Hello everyone
I am from italy and I purchased a Magnavox R3D horn. The coils tests at 705 ohms the input, and 9.5 ohms the battery, and from my scarce information sources they should be the right values.
Anyway the driver appears frozen and no sound from the horn.
I think it is a mechanical trouble probably due to the driver diaphragm
frozen for some reason (rust?).
Before to open the base, in order to avoid some bad move, I need literatures
or drawings from any kind of service manual related to this equipment.
If someone can help me, please let me know.
Obviously I will cover any kind of cost.
Thank you in advance
Regards
Paolo Ghini

Hello Paolo, I'm surprised no one's been able to answer your questions. I don't have one of these Magnavox drivers but I think I know someone who has. If it's what I'm thinking of it's a moving coil driver for a horn with a copper disk diaphram and 6 volt field coil. I'll try and contact the owner and find out some information. He might be away at present, he's elderly and as it's Winter here in Australia he often goes North where it's warm for a couple of Months. I'll let you know what I can find out. I also think I remember an article on the speaker, if I can find it I'll send it to you. Don Black.

: Hello everyone
: I am from italy and I purchased a Magnavox R3D horn. The coils tests at 705 ohms the input, and 9.5 ohms the battery, and from my scarce information sources they should be the right values.
: Anyway the driver appears frozen and no sound from the horn.
: I think it is a mechanical trouble probably due to the driver diaphragm
: frozen for some reason (rust?).
: Before to open the base, in order to avoid some bad move, I need literatures
: or drawings from any kind of service manual related to this equipment.
: If someone can help me, please let me know.
: Obviously I will cover any kind of cost.
: Thank you in advance
: Regards
: Paolo Ghini

Hello Paolo, I've spoken to my friend today with the Magnavox moving coil horn driver that I thing is similar to yours, it's made in England but very similar to the US version. There are 4 screws that hold the front plate on where the horn is attached. If you remove these you should gain access the the diaphram, it's a flat copper disk. The touble might be a frozen voice coil from rust or "gunk", it could also be an open circuit voice coil. The 705 ohms sounds OK for the transformer primary, the secondary is thick wire and is unlikely to be open. You could disconnect on secondary wire so you can check the secondary and voice coil resistance. I've seen the speaker a while ago and from memory it's pretty straight forward. I'm fairly certian it's designed to operate the field coil from a 6 volt (A) battery. Let's know if you need any further help, I can ask questions if you're stuck. Good Luck, Don Black.

: Hello Paolo, I'm surprised no one's been able to answer your questions. I don't have one of these Magnavox drivers but I think I know someone who has. If it's what I'm thinking of it's a moving coil driver for a horn with a copper disk diaphram and 6 volt field coil. I'll try and contact the owner and find out some information. He might be away at present, he's elderly and as it's Winter here in Australia he often goes North where it's warm for a couple of Months. I'll let you know what I can find out. I also think I remember an article on the speaker, if I can find it I'll send it to you. Don Black.

: : Hello everyone
: : I am from italy and I purchased a Magnavox R3D horn. The coils tests at 705 ohms the input, and 9.5 ohms the battery, and from my scarce information sources they should be the right values.
: : Anyway the driver appears frozen and no sound from the horn.
: : I think it is a mechanical trouble probably due to the driver diaphragm
: : frozen for some reason (rust?).
: : Before to open the base, in order to avoid some bad move, I need literatures
: : or drawings from any kind of service manual related to this equipment.
: : If someone can help me, please let me know.
: : Obviously I will cover any kind of cost.
: : Thank you in advance
: : Regards
: : Paolo Ghini

Hello Paolo - Don is correct. that speaker has a 6-volt field coil with must be energized before you will hear any sound from the coice coil. energize the field coil with a 6-volt source and try again before disassembling the speaker. Good luck !