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hey guys, ran aground on something. Going through an AK model 708 and doing parts vs schematic checks and finding some wax/paper caps that have 3 digit markings on them.
One has 101 on it and another has 409 on it.
I would think that that's .0001uF and 0.0004uF respectfully.
Doesn't match the schematic values at all. ( I realize that there have probably been several production changes so there could be differences).
I plan on replacing these caps using the printed values on them and probably going to restuff the old ones if I can. A lot of work but I want this thing to be authentic as possible.
Done some internet research on this but not finding what I think is the right information.
Also, Haven't worked on any thing this old as this radio so learning about the old way of doing things.
Thanks.
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I restored 808A which is more or less the same as 708, only console, many years ago. Maybe 8 or 9.
I do not remember if I tried to read values, but I think I went by the drawing and the sch so I did not question values.
I would advise going with the sch values if you are sure the cap in question is accurately located on the sch.
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The 3 digit code on the A-K caps is an in house code. That code does not follow the current capacitor coding schemes nor is representative of the caps value.
Look at the circuit location and the schematic to determine the correct value.
Chas
Pliny the younger
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Thought the values remain constant. So once you figure out that a "123" is .01 @ 200V then so is the next one.
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My experience on A-K house marked caps is that the same "code" is consistent with that radio model. Chances are that same code is used in similar models. too. However, I have found that is not true of A-K resistor color codes, for example, a white (all white dog bone resistor) FWIR, can appear in two places in the same radio at different values.
That said, when restoring, care has to be taken not to be deceived in both capacitor codes as well as resistor color coding schemes on sets built before RMA became standard practice.
I cannot vouch to where I read this, long before the WEB that Philco used RMA codes but values chosen of such the colors would stand out in the factory lighting scheme.
Chas
Pliny the younger
“nihil novum nihil varium nihil quod non semel spectasse sufficiat”
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Some months ago I was fortunate enough to come across an original Atwater Kent ring binder of their service information from their beginning through 1933. I have looked through it to see if I could find any direct information to answer your questions. What I found is that in this early period they went by their own part number and color code system, and that it varied between models over the period. I STRONGLY suggest you follow the values on the schematic for the parts. The numbers on the condensers are NOT related to their value. The same goes for the colors on the resistors. Here is the schematic for the model 808A, which, from what I can find, is the same as your 708. I hope it can be of some use to you.
[Image:
https://64.media.tumblr.com/fec5c52c4f2c...442e2b.jpg]
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A little further research. The 708 is the table radio, the 808 is the floor model. The circuitry and chassis are the same, not sure if the speaker diameter is the same.
