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-   -   Atwater-Kent cap replacement advise needed. (http://www.videokarma.org/showthread.php?t=253275)

HiFiCanada 01-24-2012 03:46 AM

Atwater-Kent cap replacement advise needed.
 
Anyone have information as to get the caps out of the Atwater-Kent model 40 power pack? The caps are in the pack as I understand and how do I get them out and were in the pack are they. I was going to lite the BBQ and start pouring the tar out into a steel bucket to keep for later, when I need to fill the pack again, that is, if I should fill the pack again.
Not to worry, I am a welder fabricator, so I am use to fires.
Any photos would be helpful on how to do this.
I first thought that the caps were in the cans on the radio, but I guess those are not the electrolytic caps for the power supply, that I need to be concerned about.
The radio works, all the tubes light up and I even got a 455kc squeal with my RF generator near the radio, so the transformer is good.

7"estatdef 01-24-2012 01:33 PM

Check the Atwater Kent site there's an article describing how to do it.
Terry

Electronic M 01-24-2012 01:46 PM

455KC? That is an IF frequency! This set is a TRF not a superheterodyne so it should not tune or respond to 455KC. Unlike the superhetrodyne sets that were the norm in the octal tube era; TRF sets do not have an IF system nor a converter/mixer osc system. A TRF basically takes the antenna input, filters one station with a coil and a variable cap, and sends the signal to an amplifier. Which, from there, feeds as many additional stages of identical inductor-capacitor filters and amplifiers as there are tubes between the first tube off the antenna and the detector.

That large can with all the wires going to it, I believe is the power supply, and should not be messed with unless the hum is really bad or one of the supply voltages is significantly off.

teevee 01-25-2012 11:19 AM

Typical problems with these sets are the 2 resistors in the power pack, before tearing needlessly into the power pack, check these. Looking at the set from the front, you should have voltage on the 4 rightmost terminals on the pack. Directly underneath these terminals are the 2 resistors (65K and 12.5K) Also, the audio transformers are noted for opening up. A quick resistance check will prove these out. Lastly, the grid "stopper" resistors (on the back of the tuning caps) corrode. They should be somewhere around 400 Ohms.

vintagecollect 01-25-2012 11:33 PM

Make it easier for future repairs
 
I would strongly suggest just getting rid of that weird black goo. I would be cautious to have good hygeine before and after dealing w/ this. May have pcb or other mystrey chemicals???
I'm sure AK thought it would be in business forever and did this only for people to rely on facory replacement parts.
A cut to size black plastic bottom cover from TAP, w/ holes drilled just big enough for wires to create same effect and easier access for repairs, little black wax melted over plastric.
If you're really bent on reproducing same effect and look, why not make new block out entirely of black wax to cover parts. Repairs could be done by simply putting can in boiling water to melt out parts and wax. Looks the same, just more service friendly.

post pics of set please and parts value info, this sets has always interested me. That cap block keeps most of those sets as display pieces. What year are these? One of my old friends from years ago was big AK collector had one not working for display only.

HiFiCanada 01-26-2012 03:12 AM

Yea, i'll have to do this outside some were, with welding gloves on, I just need to know whats inside and were it is located.
I don't want to move anything in there if I don't need to, except replace the caps.
The caps just got to be replaced, and I am not looking forward to that, but the queston is, how hot do I got to get this tar, so that it can be spooned out, or will it pour out very slowly
The black wax is a good idea
I got this set with the E-3 speaker, that is already restored

http://s1042.photobucket.com/albums/...%2040%20radio/

http://i1042.photobucket.com/albums/...1928HHMeg2.jpg

Reece 01-26-2012 07:21 AM

Most do not replace or reproduce the tar/wax. There is no need for it with modern components. If you hide them inside the box, nobody will ever know and the tar/wax will serve no purpose anyway.

sean 01-26-2012 08:02 AM

I have rebuilt 3 or 4 of those power packs. The first one I did I tried melting the tar out but it made more of a mess. What I found works well is to chip the tar enough to get access to the wires that are imbedded in there. That way you can clip the wires going to the capacitors and install new capacitors under the terminal board. The pack is separated into 3 sections. One contains the power transformer, one the capacitors, and one I believe has a choke and maybe another capacitor. I suggest you read this article on rebuilding these power packs:

http://www.atwaterkent.info/Articles/AKPower.pdf

HiFiCanada 01-27-2012 03:17 AM

Quote:

Originally Posted by sean (Post 3025207)
I have rebuilt 3 or 4 of those power packs. The first one I did I tried melting the tar out but it made more of a mess. What I found works well is to chip the tar enough to get access to the wires that are imbedded in there. That way you can clip the wires going to the capacitors and install new capacitors under the terminal board. The pack is separated into 3 sections. One contains the power transformer, one the capacitors, and one I believe has a choke and maybe another capacitor. I suggest you read this article on rebuilding these power packs:

http://www.atwaterkent.info/Articles/AKPower.pdf

I afraid that once I start to chip away at the tar, I could damage something, since not being familiar with what and were everything exactly is. The article explains good, but I could still break something. Once I am familiar with the pack, the second one would be a good candidate.


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