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Zenith 7H920 Restoration
#32

So, after quite a bit of troubleshooting and attempted IF signal through, which came weak and with lots of hum, I eventually decided to re-take voltages and realized the 2nd IF Cathode is high, 38V.
So, what happened was, during the recap I severed 100 Ohm Cathode feedback resistor, leaving just the cap.
I re-instated the resistor, and the radio immediately started playing, and it does play great on both AM and FM. Big booming sound with the chassis outside the cabinet (I doubt the backelute cabinet will add much).

I will still go through the IF and the bands alignment, as I disturbed the IF trying to peak.

I will shoot a little video later and place it with my Youtube channel.



Also, I realized that the Selenium Rectifier was giving me lower than required voltage: Where I needed 130V on the first rectifier cap, I was getting below 100V, if not below 90V.
I put a 1N4007 diode and added an 82 Ohm resistor.
From the measurements the resistor drops 6V, and so the dissipatrion is 0.45W or so, but the reesistor (a ceramic 5W) gets uncomfortably hot, can't be touched, so I am not sure what to do: the voltage is a bit higher than needed at 117VAC (and it is 127VAC at my place) but the larger the resistor the hotter it will get.
I could reinstate the SR and the 22 Ohm resistor that was there, I am sure it will work, but then the voltage will be too low.

People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.


