Projection CRT Coolant Leak

[Chris F.]

Got this massive RCA projection set (CTC-195 chassis) in the other day,
the initial symptoms were a badly-shrunken raster and an inability to change
the channels or adjust volume. Once I got inside I noticed some strange
corrosion in a couple of places, and realized that some coolant had leaked
out of the blue CRT and dripped onto the board. The spill wasn't too bad,
and after cleaning up the board the set appears to work. The problem is that
the blue CRT has lost at least some of its coolant, and there's a risk that
more may leak out in the future. The leak seems to be around the edge of the
CRT, like it just wasn't sealed properly. There are two things I now need to
know:
1. How to add coolant, and what amount to add. These CRT's have an odd
rubber button on the side, it looks like the primer bulb on a lawn mower
engine - I'm guessing these are involved in the procedure.
2. How to seal the leak - is common silicone sealant good enough?
Thanks for any advice.

 

[TOM1954]

  Got this massive RCA projection set (CTC-195 chassis) in the other day,
the initial symptoms were a badly-shrunken raster and an inability to change
the channels or adjust volume. Once I got inside I noticed some strange
corrosion in a couple of places, and realized that some coolant had leaked
out of the blue CRT and dripped onto the board. The spill wasn't too bad,
and after cleaning up the board the set appears to work. The problem is that
the blue CRT has lost at least some of its coolant, and there's a risk that
more may leak out in the future. The leak seems to be around the edge of the
CRT, like it just wasn't sealed properly. There are two things I now needto
know:
1. How to add coolant, and what amount to add. These CRT's have an odd
rubber button on the side, it looks like the primer bulb on a lawn mower
engine - I'm guessing these are involved in the procedure.
2. How to seal the leak - is common silicone sealant good enough?
Thanks for any advice.

Long procedure if you are not familiar. The crt has to be removed
from the chassis to determine if any coolant leaked onto the HV anode
lead and caused subsequent arcing. If not, crt has to be disassembled
and and drained and cleaned, lens crt face, etc. Generally, it will
be close to a bottle of new coolant to refill. Once it is reassembled,
coolant is added through the "Primer Bulb" refill hole, making sure
not to allow air bubbles to be introduced. Auto type sealant is
adequate, allow 12-24 hours to dry and make sure no leaks before re-
inserting crt into chassis. At that point you will have to enter the
service mode and re-converge blue crt to the other 2 crt's. Good
Luck.