CurtPalme.com Home Theater Forum

wallace123456 · Joined: 14 Aug 2006 Posts: 2236 Location: Northwest VA area

A while back, I noticed the bottom plate on my nec 6pg xtra was like really hot. Well, I used a meat temperature gauge and measured the plate to be about 131 degrees.

Is this too hot? Seems like it is to me, but... Confused

wallace

garyfritz · Joined: 08 Apr 2006 Posts: 12088 Location: Fort Collins, CO

Yes, I'd say that's too hot. It means the hot components inside are a lot hotter than that. Internal temps of 120F or less are better. You should consider improving your ventilation. Is it ceiling-mounted? You could do the "plenum extraction" technique.

jask · Joined: 17 Mar 2006 Posts: 10187 Location: kamloops BC

way too hot! that will kill electronics. better quality caps are rated to 110 degrees in these old units and the cheap ones are 85 degree.

wallace123456 · Joined: 14 Aug 2006 Posts: 2236 Location: Northwest VA area

stefuel · Posted: Fri May 08, 2009 2:37 am Post subject:

Make sure the bottom is clean. The whole bottom is one big heat sink. Most of the temerature is coming from the STK chips fastened to the base. Make sure the inside is clean and not loaded with dust. I used to have a PG Plus. I had found some large heat sink material and just set it on the base over the STK's with heat transfer grease between. It helped alot.

draganm · Joined: 08 Mar 2006 Posts: 8990 Location: Colorado

wallace123456 · Joined: 14 Aug 2006 Posts: 2236 Location: Northwest VA area

Heywood Jablome · Joined: 12 Mar 2006 Posts: 1548

My answer to the OP's question posed: Any of Emdawgz' avatars Wink

I'm with Chip on the heatsink idea... I salvaged two large sinks from an RPTV that went to scrap, probably 2.5" x 6", aluminum finned. I had to spot-drill clearance holes where the fasteners came thru the base plate and then simply adhered the sinks to the outside of the plate with heatsink grease.

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

This was one of the main reasons that RPTV manufactures had a bulletin to upgrade the STK's to a different chip. The originals couldn't handle the current and would over heat. The upgrades had a higher current rating and would run cooler.

Also your convergence adjustments need to be as close to neutral as possible. If a basic adjustment is off then a later adjustment has to be more corrective and will cause the chip to work harder and run hotter.

**kal** · Posted: Fri May 08, 2009 3:07 pm Post subject:

Asking "How hot is too hot?" can't be answered. It's not black and white. Keep it as cool as possible and it'll last longer and run a lot more stable.

The cooler you run it, the longer it'll last. Capacitors rated to 110F will still last longer if you run then at 80F instead of 100F. Just because they're rated 110F doesn't mean that you should run them that high.

I see a lot of people do fan mods and other things and then say that their temp is only up X number of degrees and that it's "still within spec". Sure, it's within spec, but you're running it in to the ground faster. Just because you run it for a few days at the hotter temperature and nothing happened doesn't mean that you aren't killing it faster - you are!

Kal

garyfritz · Joined: 08 Apr 2006 Posts: 12088 Location: Fort Collins, CO

Mounting a heatsink to the outside of the baseplate, where it's hottest, is a good idea -- as others have said, the PGs use the baseplate as a heatsink for the STKs and you can improve the heat-dissipation effectiveness by adding a bunch of fins.

Improving airflow through the chassis is a good idea too, which is what the plenum extractor is for. If a PG is like an XG, there are two side fans that you might want to reverse. (They blow out by default, which works OK for table mounting, but for ceiling-mount with extraction, they blow the wrong direction.)

See e.g. http://archive2.avsforum.com/avs-vb/showthread.php?t=529823 for some pix of a plenum extraction system. He just taped an aluminum lasagna pan Smile

to the baseplate, and tape an extraction duct to the pan. The pan just lets the duct suck air out of a larger area -- covering all/most of the holes in the baseplate.

From your pic it looks like you don't have any kind of venting or ducting to remove hot air. True? If so, how hot does it get at the ceiling when the projector runs for a while? When I first installed my XG, without any ducting, the room heated up really fast. On "opening night" I had 8 people in the theater (equivalent to another 800W heater), and before we even finished the movie, the XG overheated and shut down. It was WAY hot up at the ceiling, and the baseplate/heatsink was almost too hot to touch. Adding a duct to remove hot air from the room made a BIG difference, and sucking the hot air out of the XG chassis improved it even more.

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

A STK392-110 has a maximum operating temp of 125C or 257F.

Now ask me if I believe that....... Laughing

Or maybe it just means that's the temp when it explodes....... Shocked

jask · Joined: 17 Mar 2006 Posts: 10187 Location: kamloops BC

draganm · Joined: 08 Mar 2006 Posts: 8990 Location: Colorado

**AnalogRocks** · Posted: Fri May 08, 2009 4:00 pm Post subject:

C'mon Jask, you should be bi-lingual. Metric and American.

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

they are usually spec'd hour wise for capacitors, that data sheet does not say hours of use at that temp, i guess it is just assumed?

If you need replacing them i guess most use the STK392-180 as a newer chip replacement, it has a higher wattage from 11 to 18. In mitsu CRT sets it works fine as a replacement.

Athanasios

stefuel · Posted: Fri May 08, 2009 9:55 pm Post subject:

The only problem I ever found with the original STK392-140 was that they ran so hot that the pins would unsolder inside the chip. They usually fall out of the chip when you are replacing them. A quick test if you think you are having a problem is to press lightly on each pin with a pencil eraser while it's running and look for changes on screen. Also be aware that there was a aftermarket version of these chips that $ucked big time. The only thing they were good for was taking them to a pond and see how many skips you could get from them before they sank Rolling Eyes

Brian Hampton · Joined: 22 Apr 2006 Posts: 1173

Grrr,....

I'm scrolling down waiting for the reply button to show up when I see someone beat me to it...

Quote "My answer to the OP's question posed: Any of Emdawgz' avatars "

-Brian