8mm Forum: DLP TV shutting down

This is topic DLP TV shutting down in forum General Yak at 8mm Forum.

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Posted by Jim Schrader (Member # 9) on March 19, 2016, 11:04 PM:

I got one of these from our neighbor for free it's a magnavox dlp rear projection tv it has worked great up until last fall when I turn it on it stays on for a minute then the whole system shuts down then it turn on the power and repeat this 6-9 times before it stays on I have replaced the bulb twice the ballast and the power board anybody with experience like Steve have an idea as to what to try next.

Posted by Steve Klare (Member # 12) on March 21, 2016, 04:10 AM:

Hi Jim,

I sounds something like a cooling fan is a little sticky and until it gets up to speed there isn't enough cooling air and the TV is going into thermal shutdown to protect itself.

Fans are basically the worst part of many electronic systems for operating lifetime: very often they are the only moving parts inside and the only thing subject to wear and tear.

While you are in there please clean out dust and other blockages to cooling air (dirty fan filters?). Even a healthy fan can only do so much if the thing is congested!

If it was something more modern I'd be tempted to call it "firmware". This is nasty because basically it's the results of somebody else's thoughts (-things don't "function", they "behave"!) and it starts to become almost a matter of psychology.

-the one good part of it is I don't work on that and when it happens to me I get to send it back to the programmers!

Posted by Brian Fretwell (Member # 4302) on March 21, 2016, 04:27 AM:

Yes I had trouble with a cooling system that was traced to the air inlet grill being blocked with dust and possibly my theatre club's LCD video projector had the same trouble with its air filter.

Posted by Jim Schrader (Member # 9) on March 21, 2016, 03:33 PM:

It did do that in the summer it shut down and I noticed the inlet/outlets were blocked by dust once I cleaned them out it worked fine. This latest incident started last fall I see the exhaust fan spins and the fan under the bulb is also spinning. Is there a certain speed these should be spinning? Fast medium slow?

Posted by Steve Klare (Member # 12) on March 21, 2016, 03:49 PM:

It's hard to say really: the real answer is "fast enough".

-but when is "enough" enough?

(Then again, isn't "enough" always enough?!!)

One thing to check for is the sound of the fans. They will get louder as they fail.

Posted by Jim Schrader (Member # 9) on March 21, 2016, 04:51 PM:

I can hear one or both of them working they speed up when needed. I was told to check voltage from the ballast (which comes from the power board) to see what the voltage was I got a reading of 311v and was told it should be 360-380v but don't get that when its warmed up and stays on its definitely a cold starting problem.

Posted by Jim Schrader (Member # 9) on March 21, 2016, 06:26 PM:

I checked the fan under the lamp to which it was spinning last time I checked this time I stuck a mirror underneath to see it spin and it was dead, so then I had to get to the lamp housing the get at the fan it was a challenge but got it out ordered 2 fans that were close to the original as I could find I did have to splice and solder the old end on to the new one hooked it up temporary to see if it would spin and sure enough it did so I put it all back together and put the lamp back in and turned it on and waited for it to go off.......it stayed on 😀 Now that I got that fixed its a good feeling thanks for all your inputs Steve was the closest with his diagnosis thanks.

[ August 19, 2016, 12:51 PM: Message edited by: Jim Schrader ]

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