Magnavox RPTV
jakdedert
tweaking; clean mirrors, lenses, screen and tweak user convergence. The
green gun was intermittent, but following advice here, I found and fixed
a bad joint on the CRT neck board.
The blue crt has the usual contaminated cooling fluid, which I intend to
address next (Green has a few floaters, red seems clear...I'll do them
all, one at a time to chart the improvement.)
My question concerns coolant change advice on the internet; which ranges
from 'suck out the fluid, replace after cleaning through the diaphragm
hole', to: 'completely remove each CRT, disassemble, clean, reassemble
using new O-rings'...from easy DIY job to 'don't even try this yourself'.
Is there a middle ground? It doesn't look real easy to clean all that
gunk out using remote tools; but pulling the guns, even one at a time,
just looks way too involved (sort of like laproscopic surgery). I'm
leaning toward sucking out the fluid, removing the lense assembly and
cleaning with the tube in place; but even 'that' looks to require quite
a bit of cabinet disassembly. The back two screws on the lenses are
under a cover which (I think) I need to remove the back of the set, or
the else mirror, to access.
Any thoughts? The tubes themselves seem to be in good shape. The set
might not have gotten a lot of use...plenty bright.
The only other issue: the brightness control seems to have little or no
effect on the picture. All controls were set at midrange when received,
and tweaking yields little improvement.
Thanks in advance
jak
Tech Data
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.
Kirk S.
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
24 oz can was enough for all three CRTs.
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.
Kirk S.
"Tech Data" <tvd...@gmail.com> wrote in message
news:1149471813.0...@i39g2000cwa.googlegroups.com...
jakdedert
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
Bill S.
jakd...@bellsouth.net says...
> 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.
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.