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 Post subject: AK 40 Tar Cans
PostPosted: Feb Fri 20, 2004 5:35 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 48
Location: Midwest
Well, I decided to wait on the tar dumping for this evening. But I do have a few more questions:<P>1. Why are these components set in tar in the first place?...is it a good insulator?<P>2. Once I replace the components in the various cans, do I dump the heated tar back in? (on the brand new component?!)<P>3. There is some sort of tape wrapped packet next to the volume control...what exactly is that thing? (and what do I replace it with?)<P>Thanks in advance for the info. I'm not trying to be cynical or anything; these things have just puzzled me from the beginning.<P>Timnic<P>P.S. the rewiring is going quite well. My soldering skills have improved drastically and I believe the tough part is done (soldering to the R.F. Transformers without disturbing the coils!)<P>------------------<BR>Married to a card holding member of WAPSBINO; Wives Against Power Supply Baking In New Oven!


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 Post subject: AK 40 Tar Cans
PostPosted: Feb Fri 20, 2004 6:40 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 30698
Location: Pocasset, Cape Cod, MA
Potting in tar or wax was pretty common in those days. It kept moisture out (for a while), looked good from the outside, and was relatively cheap (residue from oil refining).<P>I wouldn't recommend re-using the tar/wax. There's no need, it adds to the difficulty, and the vapors contain chemicals you shouldn't really be breathing.<BR>------------------<BR>


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 Post subject: AK 40 Tar Cans
PostPosted: Feb Fri 20, 2004 7:41 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 37195
Location: Livermore, CA
Hi Timnic<P> Answer to #3 - There is a capacitor wired in series with your speaker terminal. This capacitor may have been replaced and taped by your volume control. <P> Agree with Alan, no need to reuse the tar. They thought it kept moisture out but really didn't. You will find plenty of rust under the tar. Another reason for tar, AK wanted to sell replacement parts. <P>------------------<BR>Norm


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 Post subject: AK 40 Tar Cans
PostPosted: Feb Fri 20, 2004 7:42 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3667
Location: Circleville, OH, USA
That "tape wrapped thing" sounds like a replacement for the speaker coupling cap. The original was in a flat metal box mounted on the front of the subpanel. Be sure to replace it. It keeps high voltage off the speaker. I think the original value was 0.25µF, but I use 0.47/400V when replacing in the original box.<P>------------------<BR>


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 Post subject: AK 40 Tar Cans
PostPosted: Feb Fri 20, 2004 3:39 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 48
Location: Midwest
Thanks Gentlemen!<P>------------------<BR>Married to a card holding member of WAPSBINO; Wives Against Power Supply Baking In New Ovens!


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