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philco 90 ecap question - Printable Version

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philco 90 ecap question - bdi1976 - 05-20-2014

Hello forum,
On my last (and first) set, all ecaps connected to ground so the direction of connection was straightforward. On the 90 (single 47) I'm now working on, the ecap (56), which consist of 2 ecaps (10uF and 6uF), connect to the rectifier filaments on one end and the other end connects to the transformer (and BC resistor). I'm a novice - I believe that the B+ line is the rectifier filament line and the B- line is the transformer/BC resistor line. So I assume that the ecaps negative end point toward the B- and positive to the B+ line...is this correct? Secondly, so I understand better, if the original part number 56 had 2 ecaps inside (10uF and 6uF) is it OK to substitute with a single 16uF (630V)? I appreciate any input you guys have-
Also, the schematic is attached - page 4 at the bottom
bdi

RE: philco 90 ecap question - Steve Davis - 05-20-2014

A single capacitor won't work. Number 56, the input capacitor connects positive to the 80 filament and to the input of the filter choke, negative to the HV center tap. Number 57 connects positive to the output of the filter choke and negative to chassis ground.

Steve

RE: philco 90 ecap question - Mondial - 05-20-2014

Cap 56 has only one cap inside. It is either 6 uF for 50-60 cycle models, or 10 uF for 25-40 cycle models, it is not a dual cap. Same for the second filter cap 57.

RE: philco 90 ecap question - bdi1976 - 05-21-2014

wow...I was wrong about everything. So the pos of the 56 to the transformer line, neg to the rectifier filaments. I was confused by the 6uF and 10uF specifications for the same cap since someone replaced the previous 57 cap with a 16uF cap. I have the 50-60 cycle model, so I should be back on track now. Thanks for the clarity guys. Please let me know if my summation of your info is incorrect.

RE: philco 90 ecap question - Ron Ramirez - 05-21-2014

No, no, no...

Look here:

http://www.philcoradio.com/tech/images/90b.jpg

Positive of (56) to the junction of one leg of the 80 filament and the input lead of choke (55).

Negative of (56) to B- which is the high voltage secondary center tap, lead 12, and its junction with the bias or B-C resistor ( 58 ), terminal 1.

Now:

Positive of the output electrolytic (57) to the junction of the output lead of choke (55) and the speaker socket as indicated on the schematic.

Negative of (57) to chassis ground.

If you cannot read schematics or are having difficulty, STOP and learn to read schematics before proceeding. If you do not know what you are doing, you may fry a power transformer or other component, or worse yet, fry yourself...and we do not want that to happen.

http://www.antiqueradio.org/howfix.htm

RE: philco 90 ecap question - bdi1976 - 05-21-2014

Thanks Ron - I believe I am reading them properly, however, the schematic I have (from NostalgiaAir) does not show the polarity of the ecaps like the one you provided. My last reply was accidentally incorrectly stated - my mistake. My original thread correctly stated my intention of matching pos to B+ and neg to B-, which matches your statement. Thanks for sending the schematic. I appreciate your input-

RE: philco 90 ecap question - Ron Ramirez - 05-21-2014

Good. Icon_smile

And please do not misunderstand - I am definitely not trying to talk down to you - I'm only trying to help.