Magnavox RPTV

It's not that entailed to pull the tubes. Four 1/4" screws on the frame, pull the kine board, disconnect the deflection yoke plug and the convergence yoke plug from the front and pull the ground wires free. Just did one of that vintage last week, PTV382 and took about an hour that way to do the green and blue. I've never had to do the red since, for whatever reason, red never seems to 'activate' the bacteria. Take the expansion cup off, unscrew the cap, make sure you don't lose the O ring, drain, take apart, clean with denatured alcohol, dry and put together and refill. Make sure you don't underfill and just fill to the base of the cap. May sound like alot of steps but, if you don't try to clear all the bacteria, you're just wasting time and money and will be back in in a couple of months.

I'd have to agree on pulling the tubes. I've got a PTV300 set that I just changed the fluid in. I rinsed everything out with Windex and put fresh fluid in. Followed the CRT replacement procedure (minus removing the yoke). Afterwards, I adjusted a few of the tabs on the CRTs to bring them back into alignment and tweaked a couple of pots on the convergence board. At least on my set, the user convergence board has a push button switch that brings up a crosshair. I used that to align each of the guns to green and then by using DVD cases to block two of the lenses, used the focus and screen controls to get a clear crosshair of each color with a solid black background. This meant looking at the screen from the back and then moving around to the front for final focus and screen settings.

The hardest part was getting the nerve to do it. If your set still has the paperwork for the convergence board, it should be pretty simple to touch up anything that changes. Each of the pots has a specific function. My picture isn't perfect however it's great compared to what it was: dark and red. I have a slight misalignment at the top right that is only visible on the DVD menu screen. Probably won't mess with it...

Denatured alcohol sounds good as a cleaner. I'll try that next time. I have a friend with a PTV325 set with a fuzzy picture. If you want new CRT gaskets and fluid, Matt Electronics has kits with new gasket and fluid for about $13 each. Got my fluid from MCM Electronics; slightly more than one

The fluid in my CRT chambers wasn't terrible; just the color of cider vinegar. Like watching TV through sunglasses... Blue and green were the worst and had the most buildup on the CRT face.

yourself'.

Thanks to both of you for responding. I'm still weighing my options, since the set has a pretty good picture as it is. I will definitely be doing at least the blue tube, since it is the one with visible gunk on the face.

It sounds like I should probably at least change the fluid on the red tube as well. That was a question I asked earlier, which my isp lost due to a usenet foulup. It sounds like the fluid, even absent any contamination, changes color. That would account for the slightly yellow or amber tint that I've seen on many older RPTV's with otherwise reasonable pictures.

jak

The yellow tint is usually due to lack of blue. In addition to the bacteria/algae thriving on blue light, the blue phosphor is the least efficient, so it is driven harder and burns out faster. The red tube is the least likely to have coolant contamination.