Hi All,
How do I know it is time to change the glycol? I have an Ampro 4600 and I am certain this was never done. Low hours but it is 14 -15 years old. The picture looks great but I see some yellowing on a white background. Mostly at the sides of the screen. Also the picture does not have as much punch as I think it should. Old Glycol?
Thanks, Don

Pull the lenses and take a look, if the glycol is cloudy or not clear you should replace it.

Thanks Fellenz I will have a look. Do you think my problems could be caused by this?
Best, Don

It is possible it is the glycol as I am assuming this is a liquid coupled set. If so there is more glycol between the tube surface and the lens on the edges which would account for the yellowing your are seeing at the edges. The only way to tell though is pull a lens or two. At the age of your set wear and other factors could also play a role.

Edit: The worse glycol I ever saw was NIB Ampro retro 8" tubes. That glycol was nasty and was only 5-6 years old at the time I had those tubes.

Thanks Secstate,
It's the glycol. I will order some up. I have read a bunch of great info here, (from Curt among others), about this. I will pop an email to Walter Allen at Elite Video who has been a great help in the past. My main question is can I do this without pulling the tubes? I read the Ampro service bulletin on this, but I am starting to go beyond my comfort zone when words like implosion, face shield and high voltage come up in the first sentence. Sounds like I may need o-rings for the c-elements and fill plate gaskets anyway.
Thanks again, Don

No, pull the tubes. I have actually re-glycol-ed Ampros by putting the sets face up, removing the C element and draining and refilling, but if you splash some glycol around, you risk nuking a board or two. Best to pull the tubes out. It's not that hard to do.

Thanks Curt.
Best,
Don