Samsung HLT-4675 DLP Shutting Down..

[mmartell]

Calling R J.. lol

I tried GIVING this set away but alas the damn thing came back to me. Starts and runs fine for about 10-20 minutes then the lamp goes out and set tries a couple times to restart it then shuts down with three flashing lights.

If I let it sit for a moment it fires back up but for a shorter period this time before shutting down again. Thought at first was the lamp so replaced that but same thing. Seems heat related but all caps look ok.

How does one troubleshoot as to whether the DMD, colour wheel or ballast/ps is the issue (or lamp for that matter) ?

[R_J]

Re: Samsung HLT-4675 DLP Shutting Down..

I don't have that exact manual but all 3 leds flashing (Optic chassis may be defective)
How is the picture before it shuts down?, usually if its the color wheel acting up the picture tint (phase) will change. especially the reds. I hav'nt seen too many intermittent ballasts, but it could happen.
[been a long time since I've worked on these]
The lamp could cause this, you would need to sub in a known good lamp.
Same for the dmd, hard to determine if its intermittent without subing it out, put usually if it was bad you might see pixelization, or something like that before it goes out.
You say you tried a different lamp, but is it new or used?
One more thing to check are the connetions for the color wheel to the dmd board, I have seen those go bad, poor solder connections.
There is not much information about these sets,

[mmartell]

Re: Samsung HLT-4675 DLP Shutting Down..

It's a new replacement from eBay but it's, gulp, chinese or wherever these knockoffs come from. But I figure with the same symptoms it's *likely* not the lamp.

I was thinking I could monitor a pin or two to see what voltage drops out when the lamp kicks off to determine where the fault lies but don't understand the nature of these beasts well enough to know where to probe. Is there a self-diagnosis in the set ? When I turn the set on again I could go into the Service Menu if need be...

I will run it again tomorrow and check the pic as it fails and follow up then. Thanks.

[R_J]

Re: Samsung HLT-4675 DLP Shutting Down..

Does this set have a temp sensor on the top of the lamp? it looks like the picture and has 2 wires going to it, you could jumper it (short it out) and see if thats causing the problem, but that usually gives an over temp error.
The ballast has 2 connectors, one has 2 large wires with high dc voltage (around 380vdc)
and a low voltage control plug 3-5 small wires, there should be +5volts on one of the wires when the balast is on, if those voltages stay the same when the lamp goes out then it could be the ballast.
If that control line turns off when the picture goes off then the dmd is telling it to shut off for some reason.
If the color wheel stops giving a feedback pulse to the dmd it will think the wheel stoped and turn the lamp off.

[mmartell]

Re: Samsung HLT-4675 DLP Shutting Down..

That's exactly the type of info I'm looking for.

I messed with this a while ago. I know I've already shorted the door switch (door is missing!). Not sure about the temp sensor though I'm pretty sure I have it. Will take a look.

[mmartell]

Re: Samsung HLT-4675 DLP Shutting Down..

Ok gave it a test run without probing any voltages or such and the lamp shuts off without any warning or video degradation. The audio plays on for maybe ten seconds then stops and the lamp attempts to strike a couple of times before I hear the colour wheel wind down and the set shut off.

[mmartell]

Re: Samsung HLT-4675 DLP Shutting Down..

Actually the set doesn't shut down it goes into some sort of sleep mode with the three lights flashing. Pressing the power button initiates the shut down melody and actual power off.

This time I noticed a humming that was audible about ten seconds before the lamp went out. Colour wheel maybe ?

[mmartell]

Re: Samsung HLT-4675 DLP Shutting Down..

Nevermind, the symptoms seems so erratic I think it's why I tried to just give the damn thing away lol.

I'm going to monitor the 5v line at the ballast to at least attempt to narrow it down.

[R_J]

Re: Samsung HLT-4675 DLP Shutting Down..