Messages In This Thread
Zenith 7H920 Restoration - by morzh - 12-17-2025, 10:03 PM
RE: Zenith 7H920 Restoration - by MrFixr55 - 12-17-2025, 11:14 PM
RE: Zenith 7H920 Restoration - by radiorich - 12-18-2025, 01:01 AM
RE: Zenith 7H920 Restoration - by Arran - 12-18-2025, 07:12 AM
462ron - by 462ron - 12-18-2025, 08:27 AM
RE: Zenith 7H920 Restoration - by RodB - 12-18-2025, 12:02 PM
RE: Zenith 7H920 Restoration - by morzh - 12-18-2025, 12:31 PM
RE: Zenith 7H920 Restoration - by rfeenstra - 12-19-2025, 12:54 AM
RE: Zenith 7H920 Restoration - by MrFixr55 - 12-19-2025, 03:02 PM
RE: Zenith 7H920 Restoration - by Arran - 12-19-2025, 03:37 PM
RE: Zenith 7H920 Restoration - by Arran - 12-19-2025, 07:51 PM
RE: Zenith 7H920 Restoration - by David - 12-20-2025, 09:43 AM
RE: Zenith 7H920 Restoration - by morzh - 12-20-2025, 01:30 PM
RE: Zenith 7H920 Restoration - by morzh - 12-20-2025, 08:26 PM
RE: Zenith 7H920 Restoration - by David - 12-20-2025, 08:51 PM
RE: Zenith 7H920 Restoration - by morzh - 12-20-2025, 10:50 PM
RE: Zenith 7H920 Restoration - by MrFixr55 - 12-21-2025, 12:13 AM
RE: Zenith 7H920 Restoration - by morzh - 12-21-2025, 11:01 AM
RE: Zenith 7H920 Restoration - by morzh - 12-21-2025, 10:31 PM
RE: Zenith 7H920 Restoration - by morzh - 12-22-2025, 09:33 PM
RE: Zenith 7H920 Restoration - by Paul Philco322 - 12-22-2025, 09:42 PM
RE: Zenith 7H920 Restoration - by morzh - 12-22-2025, 10:51 PM
RE: Zenith 7H920 Restoration - by Arran - 12-23-2025, 04:26 AM
RE: Zenith 7H920 Restoration - by MrFixr55 - 12-23-2025, 08:35 AM
RE: Zenith 7H920 Restoration - by morzh - 12-23-2025, 02:25 PM
RE: Zenith 7H920 Restoration - by David - 12-23-2025, 07:14 PM
RE: Zenith 7H920 Restoration - by MrFixr55 - 12-23-2025, 08:30 PM
RE: Zenith 7H920 Restoration - by morzh - 12-23-2025, 09:04 PM
RE: Zenith 7H920 Restoration - by morzh - 12-24-2025, 08:18 PM
RE: Zenith 7H920 Restoration - by morzh - 12-25-2025, 11:43 AM
RE: Zenith 7H920 Restoration - by morzh - 12-26-2025, 09:54 AM
RE: Zenith 7H920 Restoration - by morzh - 12-30-2025, 06:07 PM
RE: Zenith 7H920 Restoration - by Arran - 12-30-2025, 07:28 PM
RE: Zenith 7H920 Restoration - by morzh - 12-30-2025, 07:32 PM
RE: Zenith 7H920 Restoration - by Arran - 12-30-2025, 10:49 PM
RE: Zenith 7H920 Restoration - by RodB - 12-31-2025, 11:55 AM
RE: Zenith 7H920 Restoration - by Vlad95 - 12-31-2025, 01:43 PM
RE: Zenith 7H920 Restoration - by RodB - 12-31-2025, 04:30 PM
RE: Zenith 7H920 Restoration - by David - 12-31-2025, 07:03 PM
RE: Zenith 7H920 Restoration - by morzh - 12-31-2025, 09:12 PM
RE: Zenith 7H920 Restoration - by morzh - 12-31-2025, 09:21 PM
RE: Zenith 7H920 Restoration - by Vlad95 - 12-31-2025, 09:44 PM
RE: Zenith 7H920 Restoration - by morzh - 12-31-2025, 10:48 PM
RE: Zenith 7H920 Restoration - by Vlad95 - 12-31-2025, 11:26 PM
RE: Zenith 7H920 Restoration - by morzh - 12-31-2025, 11:48 PM
RE: Zenith 7H920 Restoration - by Vlad95 - 01-01-2026, 12:03 AM
462ron - by 462ron - 01-01-2026, 09:16 AM
RE: Zenith 7H920 Restoration - by RodB - 01-01-2026, 11:01 AM
RE: Zenith 7H920 Restoration - by RodB - 01-01-2026, 12:10 PM
RE: Zenith 7H920 Restoration - by morzh - 01-01-2026, 12:28 PM
RE: Zenith 7H920 Restoration - by Vlad95 - 01-01-2026, 01:37 PM
RE: Zenith 7H920 Restoration - by RadioSvit - 01-01-2026, 03:57 PM
RE: Zenith 7H920 Restoration - by RodB - 01-01-2026, 03:57 PM
RE: Zenith 7H920 Restoration - by Vlad95 - 01-01-2026, 04:10 PM
RE: Zenith 7H920 Restoration - by morzh - 01-01-2026, 05:52 PM
RE: Zenith 7H920 Restoration - by morzh - 01-01-2026, 05:54 PM
RE: Zenith 7H920 Restoration - by morzh - 01-01-2026, 05:57 PM
RE: Zenith 7H920 Restoration - by KCMike - 01-02-2026, 02:55 PM
RE: Zenith 7H920 Restoration - by morzh - 01-02-2026, 07:08 PM
RE: Zenith 7H920 Restoration - by morzh - 01-02-2026, 10:44 PM
RE: Zenith 7H920 Restoration - by radiorich - 01-03-2026, 01:07 AM
RE: Zenith 7H920 Restoration - by morzh - 01-03-2026, 11:47 AM
RE: Zenith 7H920 Restoration - by morzh - 01-03-2026, 04:01 PM
RE: Zenith 7H920 Restoration - by morzh - 01-03-2026, 05:20 PM
RE: Zenith 7H920 Restoration - by Vlad95 - 01-03-2026, 05:26 PM
RE: Zenith 7H920 Restoration - by morzh - 01-03-2026, 05:44 PM
RE: Zenith 7H920 Restoration - by radiorich - 01-03-2026, 10:53 PM
RE: Zenith 7H920 Restoration - by morzh - 01-03-2026, 11:49 PM
RE: Zenith 7H920 Restoration - by morzh - 01-03-2026, 11:53 PM
RE: Zenith 7H920 Restoration - by morzh - 01-04-2026, 07:29 PM
RE: Zenith 7H920 Restoration - by MrFixr55 - 01-04-2026, 09:56 PM
RE: Zenith 7H920 Restoration - by morzh - 01-04-2026, 10:04 PM
RE: Zenith 7H920 Restoration - by radiorich - 01-04-2026, 10:09 PM
RE: Zenith 7H920 Restoration - by morzh - 01-04-2026, 10:17 PM
RE: Zenith 7H920 Restoration - by radiorich - 01-04-2026, 11:34 PM
RE: Zenith 7H920 Restoration - by MrFixr55 - 01-05-2026, 06:31 AM
RE: Zenith 7H920 Restoration - by radiorich - 01-05-2026, 09:13 AM
RE: Zenith 7H920 Restoration - by morzh - 01-05-2026, 10:15 AM
RE: Zenith 7H920 Restoration - by morzh - 01-05-2026, 01:14 PM
RE: Zenith 7H920 Restoration - by morzh - 01-05-2026, 04:16 PM
RE: Zenith 7H920 Restoration - by morzh - 01-11-2026, 07:50 PM
RE: Zenith 7H920 Restoration - by MrFixr55 - 01-11-2026, 10:12 PM
RE: Zenith 7H920 Restoration - by morzh - 01-11-2026, 10:35 PM
RE: Zenith 7H920 Restoration - by DaleHCook - 01-12-2026, 10:31 AM
RE: Zenith 7H920 Restoration - by morzh - 01-12-2026, 02:30 PM
RE: Zenith 7H920 Restoration - by DaleHCook - 01-12-2026, 03:23 PM
RE: Zenith 7H920 Restoration - by David - 01-15-2026, 05:30 PM
RE: Zenith 7H920 Restoration - by morzh - 01-15-2026, 05:44 PM



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