old-tank Posted March 11, 2017 Share Posted March 11, 2017 2 hours ago, Beemon said: rewind the magnet All of mine have a permanent magnet with associated voice coil windings. I have seen radios that had an electomagnet powered by B+ voltage. Link to comment Share on other sites More sharing options...
JohnD1956 Posted March 12, 2017 Share Posted March 12, 2017 (edited) 1 hour ago, old-tank said: radios that had an electomagnet powered by B+ voltage. What is B+ voltage? Edit: Cancel my request. I looked it up on Google. Unless the internet is wrong, it is the voltage right at the positive battery terminal. Edited March 12, 2017 by JohnD1956 (see edit history) Link to comment Share on other sites More sharing options...
Beemon Posted March 12, 2017 Author Share Posted March 12, 2017 (edited) A voltage is the input DC voltage to the vibrator. B+ voltage is the voltage that is rectified to DC output at the 0Z4 tube. So 12VDC goes into the vibrator, the vibrator turns it into 12VAC, the transformer steps it up to somewhere around 300VAC and the 0Z4 rectifies the voltage to 300VDC. Edited March 12, 2017 by Beemon (see edit history) 1 Link to comment Share on other sites More sharing options...
JohnD1956 Posted March 12, 2017 Share Posted March 12, 2017 (edited) 5 minutes ago, Beemon said: A voltage is the input DC voltage to the vibrator. B+ voltage is the voltage that is rectified to DC output at the 0Z4 tube. So 12VDC goes into the vibrator, the vibrator turns it into 12VAC, the transformer steps it up to somewhere around 300VAC and the 0Z4 rectifies the voltage to 300VDC. Holy Crap! Edited March 12, 2017 by JohnD1956 (see edit history) 1 Link to comment Share on other sites More sharing options...
SpecialEducation Posted March 12, 2017 Share Posted March 12, 2017 i thought the Sonomatic ran closer to 225-250v. seems to me some of the tube plates dont like more than 275v... Link to comment Share on other sites More sharing options...
Beemon Posted March 12, 2017 Author Share Posted March 12, 2017 Oh, I couldn't remember the actual reading, though in my notes now that I'm looking, it says the 0Z4 output is 240VDC. John, vintage radios are very dangerous, do not stick your hand inside a running radio lol. Link to comment Share on other sites More sharing options...
old-tank Posted March 12, 2017 Share Posted March 12, 2017 15 minutes ago, SpecialEducation said: i thought the Sonomatic ran closer to 225-250v. seems to me some of the tube plates dont like more than 275v... ...and I thought it was closer to 100 volts. Somebody needs to measure.;) Link to comment Share on other sites More sharing options...
Joseph P. Indusi Posted March 12, 2017 Share Posted March 12, 2017 (edited) The electromagnet windings on the speakers in old radios served two purposes. The first was to create the magnetic field for the voice coil to operate in and the second was to act as a choke for the B+ voltage filter. Usually there was one electrolytic capacitor before the coil and one after, this arrangement called a Pi filter, gave a relatively smooth DC voltage with little ripple. Joe Edited March 12, 2017 by Joseph P. Indusi mispelling (see edit history) Link to comment Share on other sites More sharing options...
Beemon Posted March 12, 2017 Author Share Posted March 12, 2017 1 hour ago, old-tank said: ...and I thought it was closer to 100 volts. Somebody needs to measure.;) My mother teased the idea of FM and Bluetooth chips for the radio as a graduation gift. If the notion is genuine, I will definitely take a reading at the 0Z4 pins. Link to comment Share on other sites More sharing options...
SpecialEducation Posted March 12, 2017 Share Posted March 12, 2017 Plate voltage on a 12V6GT is normally 250-285 in a push-pull installation. 12BA6, 12BF6, and 12BE6 all look like they are happy down to 100v, but are fine up to 300. I don't remember for sure what I used to get in mine, but 230-240 sounds about right. By the way, if you haven't seen it, here's a neat little pub with some troubleshooting tips... 1 Link to comment Share on other sites More sharing options...
Beemon Posted March 13, 2017 Author Share Posted March 13, 2017 (edited) Here's my rear speaker: The recone kit would work for the speaker cone, but the spider on the original is too small. So I'm back to hunting for a set that will fit. By the way, the Kenwood speaker will not fit the rear shelf because it has a bar through the center of the hole. I found this site that sells custom made speakers to fit OEM applications. The price isn't right for me right now, so I'll keep searching, but might be interesting for others here. Edited March 13, 2017 by Beemon (see edit history) 1 Link to comment Share on other sites More sharing options...
SpecialEducation Posted March 19, 2017 Share Posted March 19, 2017 our FM/mp3 module... 1 Link to comment Share on other sites More sharing options...
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