[MrFixr55]

Hi Keefer,

One other thing:

Does this radio have a 0Z4 rectifier or a rectifier with a filament / cathode? If it has a 0Z4, consider replacing it with a 6X5. The 6X5 was designed with car radios in mind, although Philco and Zenith used it quite often for home radios. Check to see of the rectifier socket is wired for it. The pinouts are supposed to be the same, except that the 0Z4 does not use pins 2 and 7 because, being a gas discharge rectifier, it does not have a filament / heater. Some radios are wired to use either tube. Adding the filament wiring will allow either tube. Having the wiring will not affect the use of a 0Z4 tube if desired.

Another possible alternative is to replace the 0Z4 with 3A 1000PRV diodes. It may be prudent to put resistors in the anode leads between the transformer and the diodes (maybe 1K Ohm, 2W. However, the voltage out of the solid state rectifier will be higher than with either tube. Consider filter caps that are 400 or 450 WV.

The issue with the 0Z4 is the voltage / current required to "start" it (for the gas to ionize). I have heard the frequency of the solid state vibrator may be lower than that of a mechanical vibrator. Maybe a lower frequency is preventing the triggering of the tube. Dunno why leaning it on the side will cause the 0Z4 to fire. If you measure "Plate to Plate" AC voltage at the rectifier when the radio is not playing, is it the same or higher as the voltage when the radio is not playing?

Does the manufacturer of the solid state vibrator instruct you to remove the buffer cap? If not, it may be a good idea to have that in place. The vibrator (either mechanical or solid state) does not exactly produce a sine wave; it is more like a square wave, and I wonder if more like car ignition.

[Keefer]

My wife surprised me with aurora design vbx1 vibrator.I want to hard wire to bottom of old vibrator pins but not sure which wires to hard wire it to.I see 2 black and two whitewires coming from transformer.Not exactly sure which wire is what.

[fenbach]

keefer,
attach the contacts labeled TA and TB on the board to the 2 smaller pins of the vibrator base. then connect the contact labeled GND on the board to the big "upper right" pin in my earlier diagram. the one connected to the + side of the battery [= GND]. if you look under the radio, you'll see that the 2 smaller pin sockets are wired to the transformer and the big "upper right" socket is connected to ground. the big upper left socket is connected to 6 volts negative. the aurora vibrator doesn't use it.
did you ever find a loose connection or a short??

[Keefer]

Not yet still looking.

[Keefer]

Thanks again Fenbach.

[Keefer]

So upper right as in pin one?Pin four is also transformer but not used?Sorry I am trying to learn this stuff.

[Keefer]

   

[fenbach]

hi keefer,
i still have a lot to learn myself. in particular how the pins are numbered.
the pin at 12:00 in your picture is the grounded pin. notice the metal strap connected to a rivet. 3:00 and 6:00 are the ones you connect to contacts TA and TB. the 2 tan wires in the picture connect those pins to the transformer. the pin at 9:00 is 6 volts negative, which is not needed for the aurora design vibrator. on the schematic, the 9:00 pin connects to a coil [no.57], a 0.5uf cap [no.58] and the heater of the rectifier tube [the 84] but not to a transformer.
i like to solder the aurora circuit board to a 4-pin vibrator base [with short wires]. that way, you can plug it in or remove it from the radio easily.
i'm curious to learn if the radio works on its side with the aurora vibrator.
bob

[Keefer]

Again Thank You.I was thinking same thing you just told about the pin setup for the aurora design.I will try to put this together in next day or two.I guess we are all still learning things.That is good.Thanks

[Keefer]

Still playing with radio and was wondering why when I touch the controls with screwdriver it changes the way radio sounds.Also may have fried my aurora design vibrator lol.Also I notice the power wire has metal type covering.Is it supposed to be soldered to a capacitor?Also still have hum after changing filter cap.About to put it aside for awhile lol.

[fenbach]

well, keefer,
let's hope someone else can explain why touching the controls with a screwdriver changes the sound. at least, touching the volume control. the tone control connects the plate of the output tube to ground when set for bass. i can imagine your screwdriver changes the capacitance when touching the tone control. that said, these car radios are pretty "touchy" in my experience.
you must be kidding about frying the aurora vibrator. unless you mean literally, like setting it on a hot soldering iron.
i have to think the metal covering [a mesh?] on the power wire is just a shield. a coax cable, in effect. connect both ends of the shield to ground. all the sparking in the ignition system in old cars created considerable interference.
you mentioned changing the filter cap. you do mean caps? no. 64. make sure you also replaced all the caps larger than 0.01 uf that are connected to ground. the tiny bakelite ones typically don't go bad.
are you up to aligning the radio? adjusting the various padders, that is. those adjustments will likely affect the hum. i've also found that flourescent and LED lights will introduce interference. even an AC powered power supply. not a battery, tho.

[MrFixr55]

Hi Keefer,

A major amount of hum and interference is created by computers, fluorescent lights, CFLs, LEDs, etc. It is absolutely amazing. I cannot play an AM Radio in my office, even with an external antenna unless I shut off the LEDs, computer, Displays, etc. There is noise even from the power company using the distribution wires as a carrier current path for the "Smart Meters, etc. Even taking a portable radio outside, when I get close to the house, the noise starts.

To diagnose, turn the volume down. If the hum is gone, your filters should be OK. However, take all of the advice from Fenbach and others about replacing all paper and electrolytic caps.

The controls that you are touching that change the sound: Are they the volume and tone controls, or are they the "Padder" caps for the tuning caps or IF transformer adjustments? If the latter, touching with a metallic screwdriver may change the level / quality of the sound depending if the screw is above ground potential. If merely touching the volume and tone controls, whose shafts are usually at chassis ground level, then try touching the case of the radio itself. If the change also occurs when touching the radio case, it is likely not at ground potential. Ground it, and touching the radio should not change performance unless you are between the radio and the signal.

Do ensure that you have an antenna of some sort connected to the radio. A vertical wire about 42" should work if you are not in the basement. This approximates the whip antenna used with the car, that your radio is trimmed to. However, a "long wire" antenna should work fine.

[Keefer]

Thanks guys.I did replace all caps.Have never tried an alignment.I only have soldering iron and multimeter so can't do alignment like I have watched on internet.The noise is when I touch volume and tuner with screwdriver.I will check the hum at lowest level.I think some of hum is in treble/bass control because it changes when I push control shaft in.I may be just too picky lol.Will try all suggestions.Also thank you officer for previous answer.Don't believe it has oz4.

[MrFixr55]

Hi Keefer,

The noise from touching the radio may go away when actually installed in a car. The radio case, frame and the user will all be at "equipotential' in the "Faraday Shield" that is the car body.

As for alignment, for an AM radio, if careful and mark where all adjustments were and be slow and gentle, one may be able to "peak" the IF stage by ear. There is a trimmer, usually on the frame of the radio to match the antenna to the radio. If the Radio is capacitor tubed, there will be trimmers on the tuning condenser. the trimmers for the RF can be peaked on a weak station midpoint and checked against the lower and upper limit of the band. the trimmer for the oscillator sets the beat frequency. touch thqat last and only if everything else has failed. Again, matchmark before adjusting, turn only a small amount at a time and if no effect, or adverse effect, return to original position. If the radio is inductively tuned instead of capacitively tuned, don't mess with it.

Good luck

[Keefer]

Thank you again.I also still have hum even when volume turned all the way down.I just replaced dual filter cap and didn't help at all.Will try an alignment and will do as instructed.Mrfixit the rectifier tube is 84.