with a good color wheel, this one might be a goner. The various offers for third party replacement color wheels on ebay seem dubious at best.

[budwich]

Re: Infocus SP4805 powers on but no lamp

sorry for the false hope. Basically, I think you have a "used up lamp". The 3000 hours was a HUGE discussion when projectors hit the market place for HT (for all projectors). Basically, there is NO guaranties centered around the number... much like car gas mileage numbers from manufacturers. Its some number that the manufacturer can "show" happened, most likely in "continuous" operation, meaning limited shut down and startup cycles which are the main cause of "depleted hours". The striking is "harsh" on the bulb especially with improper shut down and restarts.

Based on my reads of the service manual, if the unit got to the strike "mode", it has been successful in color spin up but I have never seen my projectors opened up and operating so the visual timing sequence isn't know to me. I guess it could be pretty tight such that the wheel is slow to begin spinning and the software checks on the lamp start up could have its "timer expire" before hand which could mean that it really never attempt the strikes.... maybe... but I suspect not. :-(

PS. the youtube link is pretty good so if your wheel is an issue like those, perhaps indeed the strike timer "programming" may be "falsely identifying" a strike issue versus a bad spin up of the wheel. :-( Its too bad that the cost of these basic components is so high and access to "gently used" is so limited.

[bluto]

Re: Infocus SP4805 powers on but no lamp

Hello again. I am pleased to say that I have finally solved this mystery. I was able to purchase another used SP4085 on ebay for a minimal expense. The one that I got was working but had the dreaded light tunnel burn/discoloration issue.

I first checked my lamp in the ebay unit and verified that it was good. Since I had convinced myself that the color wheel was the culprit, I did a swap of that component first. Unfortunately after doing the swap, the symptoms were exactly the same. The color wheel would twitch and then eventually spin for a little bit but nothing else.

So now I have to swap some more parts. I decided to try both the ebay power supply and rectifier board since maybe mine were cursed. Again the result was the same.

Crap. So now I have to try swapping the main board. I guess this won't be a big deal, maybe there is some calibration for the DMD chip or maybe not. I figure that I will just swap it and hope for the best. Well I couldn't have been more wrong because the ebay main board was an older hardware revision and the connectors to the DMD board were noticeably narrower (fewer pins) than my original.

So now I had to remove the DMD chip and board from the donor optical housing (because it was dusty has a bad light tunnel) and screw it onto my original. That actually too difficult and soon I had the whole thing assembled again.

And the verdict was... Success, it fired up the first time!! The only issue was the donor color wheel was pretty loud. So after one more time dismantling the unit, I put my original color wheel on and again everything worked fine.

So the bottom line here is if your unit won't strike the lamp and the color wheel twitches and eventually spins, you have a problem with the color wheel drive circuitry on the main board.

Final scoreboard on the swap: Original case, optical housing, color wheel, fans and lamp. Swapped in main board, DMD chip & board, power supply and rectifier board.

And for a little post mortum... I got to thinking after upgrading the firmware on the donor main board that maybe the original problem could have been firmware corruption. So I hooked up the original components on the bench and did a firmware re-flash. Thankfully for my efforts, the color wheel twitch was the same. So the issue truly lies in the color wheel drive circuitry.