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Philco 366 problem with filter choke
#3

I agree with Ron on all points. There is a chance if you remove and open up the shorted choke, you may find the short if it is in the first few layers of the winding. The short was was most likely caused by the failure of one of the ancient electrolytics, which at the time were very expensive, more so than a delicate choke. If you can fix it, and get at least 50-75% of the winding back in service, you will be good to go. I once used the primary winding of an output transformer from a junk portable using a 3V4 or 3S4 which had a really large impedance to substitute for a smoothing choke (do not connect the secondary winding to anything,) and upped the values of the filter capacitors, and the d**n thing worked like a charm. Physically about the same size, and it'd take a real nit picker to find out that is what I did.

Don't try any really large value capacitors as they would burden the rectifier, and possible cause it to fail, or worse yet, cause a problem with the power transformer. Ron's suggestion of a 22 mfd is appropriate for the first part of the pi filter, you could do a 33 or 4o mfd after the 2200 ohm resistor and still be OK.

You can use the tool from the following web site to approximate what will happen. Remember the 80 morphed into a 5Y3, and so on. It's free, and really pretty good.

http://www.duncanamps.com/psud2/index.htm

Best of luck!


Messages In This Thread
Philco 366 problem with filter choke - by Guest - 03-22-2009, 12:32 PM
Re: Philco 366 problem with filter choke - by codefox1 - 03-22-2009, 03:55 PM
Re: Philco 366 problem with filter choke - by Guest - 03-23-2009, 12:34 AM
Re: Philco 366 problem with filter choke - by Guest - 03-28-2009, 01:42 AM



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