UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Aga Baltic AH37. Need help identifying old capacitor from 1930s radio

Mrgroovy · 18th Oct 2018, 7:56 am

Ok, I'm having a hard time getting any readings from the mains transformer. Don't know if I'm doing it all wrong or if there might in fact be something wrong with it. I found that there is continuity between both wires going into the primary.

There is also continuity between both pins on the power cord. It is a brand new cord and I'm 100% sure the cord is ok. Furthermore, I've traced the continuity and it goes all the way into the primary. Based on my very limited knowledge, I would automatically assume there is a short, but then I am surprised that it wouldn't blow a mains fuse when powering it up and all the tubes are lighting up so there is definitely voltage on the secondary. Which means, it can't be a short, or can it? Have not tried measuring the HT voltage. However, I can't seem to get any ohm readings. When powering up the radio (not for long of course since there is a bad hum from the power transformer), I get some radio transmitting noise. If there was a short on the HT but not on the windings to the filament, if that is even possible, that shouldn't result in any noise or sound at all, right? Just thinking out loud...

As for the chokes the readings are:

Choke in the middle: 5.29K
Choke at the rear: 4.73K
Choke at the side: 1,58K

OT: 1.1K

Speaker field coil: 1.3M This sounds very high compared to the other coils, but that's what it says. Don't know it this is within normal readings for a speaker field coil.

Back to the PT: There is no physical connection between the primary and the secondary, right? So, I really shouldn't get any impedance readings (other than infinite) when it is not powered? If I've understood the science of power transformer it is the magnetic field created between the primary and the secondary when the primary is connected to the mains that in turn makes a "connection" between the primary and the secondary. So when I try to measure between the windings on the primary and the windings on the secondary with no voltage connected I shouldn't get any readings? Please correct me if I'm wrong.

18th Oct 2018, 7:56 am	#123
Mrgroovy Retired Dormant Member Join Date: Oct 2018 Location: Oslo, Norway Posts: 61	Re: Aga Baltic AH37. Need help identifying old capacitor from 1930s radio Ok, I'm having a hard time getting any readings from the mains transformer. Don't know if I'm doing it all wrong or if there might in fact be something wrong with it. I found that there is continuity between both wires going into the primary. There is also continuity between both pins on the power cord. It is a brand new cord and I'm 100% sure the cord is ok. Furthermore, I've traced the continuity and it goes all the way into the primary. Based on my very limited knowledge, I would automatically assume there is a short, but then I am surprised that it wouldn't blow a mains fuse when powering it up and all the tubes are lighting up so there is definitely voltage on the secondary. Which means, it can't be a short, or can it? Have not tried measuring the HT voltage. However, I can't seem to get any ohm readings. When powering up the radio (not for long of course since there is a bad hum from the power transformer), I get some radio transmitting noise. If there was a short on the HT but not on the windings to the filament, if that is even possible, that shouldn't result in any noise or sound at all, right? Just thinking out loud... As for the chokes the readings are: Choke in the middle: 5.29K Choke at the rear: 4.73K Choke at the side: 1,58K OT: 1.1K Speaker field coil: 1.3M This sounds very high compared to the other coils, but that's what it says. Don't know it this is within normal readings for a speaker field coil. Back to the PT: There is no physical connection between the primary and the secondary, right? So, I really shouldn't get any impedance readings (other than infinite) when it is not powered? If I've understood the science of power transformer it is the magnetic field created between the primary and the secondary when the primary is connected to the mains that in turn makes a "connection" between the primary and the secondary. So when I try to measure between the windings on the primary and the windings on the secondary with no voltage connected I shouldn't get any readings? Please correct me if I'm wrong.