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 Post subject: Resistor Values
PostPosted: Apr Fri 03, 2020 2:34 am 
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Looking over the parts list of a Zenith 5S151 all the resistors are either a few hundred Ohms or many megaohms. I suspect that the higher resistor values are kilohm not megaohm, am I correct? Should the "M"s be "K"s?


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 Post subject: Re: Resistor Values
PostPosted: Apr Fri 03, 2020 2:38 am 
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Yes, M stands for kiloohms. MEG for megaohms.

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 Post subject: Re: Resistor Values
PostPosted: Apr Fri 03, 2020 3:08 am 
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Thanks! I'm also guessing that the capacitors C13 is 0.2 MFD and C15 & C20 are 0.1 MFD?


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 Post subject: Re: Resistor Values
PostPosted: Apr Fri 03, 2020 8:42 am 
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I think you are right, you should be able to confirm that when you get to that part of the curcuit,

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 Post subject: Re: Resistor Values
PostPosted: Apr Fri 03, 2020 11:03 am 
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"M" is the old way of saying "thousand" as in the Roman numeral.
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Thanks! I'm also guessing that the capacitors C13 is 0.2 MFD and C15 & C20 are 0.1 MFD?

C13 is 2uF at 200v, and C15 & C20 are 1uF at 600v and 400v, respectively. Use 630v film caps to replace all of them.
John

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 Post subject: Re: Resistor Values
PostPosted: Apr Fri 03, 2020 12:11 pm 
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The specifications for your Capacitors part numbers can be seen on pdf-page nine and 10 (and elsewhere) in this 1937 Zenith parts catalog.

Examples:
22-250 .05µF (microfarad) 200V paper tubular.
22-384 .0015µF 600V mica.

1937 Zenith parts catalog. (49-pages).
http://www.tuberadios.com/zenith/zenithcomponent.pdf

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A "micro-microfarad" (μμF, and confusingly often mmf or MMF), an obsolete unit sometimes found in older texts, is the equivalent of a picofarad. In texts prior to 1960, and on capacitor packages even much more recently, mf or MFD rather than the modern µF frequently represented microfarads. Similarly, mmf or MMFD represented picofarads.

μF (microfarad)

pF (picofarad)

Random examples...
.002μF (microfarad) equals 2000pF (picofarad)
.00025μF equals 250pF

to convert from μF to pF
Here's a handy capacitor conversion chart.
http://justradios.com/uFnFpF.html

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fyi... for other schematics that you may encounter...

Resistors...
Capital M (the old fashioned notation) on the schematic is the Roman numeral for 1000
Example: 100M equals 100K equals 100,000Ω

Also seen on some older schematics: stylized→ ω represents the lowercase Greek letter omega.

------------


Greg.


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 Post subject: Re: Resistor Values
PostPosted: Apr Fri 03, 2020 7:00 pm 
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Joined: Jun Sat 15, 2019 7:43 pm
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jsweinrich wrote:
Thanks! I'm also guessing that the capacitors C13 is 0.2 MFD and C15 & C20 are 0.1 MFD?

You are correct

DM


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