I have nearly replaced all the paper capacitors. I have gathered from an earlier thread that there are paper capacitors masquerading as mica look-alikes which should be changed.
I examined some of the paper capacitors for leakage and they are all bad! What is worse is when they are heated: I tried applying a little heat at the leakage increased at an alarming rate. Maybe I could use them as a temperature sensor in a thermometer.
Boy, RCA must have really skimped on quality to keep the cost down!!!
I checked the electrolytics again and they have remained good apart from the additional Canadian Mallory 80mfd units for the 25Hz modification. These capacitors have become very leaky again and have lost the dielectric reforming I did a few weeks back. They will have to go... time to repack.
Going through the chassis (it is a CTC5 Deluxe) I have found an RCA factory modification which I feel was poorly executed. Mine is a "P" chassis and the later factory runs had the modification to improve grey scale between color (burst on) and black and white (burst off) programming. The plate supply for the first chroma bandpass amplifier was originally attached to the +300 vdc line through a 6.8kohm resistor dropping resistor. The modification moved the supply to the +385vdc line dropped through a 10kohm resistor. The modification meant that the power dissapation for the dropping resistor increased substantially (to 8.5 watts). This left charred insulation and components near the resistor. Because the chroma unit is enclosed, the ventilation is poor which made a bad situation worse. All the wax capacitors showed evidence of melting!
I decided to split the resistance: I installed a terminal strip near the rectifier ventilation and installed a 6.8k 10 watt resistor there. This was in series with a 3.3kohm 5 watt resistor mounted in the chroma chassis exactly where the 10kohm resistor was. The 3.3kohm resistor will dissipate now just over two watts.
Note the photo of the charred remains of the old terminal strip. I had already replaced the charred wiring. The original terminal strip was a miniature unit and I went to the trouble of modifying a larger terminal strip to fit. (I would not expect to make money on a CTC-5 anyhow
).
My set otherwise looks lightly used. I would be curious to hear from others who have the earlier versus the later deluxe chassis and this issue. There must be others with this problem...