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Well, I think that I found the culprit that is causing my hum problem - a leaky capacitor. I pulled my Fisher 800-C out of the cabinet, and here is what I saw:This is what was on the bottom cover immediately below this capacitor:
Does anyone know which capacitor this is? How difficult is it to replace, and where can I find one like it?
Follow Ups:
Click for better resolution photos:
Here is a photo of the underside of the 800-C. If you use the AC power cord as a reference, you should be able to see where the capacitor is.
In the lower left hand corner of the picture of the underside of the chassis, there are two, blue electrolytic caps, the replacement bridge rectifier and supporting carbon film resistors(the tan ones) which is what your tech replaced. What you need to replace are the high voltage electrolytic caps. Those are the ones which will include both 200uf/250WV sections. Again, follow the two red twisted pair leads coming from the power transformer. One red lead will connect to the junction of two diodes. The diodes are new. They have been replaced by your tech. The other red lead will go to the junction of two 200uf/250WV caps. Specifically, the connection is to the body of the paper covered electrolytic cap. It is original. It is worn out. It needs to be replaced. Also, from the body of that worn out cap will be a wire connected to the positive terminal of another electrolytic cap. It will have two sections. One of those sections will also be 200uf/250WV. The other section is probably not worn out. It does not matter. It will have to be replaced anyhow. Finding that second multisection cap will likely be very difficult. You could try at Antique Electronics in Tempe,AZ or at Triode electronics in Chicago. They may be able to help you. If not, you can also use generic high voltage electrolytics under the chassis to do exactly the same job as the original caps. It's not a hard job. Perhaps your tech could do it for you. That's all that's wrong with your receiver. Replace those two caps and you'll be back in business again.
Thanks for the help! Now that I have something to go on, I can try to debug the problem.
There will be two red wires coming from the power transformer secondary winding. One of these red wires will be connected to the junction of two diodes. The other red wire will be connected to the junction of two electrolytic capacitors. Replace the two capacitors with 200uf/250-350WV caps. MAKE SURE that you orient the caps properly. Electrolytic caps have definite positive (+) and negative (-) terminals. Take pictures of the existing wiring before you remove anything.The picture you showed was of a failed cap which has already been made obsolete by your tech. It looks as if he has epoxied over the original bole in the chassis. You can try to dig it out but when you do you will have a big hole in the chassis which is too close to the power transformer to mount a cap which will stay cool.
You might follow the red wires, take a picture of that and post it. Then people can tell you how to proceed from there.
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