February 21, 2021 at 5:48 pm #16269robert clausenForum Participant
I’m attempting to restore a Silvertone 1906 and don’t want to mess up the electrolytic caps. The existing cap, a Mallory. I assume it is taking the place of C-20 and C-9, which were both 8 mfd caps. I include a pic of how this electrolytic was wired. It shows the red wire connected to both ends of the cap. I was hoping someone could tell me why this was done and it’s purpose.
I am going to replace the Mallory cap with two separate 10 mfd caps but want to ensure I have the + and – connections connected properly. Any assistance would be appreciated. My confidence with wiring electrolytics correctly is such that I prefer to get advice from the Forum. My schematic reading training is ongoing.
The last photo is a short red wire soldered to the cathode of tube 84. The other end has come loose. I can’t tell where the loose end used to be attached, and I can’t see anything on the schematic as to where this wire should go. Again…any advice is welcome.
I’m very new to the hobby, so I take no offense to any assistance.
Attachments:February 21, 2021 at 7:36 pm #16273Alistair ThomsonForum Participant
Looking at the schematic, it shows that both +ve terminals of the dual cap are connected together. I’m guessing that this connection is the red wire you see between the ends of the dual cap. So one end of the cap body has two terminals for one 8µF cap and the other cap at the other end. Normally a dual electrolytic will have a common negative can, but this is not the case here. Looks like two completely separate caps in one case, so using two separate replacements is a good idea.
The broken red wire connected to the cathode (K) of the 84 is connected to the common +ve of the two caps, according to the schematic. In the schematic, it meets C9 +ve at the junction with R3.February 22, 2021 at 6:35 pm #16274robert clausenForum Participant
I have only done a couple of radios but I hadn’t come across electrolytics which had common positive connections. So thanks Alistair for explaining it too me and clearing up the issue of the red wire.
My schematic reading is ongoing.
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