How was the picture before it quit, did the color/tint change, It could be the color wheel, I replaced one for a friend that was intermittent, I thought I could lube it (sometimes works) to get it going but it was the air bearing type, the problem with his was the flat ribbon that drives the 3 phase motor was brittle and cracked.
The flat ribbon drives the motor, the plug with individual wires is from the photo interupter (pulse/tach) for the color wheel.

[mmartell]

Re: Samsung HLT-4675 DLP Shutting Down..

Didn't notice a change in the pic before it went out. I've taken out the color wheel and given it a spin and it spins freely but there is an audible sound I didn't expect to hear. Is that normal ?

I'm going to run the set with the wheel out of the engine (hope it doesn't explode ) just so I can see it in action.

[mmartell]

Re: Samsung HLT-4675 DLP Shutting Down..

RIP rear dlp, may you dream in 3lcd or something blah blah...

I killed it. I ran it with the color wheel facing up waiting for it to fail so I could maybe rule out the color wheel but smoke began to rise from the light tube and by the time it was all over there were some melted pieces in there. Didn't realize the wheel itself provided some cooling effect from the lamp.

I will have a look later to check on the extent of the damage but this just lightens my load actually. Almost can't wait to haul it to the curb hehe.

[stj]

Re: Samsung HLT-4675 DLP Shutting Down..

if i had space, i'd like to try an led conversion on a dlp projector - just for fun.

[mmartell]

Re: Samsung HLT-4675 DLP Shutting Down..

As in an led lamp in place of the stock lamp ?

[stj]

Re: Samsung HLT-4675 DLP Shutting Down..

as in RGB-LED inplace of the lamp & disc.

although you could just dump a high power led in and keep the disc.
big leds generate a lot of heat, so you would need to mount it on a heatsink - probably a p4 / athlon type one on it's side.
then duct the existing fan to blow through the sink.

this is THE place for info on anything you could class a "lightsource"!!!
http://www.candlepowerforums.com/

[R_J]

Re: Samsung HLT-4675 DLP Shutting Down..

The color wheel does not provide any cooling, I'm not sure what smoked, I've seen them run with broken color wheels and not had any problems other than no color of course.
After the lamp there is a uv filter, then the color wheel, then the light tunnel (4 small mirrors aranged in a square (tunnel), then some lenses, mirrors etc.
Did you have a picture with the color wheel out?

[mmartell]

Re: Samsung HLT-4675 DLP Shutting Down..

Well the whole assembly was out and facing backward with everything plugged in but I could see a pic as it reflected off the various surfaces behind the tv, yes.

It looked like whatever is just past the color wheel assembly was smoked. Will attempt a picture when I get home.

[stj]

Re: Samsung HLT-4675 DLP Shutting Down..

The color wheel does not provide any cooling, I'm not sure what smoked, I've seen them run with broken color wheels and not had any problems other than no color of course.
After the lamp there is a uv filter, then the color wheel, then the light tunnel (4 small mirrors aranged in a square (tunnel), then some lenses, mirrors etc.
Did you have a picture with the color wheel out?

you wont get all that in the cheap no-name ones on ebay.
i stripped one.

starting at the rear:
mirror
lamp
lense
disc&lcd assembly
space (for air to pass across from a side-fan)
final output lense.


i'v also stripped a newer one that was the same - but colour display & no disc.

[mmartell]

Re: Samsung HLT-4675 DLP Shutting Down..

And evidence of the carnage... first one is top-down second one is straight on with lamp assembly removed.

[R_J]

Re: Samsung HLT-4675 DLP Shutting Down..

Looks like the light tunnel heated up. I've never seen that happen, how long did you have it running before that happened. The only thing I can think of is that the color wheel glass itself must filter the intensity enough so the light tunnel does'nt get that hot?

[R_J]

Re: Samsung HLT-4675 DLP Shutting Down..

you wont get all that in the cheap no-name ones on ebay.
i stripped one.

starting at the rear:
mirror
lamp
lense
disc&lcd assembly
space (for air to pass across from a side-fan)
final output lense.


i'v also stripped a newer one that was the same - but colour display & no disc.

I have no idea what this is about? I was just saying what components were after the lamp in the light path.