CurtPalme.com Home Theater Forum

**Curt Palme** · Posted: Tue Jun 17, 2014 1:57 pm Post subject:

**AnalogRocks** · Posted: Tue Jun 17, 2014 2:24 pm Post subject:

mc86 · Posted: Wed Jun 18, 2014 6:11 pm Post subject:

I don't think one has to goto huge expense to remove the air bubbles, though I do agree it should be done with proper vacuum. I just don't know how much. They show 29"Hg with requires a decent and expensive pump. But I wonder if a simple plastic camber (Fisher sci and others sell 5qt plastic vacuum chambers that can go down to 29" Hg for ~$200) could work. If so AND if less vacuum would get 95%+ of the gasses, using a "vacuum generator" one can get to 28"Hg for $65. Again, this *might* be sufficient if held for a little longer or at a slightly elevated temperature (as in 45deg C or so instead of room temp). I dunno. But you could get there for under $250, for sure...and less if you rigged a pressure cooker for vacuum service. The problem with elevated temps and longer time is that although the dissolved gas solubility decreases, the vapor pressure of any volatile compounds also increases. Obviously, one doesn't want to suck out the volatiles with dissolved gasses.

There is a good video of a "for real" setup that shows the degassing process at this smooth-on site. It is same idea.

I have vacuum chambers in my lab that we routinely pump down to 10^-3 torr (1micron Hq) using "roughing" pumps. This is called "low" vacuum. Using a diffusion pump, I go another order or two in magnitude lower. One of our labs uses cryo/turbo pumps, nifty ion pumps and more to go as low as 10^-10 torr. This is called "ultra high" vacuum. Crazy stuff.

Just some quick thoughts. Someone might have done a comparison study showing the bubbles left in clear silicone mold compounds as a function of the degree of vacuum used, but I didn't find it in a quick search.

Cheers,
Matt

zxh398 · Joined: 05 Nov 2009 Posts: 55 Location: china guangzhou

It is difficult to succeed, I use the ERO capacitor has the advantages of small volume high volume capacitance caused by the capacitor with small pitch will seriously affect the insulation level. Vacuum filling is not difficult, I use the South Korean sealing lunch box and ordinary vacuum pump can do, filling equipment cost no more than $200.
Figure is the most complete the repair, Barco EHT, to replace all the capacitance is too complex. The damaged EHT only replacing the damaged 2-3 can work for a long time, EHT would not be 7 capacitors and damage

soleboy · Joined: 27 Aug 2010 Posts: 22

soleboy · Joined: 27 Aug 2010 Posts: 22

Oh my god..

one of my working quad is just failed.
I have to do this repair job.

redfox001 · Joined: 16 Mar 2009 Posts: 2257 Location: The Netherlands

It is Barco bad weather. Let us know if you survive Laughing

jaredjaric · Joined: 05 Jun 2007 Posts: 228 Location: Philippines

jaredjaric · Joined: 05 Jun 2007 Posts: 228 Location: Philippines

**Curt Palme** · Posted: Mon Mar 07, 2016 6:09 pm Post subject:

I am about to throw out two defective ones, if you want to cover shipping, I'll give them to you at no charge. Mind you, I also have a stock of about 20 good working ones now, mostly taken from low hour home theater projectors.

tschaeikaei · Joined: 08 Apr 2013 Posts: 490 Location: Germany/Saarland

I'd use epoxy and a vacuum chamber to prevent from air bubbles.
Cheapo vacuum chamber goes like this: get a refrigerator compressor and an old style glass cheese dome.
Take a piece of kitchen worktop (or any other stiff material) and drill a hole into it.
Connect your compressor from below, place the mold onto the plate and the cheese dome above it.
Some gasket material between plate and dome (rubber or something similar) could help.
There you are. 10 bucks for a DIY vacuum mold chamber.
Those fridge compressors provide a rather good vacuum but don't think you can use it to evacuate projector tubes Very Happy

Best thing is they're usually free and available everywhere.

Regards, Julian

the dude · Joined: 11 Sep 2013 Posts: 179

I agree, a refrigerator compressor would be more than enough! A good one can drag enough vacuum to make water boil. Under vacuum this may happen to more volatile components of the resin, so a medium vacuum may be better.

BTW, interesting stuff Very Happy

km987654 · Posted: Mon Mar 07, 2016 10:02 pm Post subject:

It is surprising that that plastic container withstands atmospheric pressure without leaking or crushing.