September 15, 2022 at 5:25 pm #18964Ralph SpracklinCVRS Member
I have not really started on the restoration of this Marconi 221 Radio-Phono. I recently picked this unit up while driving through Nova Scotia. However I have just run into my first problem. This unit has, among others, two old Aerovox Wax Paper capacitors installed in it, which I cannot find on the Schematic. Those two actual capacitors read 10-47 at 300 volts and 10-47 at 400 volts. Normally they should read, I think .47mf, if that is indeed their value. But the letters mf does not appear on the said capacitors either. And why would the 10 numerals appear.
All other capacitors are same design Arovox capacitors using properly capacitor values. I also am able to account for all other capacitors used in the building of this unit. My first thought was that these were two .47 mf capacitors, but why would they not be on the schematic. The two said capacitors mentioned seem to be original to the unit, both in style and soldering workmanship. Has anyone seen any Aerovox Capacitors marked as such, regarding value in micro fareds????????????
RalphSeptember 15, 2022 at 6:20 pm #18965Les DicksonCVRS Member
Ralph, can you add some photos?September 16, 2022 at 11:44 am #18966John GreenlandCVRS Member
It might also help if you traced inside the radio where these caps are connected. A tube base pin would be a good start.
I am pretty certain that there are a few fellows in this group that will be able to tell you the why and wherefore of these 2 caps.
Regards and good luck with the restoration.September 17, 2022 at 1:38 pm #18969Ralph SpracklinCVRS Member
I have solved the mystery of those two elusive capacitors. I thought I had traced out everything including three .05 Mf Caps. on the schematic. I stumbled upon the third whichwas a like cap and it was marked as .05 Mf, and it was identical to the two problem caps. Actually, as to the 10-47 markings on those caps, I think these markings represent the date of manufacturer by Aerovox. In this case October 1947. Anyway I should have figured it was something simple. I am making progress on this unit. The sound and volume for the Phono is now working OK. This unit was manufactured in 1950. Maybe the problem with the Radio is one of the up-front tubes or something in the RF/IF section. Surprisingly the electrolytics seem OK, no hum whatsoever, but they will have to go, along with a couple of questionable resistors and the three ,05 caps. Of course there is still the cabinet to refinish, and the Record Changer too, which needs a overhaul.
Thanks for your input.
- This reply was modified 2 weeks, 5 days ago by Ralph Spracklin.
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