CurtPalme.com Home Theater Forum

[tschaeikaei]

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Oh and what would be the best material to use? "Glimmer"?

[gjaky]

The ceramic insulators are much better (in heat conductance) than any of the rubber or mica insulators, though I'm not sure you'll find ceramic insulators in the desired size for the backplane...

[Nashou66]

I used some of the highest CW thermal paste I could find with the existing rubber there. Seems to work well.

Athanasios

[tschaeikaei]

Ok, did you measure delta t between the hottest transistors and the heat sink?
I measured 61°C on the hottest transistors vs. 42°C at the heatsink 1 or 2 cm away,
when the projector was running 1080p for 45min.
Original mounting and heat conducting.
Regards, Julian

[Nashou66]

[tschaeikaei]

Hmm, 4°C would be an improvement, but not that much.
Which thermal grease did you use?
I'd suggest this:
There are many TO220 transistors (with the metal plate) and smaller ones without metal plate.
The smaller ones could be directly mounted to the heatsink without the silicone stripe but with thermal grease.
The To220 should be isolated by a (better) silicone material and be mounted maybe with thermal grease.
?

[Nashou66]

[tschaeikaei]

Yes, sure, i understood that the same way you tell it.
But think again: If the heatsink is 4°C cooler with the modified cooling system (i assume you didn't add a fan on one projector),
the components have to be hotter.
I would recommend to measure directly at the components (they don't get equally hot) and compare with the heatsink temp.
I measured with the tiny temp-probe of my DMM, which is easy to use on small areas- might be better than a IR thermometer.
As i said: Many of the transistors are about 42-45°C, SOME are 60-62°C. The hotter are the interesting ones.
I did not look up what the are used for, but to keep the projector stable, it would be the best, if they are all the same temperature.
That tells us that the thermal coupling is good.

But back to the original question:
What material should be best to electrically isolate AND thermally couple ( if necessary in addition with the MX-4) the transistors to the heatsink?

Regards, Julian

[gjaky]

[tschaeikaei]

Thanks to gjaki, i've read that some time ago and whats most interesting:
A fan MUST push air on a heatsink, if it sucks the air, cooling efficiency is about the half or so.

But another thing that i've learned: You know, these projectors of mine are HD8B equipped (no color correction)
and have fast green phosphor.
When i switched from white to silver screen, i noticed (apart from the higher brightness) that the colors get much better.
I have deep and sexy reds, much greener greens (the look yellowish on a white screen) and much more vibrant colors over all.
The current (temporary) setup is like the following:
Single projector on silver screen (one axis curved), picture width about 3m (9,85ft).
Brite 50, Contrast 60, G2 in the 68-70 range.
Perfect brightness to watch movies in the darkened room.

My 9PG in the other room projects on a flat white screen, has color corrected lenses and normal phosphor.
I use this one as a reference. I can't see a difference in colors.

So if someone wants to use my experience: If you have fast greens and/or uncorrected lenses:
Don't tint the glycol, dont buy other tubes. Feed it with 72Hz vertical (because the fast tubes tend to flicker)
and go for a silver screen. I use the cheapest material i could find.
http://www.stoffamstueck.de/shop/themen2/technische-gewebe-zeltstoff/polyester-leinwand-silber-beschichtet.html
And trust me, i have tested so many sample materials, aluminum paints and so on.
This is the best solution so far.

Regards, Julian

[tschaeikaei]

Hey guys, another question.
"My Marquee seems broken to go" should describe it.
One of my 8500 Ultras behaves strange on power up. Sometimes i need to press the power button on the remote twice or more.
The relays are audible every time i press power, but in most of the cases its necessary to press power more than once to get High Voltage
and a picture on screen.
I could go with that, but yesterday it powered up after multiple pressing of the button and said "complete reinitialization successful".
Thats something i can't stay with. Luckily i am only experimenting with it at this time and did not loose a time-consuming setup.
Did anyone experience something like that in the past?
I must say that the projector is only roughly plugged together, not all ground straps are connected.
Hardware setup mode, you know...

By the way, i think this is the last and best working fan mod so far. I'll take a picture of it.

Regards, Julian

[tschaeikaei]

Hey, just cause i'm in a bit of a hurry. I want to put the projector together again.
But is have no idea why it does this strange complete initialization on it's own.
I've taken the processor board out. The Renata cell has 3,05V, which seems ok for me.
Does anyone have a hint on that problem?

Regards, Julian