Name That Cap

[Tubejunke]

Still fooling with the Space Command, I found what looks to be a ceramic disc but much larger than the others at near the size of a quarter dollar. The cap is yellow in color with what looks to be a CRL logo and 110-k, and also 4kv markings. I have a close to correct schematic for this set and it lists a 100mfd. Isnt that kind of large for a disc? I guess I tend to think of discs as being very small capacity, the wax paper is usually the second largest, and the largest values are usually wet electrolytic. This cap is in my sound discriminator circuit with a 6bn6 tube. The cap seems to be open. I have seen some low value orange drops that are so high resistance they dont give any reading with an ohm meter, but a 100mfd should give a good kick with an analog and read some high resistance on a digital. I get nothing. So any info on these caps would be great. The 4kv leads me to think 4000 volts but that thing is in a 265v circuit. Maybe this is the cause of the hum in my sound. I have started checking out discs since nothing else worked.

[Chad Hauris]

100 mfd (microfarads) is too large for a ceramic cap...maybe is it 100 mmfd (micromicrofarads, or in newer terms, picofarads....a millionth of a microfarad)

[wa2ise]

That 4KV ceramic cap is the sort normally used in the horizontal deflection circuitry. Doesn't seem likely to be used in the sound detector. As Chad points out, it's likely 100pF and thus would look to be open with your ohm meter. Does it look like original equipment, or a repair part? In either case, it might have been a case of a lack of regular 100pF caps either in production or the shop, and were used to get the TVs shipped or back to the customer. Sure, the 4KV part would be expensive, but holding up production would be more expensive yet.

[Tubejunke]

My "Bad" is what I guess they say nowadays for ignorance or stupidity, so my bad. I failed to take note that the scematic lists this cap as 100mmf instead of the more familliar mfd. I dont understand why they wouldnt stay with one format where capacity is concerned. I dont mean physically but value listing. Wouldnt the 100mmf cap really be a .0001mfd. Am I mistaken in my conversion? The other weird thing is the other low value caps are simply listed as .0047, .0068 ect...without any mmf, mfd. The only designated values are the cans which are listed as mfd, and the strange yellow discs. There are 3 and they all are listed as I mentioned, for instance another is listed as 470mmf. These yellow caps must be special as they are listed differently than any other. Even the other more common reddish brown discs have no special designation. They do not look like replacements during past repair. Thanks guys! At least now I dont think anything is open. I was a little excited thinking that I had found some kind of problem. I am running out of ideas on this one.....