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NFT: Repairing a circuit board

Bramton1 : 9/2/2015 9:20 am
Last spring, my uncle gave me an old Dell digital projector, which I've been using in my school library. I already have a school projector mounted to a smartboard for instructional use. I've used the Dell projector to project images onto the wall space, which I've then penciled and painted onto the wall. It's really livened up the otherwise bland teal wall space.

Unfortunately, the projctor seems to have kicked the bucket. When I turn the projector on, it tries to fire up the lamp, failed, and tries again three more times before quitting. I replaced the bulb with a new bulb my uncle gave me, but the problem persists.

Dell's policy on projectors is they replace them when under warranty, but offer no service or parts when out of warranty. They will also not provide service manuals or schematics. I guess they would just rather drop hundreds or dollars on a new device. There are independent businesses that repair Dell projectors, but that will probably end up running me $300 or more.

So with nothing to lose, I'm considering attempting a repair myself. I have repaired my PS3 motherboard from the YLOD, so I have some experience (although that was mostly about cleaning the board and reattaching loose chips). Ultimately, I see this as a opportunity to learn something new and maybe fix the projector in the process.

So I opened the projector, removed one of the circuit boards and visually inspected what I could for any obvious problems, and researched what I could online. I think the problem could be related to a bad capacitor or something else on the circuit board.

So here are my questions (finally).

1. I know that you can't test a capacitor with a multimeter while still attached to a circuit board, and I know some of the telltale visual signs of a bad capacitor. But short of seeing any of these obvious signs, is my only option to remove each capacitor with a soldering iron, test each capacitor, then re-solder the good ones back and replace the bad ones?

2. Some of the circuit boards are attached to each other (to to other components) with wires attached by screws (easy), pins (easy), and ribbons (easy). Many others are attached by connectors that aren't designed for easy detachment (I assume you would have to remove the individual wires from the connector). What is the most efficient way of disconnecting/reconnnecting these?
Bramton  
Sarcastic Sam : 9/2/2015 9:23 am : link
Could you post a picture of the questionably bad capacitors? Usually it is very obvious when one goes bad.
And this isn't a hard and fast rule  
Sarcastic Sam : 9/2/2015 9:26 am : link
but usually the caps that blow are the electrolytic ones (the cylindrical towers with the stripe) that are used for power protection and conditioning. These usually aren't buried.
Sam  
dorgan : 9/2/2015 9:30 am : link
is correct on both counts. Look closely at all those tower capacitors. Odds are you'll see a little swelling in one or more of them. Sometimes, the swelling is subtle, but if the end is not perfectly flat, they're the culprits.
Not typical for the caps to go on projectors  
jcn56 : 9/2/2015 9:34 am : link
but if you do suspect them, you're better off just replacing to see if it works than you are trying to test them. The trouble associated with testing is barely less than replacement.
Also - have you done a Google search against  
jcn56 : 9/2/2015 9:35 am : link
the model number to see if people suffered similar failures, and what the resolution was for those who fixed them?
RE: Also - have you done a Google search against  
Bramton1 : 9/2/2015 10:11 am : link
In comment 12448462 jcn56 said:
Quote:
the model number to see if people suffered similar failures, and what the resolution was for those who fixed them?


I have searched for similar issues. I found a Dell forum post with the exact same model projector (dell 2200MP) and the exact same problem, but no resolution.

http://en.community.dell.com/support-forums/peripherals/f/317/t/18009284

The next best thing I found was a basic repair video on YouTube for a similar model. It's not the same issue as mine (their's was completely dead), but it clued me in that there is some kind of issue communicating with the lamp.

https://youtu.be/nyG1p7AH0kE

I don't think it's a total failure, because if you plug in the projector without the lamp installed, the led doesn't light up at all. When you plug in the projector with the lamp installed, the led lights up and blinks (which is normal). So the projector can definitely tell when the lamp is installed. As this is an issue with two different bulbs, I suspect the problem is either a component in the circuit board, or the wiring to the lamp.
RE: Bramton  
Bramton1 : 9/2/2015 10:13 am : link
In comment 12448431 Sarcastic Sam said:
Quote:
Could you post a picture of the questionably bad capacitors? Usually it is very obvious when one goes bad.


I will post a few pictures, although I probably won't get a chance to open the projector back up until tomorrow. I already planned to take pictures, because without a service manual or schematics, I need to document exactly how I took it apart so that I can reassemble it correctly.

I'll post some of those tomorrow.
Okay - going to miller this thread a little...  
Dan in the Springs : 9/2/2015 10:19 am : link
my key fob went out and I pulled out the circuit board to inspect. A magnified visual inspection revealed no hairline fractures or obviously loose parts. The side of the board however appears to have broken just a little bit, and I don't have the piece that broke off. This little piece has no apparent electrical value, but I'm thinking it is keeping the board from aligning properly.

