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Philco model 70 rebuild - by Tim P.
#17

Tim

Could you post a pic of what you have so far with your lytics?

The further action depends on where you cut and what cap it is.
If it is what I had in 90 (in 70 I had replacements and they are different, they are aluminum Cornell Dubilier and yours are the copper tube types), you need to clean the tube inside from oxidation if it is there (mine was full of blue crystals - soaking in vinegar worked well).

I cut them right along the groove at the base, at the upper border of the groove (again look in my 90 topic).
Then when all is ready I simply applied a small bead of JB weld close to the rim of the tube and then inserted the base in it.
Make sure the base will fit inside first, if it does not, use something to make it fit (usually it does, simple smoothing/deburring the edge of the cut will just do the trick).

It will not snap as the epoxy remains somewhat flexible (but not too much). However do not screw or unscrew them grasping the tube after that, this will twist it off of the base if the effort is too large (and it might be). And the length of the groove is about 3-4 mm so it will go inside the tube for good enough length to hold well when glued. It will stand up to bumps and knocks, just like I said - do not use it to twist the cap off.

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As for the resistors, I made it a rule for all high-ohms to be 1W rated so then I do not have to ask the question.

You could simply look at the dropout:
say 270V is B+ and then the plate voltage chart says 80V (which is not always true - remember, they used low-impedance meters to measure so in reality the dropout is way less but to be conservative this is good).
Your dropout is thus 190V, and if you have 100K resistor your real dissipated power will be 0.36W (and this is the worst unreal case) so if you use 1W rated you are just fine.


Messages In This Thread
Philco model 70 rebuild - by Tim P. - by TV MAN - 01-29-2014, 10:46 AM
RE: Philco model 70 rebuild - by Tim P. - by morzh - 02-11-2014, 11:37 AM



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