03-20-2025, 12:59 PM
Edited 03/22/2024 to add info.
For these Zenith AM/FM sets that use selenium rectifiers I have merely swapped in a 1N4007. I upped the filter cap working V to 160 or 200. I have not found an issue. I think that the chassis is hot because it is an AM-FM radio and using caps to make it a "warm" chassis may greatly affect FM performance. I have 4 of these Zenith sets, the H725, the 7H820, and 2 from the early 1960s. All of these sets have interlocks. The newer sets have no exposed screws, and I think that the knobs are captive by their clips and very difficult to completely pull off (tools required) I also have an RCA 8X71. All of these are hot chassis sets. IMHO, it is best to move the power switch to the hot side, add a polarized plug and use screw covers on any exposed screws on the older units.
Someone made mention of the lack of 3 pin grounded outlets on older houses. All US wiring has the "neutral" at ground potential. On all but the oldest outlets (Pre WWII), even ones without grounds, the holes are not equal in size. The longer slot is neutral (or is supposed to be).
Yes, some bad things are done by previous owners of houses. My house was built in 1954 with the original "Romex" brand NM cable with only 2 conductors, no ground. Most of the outlets were 3 prong. New 2 prong outlets are available at the big box stores and electric supply houses. When I changed my service from 60A to 200A (I did this myself and passed inspections from both the electric company and the inspection service directed to me by the town), I replaced all outlets on the original circuits to 2 prong outlets (no ground) with the larger prong being neutral, and replaced all metal switch and outlet plates with plastic ones, in order to pass Underwriter's inspection I had added new circuits for the kitchen, refrigerator, office, TV and room AC units, as there was only 2 lighting circuits and one appliance circuit which supplied kitchen outlets, refrigerator and washer. I may have overwired a little, but I would rather be overwired than underwired. Now have separate circuits for Refrig, Washer, total of 3 Kitchen Counter circuits (One outside outlet shares a kitchen circuit), Utilty circuit in basement separate from the washer. All new living space circuits for general use are AFCI protected, original circuits are GFCI protected. Dryer and range circuits are 4 wire 120 / 240V with seperate neutral and ground. Inpection agent was very happy.
In addition to incorrect polarity, one of the more dangerous things that some that think that they know do is to tie the neutral to the ground pin on these 2 conductor, no ground wire type circuits. If the neutral circuit breaks, the ground now gets hot. (Splices do go bad.) this is the switched neutral on a hot chassis writ large!
For these Zenith AM/FM sets that use selenium rectifiers I have merely swapped in a 1N4007. I upped the filter cap working V to 160 or 200. I have not found an issue. I think that the chassis is hot because it is an AM-FM radio and using caps to make it a "warm" chassis may greatly affect FM performance. I have 4 of these Zenith sets, the H725, the 7H820, and 2 from the early 1960s. All of these sets have interlocks. The newer sets have no exposed screws, and I think that the knobs are captive by their clips and very difficult to completely pull off (tools required) I also have an RCA 8X71. All of these are hot chassis sets. IMHO, it is best to move the power switch to the hot side, add a polarized plug and use screw covers on any exposed screws on the older units.
Someone made mention of the lack of 3 pin grounded outlets on older houses. All US wiring has the "neutral" at ground potential. On all but the oldest outlets (Pre WWII), even ones without grounds, the holes are not equal in size. The longer slot is neutral (or is supposed to be).
Yes, some bad things are done by previous owners of houses. My house was built in 1954 with the original "Romex" brand NM cable with only 2 conductors, no ground. Most of the outlets were 3 prong. New 2 prong outlets are available at the big box stores and electric supply houses. When I changed my service from 60A to 200A (I did this myself and passed inspections from both the electric company and the inspection service directed to me by the town), I replaced all outlets on the original circuits to 2 prong outlets (no ground) with the larger prong being neutral, and replaced all metal switch and outlet plates with plastic ones, in order to pass Underwriter's inspection I had added new circuits for the kitchen, refrigerator, office, TV and room AC units, as there was only 2 lighting circuits and one appliance circuit which supplied kitchen outlets, refrigerator and washer. I may have overwired a little, but I would rather be overwired than underwired. Now have separate circuits for Refrig, Washer, total of 3 Kitchen Counter circuits (One outside outlet shares a kitchen circuit), Utilty circuit in basement separate from the washer. All new living space circuits for general use are AFCI protected, original circuits are GFCI protected. Dryer and range circuits are 4 wire 120 / 240V with seperate neutral and ground. Inpection agent was very happy.
In addition to incorrect polarity, one of the more dangerous things that some that think that they know do is to tie the neutral to the ground pin on these 2 conductor, no ground wire type circuits. If the neutral circuit breaks, the ground now gets hot. (Splices do go bad.) this is the switched neutral on a hot chassis writ large!
"Do Justly, love Mercy and walk humbly with your God"- Micah 6:8
"Let us begin to do good"- St. Francis
Best Regards,
MrFixr55
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