Anyway - I was thinking about trying a fix as new keys run over $300, and was considering the linked solution to build out the part of the board that broke off. Any of you experts have thoughts about this solution?
Bondic replacement plastic - ( New Window )
RE: RE: Also - have you done a Google search against  
jcn56 : 9/2/2015 10:31 am : link
In comment 12448540 Bramton1 said:
Quote:
In comment 12448462 jcn56 said:


Quote:


the model number to see if people suffered similar failures, and what the resolution was for those who fixed them?



I have searched for similar issues. I found a Dell forum post with the exact same model projector (dell 2200MP) and the exact same problem, but no resolution.

http://en.community.dell.com/support-forums/peripherals/f/317/t/18009284

The next best thing I found was a basic repair video on YouTube for a similar model. It's not the same issue as mine (their's was completely dead), but it clued me in that there is some kind of issue communicating with the lamp.

https://youtu.be/nyG1p7AH0kE

I don't think it's a total failure, because if you plug in the projector without the lamp installed, the led doesn't light up at all. When you plug in the projector with the lamp installed, the led lights up and blinks (which is normal). So the projector can definitely tell when the lamp is installed. As this is an issue with two different bulbs, I suspect the problem is either a component in the circuit board, or the wiring to the lamp.


I don't think there's any real 'communication' with the lamp - it does an open circuit check to make sure it hasn't burnt out or wasn't installed properly, but that's about it.

If I had to take a stab in the dark, I'd suspect the DLP chip is having problems. I know TI had some issues and lead to recalls that affected some Dell units, but I don't know if this one falls into that age range (seems a bit old for that).

Needless to say, if I had to try a blind repair, I think I'd try reflowing the board or the DLP chip. If you can get the board free, you can stick it in a moderate oven for a little while (be sure there are no plastic components, they'll melt). If there are plastics, you can use a hot hair dryer to run some hot air over the DLP chip and hopefully get it back up and running.
RE: Okay - going to miller this thread a little...  
Sarcastic Sam : 9/2/2015 10:36 am : link
In comment 12448549 Dan in the Springs said:
Quote:
my key fob went out and I pulled out the circuit board to inspect. A magnified visual inspection revealed no hairline fractures or obviously loose parts. The side of the board however appears to have broken just a little bit, and I don't have the piece that broke off. This little piece has no apparent electrical value, but I'm thinking it is keeping the board from aligning properly.

Anyway - I was thinking about trying a fix as new keys run over $300, and was considering the linked solution to build out the part of the board that broke off. Any of you experts have thoughts about this solution? Bondic replacement plastic - ( New Window )


It's OK if the board isn't completely secured *as long as* the button for the fob is in the right place. My uneducated guess would be that when you press the button, the loose connection on the circuit board prevents proper mechanical contact to close the switch.

I haven't used what you linked, but I've had a lot of success with little repairs using sugru.

http://www.amazon.com/Sugru-Self-Setting-Rubber-Black/dp/B00KX6LTYM/ref=sr_1_4?ie=UTF8&qid=1441204558&sr=8-4&keywords=sugru&pebp=1441204563591&perid=1Z8BVA3SNH68K5SV8SQQ

And if you buy using BBI's Amazon affiliate link, he gets a portion of the proceeds!
Thanks SarcasticSam...  
Dan in the Springs : 9/2/2015 11:47 am : link
actually, what happens is that the fob sends and receives a series of infrared signals to the Electronic Ignition System, allowing the car's ignition system to work correctly. Intermittently the system fails with this key fob, and I think that what's happening is that broken board causes a misalignment from time to time and the signal is interrupted.

This function is powered on the fob by an induction coil. I also think it is possible that the slipped board could cause the power system to fail as well.

Either way, it seems that the only chance I have of fixing the fob would be to fix the board. I check the Sugru stuff out too.

Thanks!
Any time I have problems like that with small electronics  
jcn56 : 9/2/2015 11:50 am : link
and alignment, I turn to my old pal epoxy. It's a one-time fix, and you have to get it right the first time, but if you do it tends to work for a very long time. Of course, if it leaves you unable to do battery changes, that's out.

Another consideration would be trying to find a housing or broken FOB on eBay, and using the housing there as a replacement.
I've heard  
I Love Clams Casino : 9/2/2015 12:49 pm : link
that connections can open and cause a void when temperatures are enough to weaken the joint (soldered, I assume) causing a shutdown and then fuse back together once the unit goes cold again.

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