Need help from Vintage Radio buffs

[Scott_Conger]

Recently, I purchased a vintage Zenith Trans-Oceanic portable (23lbs!) radio. It's in beautiful physical condition and functions (until yesterday) perfectly.

Chronology of events:

• The radio worked perfectly for about 8 days as I learned how to manipulate the controls to receive all forms of SW, VHF, Broadcast, etc.
  yesterday as I was listening to SSB, using the controls as directed by manual (volume up full, sound controlled with Gain Control), I moved the dial too quickly to an unexpectedly strong station and the radio went full blast volume for the second it took to get off of the station.

• That same day, as I turned the radio "off" with the on/off - volume switch, there was a terrible static roar which quickly diminished after about 1/2 to 1 second (after the radio was switched "off"). To be specific, as I reduced the volume down to total silence, there was no static, but the moment I "snapped" it off, the noise explodes out the speaker and spends about a second after shut off, diminishing in volume, down to nothing. It seems like there is power which is not properly being shunted (?) somewhere safely.

• For those 8 days, and prior to this event, everything remained operating "perfectly"

this radio has not been restored, has all original electrolytic capacitors and the potentiometers all are "silent" when run through their range - the only problem is a crash of static during and slightly after it is switched off.

I would like to believe that by running the volume through its full range the other day I have dislodged some grunge which will simply clean up with Deoxit but am also fearful that the coincidental "full volume blast" either stressed or killed some unknown (to me) component.

I'd greatly like to hear from someone who has radio/TV experience who could offer advice (and encouragement!) as my playtime has come crashing down in ruin. Please consider contacting me via email so as to not bother other folks who are not interested in this topic. Thanks.

[TXGOAT2]

Old radios are wonderful things. There are a number of antique radio service and hobby sites on the internet where advice, parts, literature and service can be found. I don't know of any specific ones, but a few searches should turn up some leads.

Edit:
Try www.antiqueradio.org

[Norman Kling]

If you have an electro-dynamic speaker on the radio, you could have an electrolytic capicitor discharging through the speaker.
Norm

[Scott_Conger]

This AM update:

on/off/volume switch operates perfectly fine today. Those kind of components, while they get dirty over time, do not usually instantly go bad or suddenly heal, so I suspect that Norm is on to the problem.

I have a re-cap kit sitting in the mailbox today and it may be that I am soldering new caps in later in the week...I just wish I could figure out which one to avoid a lot of work replacing them all. I have the factory manual/schematic but there are 4 identical switches and darned if I can figure out through tracing, which one is which to figure out the correct circuit/caps.

thank you for looking

[TXGOAT2]

Sometimes elements within a vacuum tube can loosen and cause odd behavior. Very lightly tapping each tube with the radio on with something like a pencil might isolate such a problem.

[Jerry VanOoteghem]

Sometimes elements within a vacuum tube can loosen and cause odd behavior. Very lightly tapping each tube with the radio on with something like a pencil might isolate such a problem.

It's a later Trans-Oceanic. Solid state.

[Jerry VanOoteghem]

I have a re-cap kit sitting in the mailbox today and it may be that I am soldering new caps in later in the week...I just wish I could figure out which one to avoid a lot of work replacing them all.

It's best to replace them all. When caps go bad, they usually short out. When they short, there's always some other component that does not like a shorted cap and so that component fails as well.

A while back, I bought a late 30's radio on eBay. Incredibly, it was delivered without being damaged in shipping, a 50/50 chance. I couldn't wait to try it out. It played great... for about 30 seconds. Then POP & silence! An electrolytic capacitor shorted and blew the transformer. The thing is, I knew better than to just power it up. It sits on my bench, staring at me, and the only sound it makes is in my mind, where it says, "stupid!"

[Phoenix88R]

Seems like you have it fixed. For others and future reference folks on this site https://antiqueradios.com/forums/index.php are very knowledgable and helpful, much like the MTFCA.

[Robert Kiefaber]

Needs complete recap.

[Norman Kling]

Some of the earlier electrolytic capacitors are fluid filled with a pin hole at the top to let gasses expel. If you lay that kind of radio on it's side or back the fluid will escape from the capacitor. That can ruin the capacitor. The radio should be shipped standing upright.
Norm

[Scott_Conger]

last update

static-y CRASH upon turn off is louder the longer the radio is played (at any volume)

on and off in 5 minutes at listenable volume results in a small "crash"

on and off after 3 hours at listenable volume results in a thunderous "crash"

new caps it is, then

thanks to everyone who commented

[Michael Peternell]

I have a re-cap kit sitting in the mailbox today and it may be that I am soldering new caps in later in the week...I just wish I could figure out which one to avoid a lot of work replacing them all.

It's best to replace them all. When caps go bad, they usually short out. When they short, there's always some other component that does not like a shorted cap and so that component fails as well.

A while back, I bought a late 30's radio on eBay. Incredibly, it was delivered without being damaged in shipping, a 50/50 chance. I couldn't wait to try it out. It played great... for about 30 seconds. Then POP & silence! An electrolytic capacitor shorted and blew the transformer. The thing is, I knew better than to just power it up. It sits on my bench, staring at me, and the only sound it makes is in my mind, where it says, "stupid!"

[tdump]

If it is like my vietnam era Zenith trans-oceanic the transistors are in sockets and i had 1 be a bit loose in the socket. But as for the caps, I can't answer in detail on that particular radio ,but replace all the caps, they are all the same age.

[Scott_Conger]

Thank you Mack

This is a couple years newer than yours, but the layout is nearly identical to yours and also has the transistors mounted in sockets. They will all receive a thorough cleaning and possibly a few selective replacements if necessary, as the new/replacement transistors are quite inexpensive and readily available (once you figure out the zenith/modern cross-references).

[Jerry VanOoteghem]

Thank you Mack

This is a couple years newer than yours, but the layout is nearly identical to yours and also has the transistors mounted in sockets. They will all receive a thorough cleaning and possibly a few selective replacements if necessary, as the new/replacement transistors are quite inexpensive and readily available (once you figure out the zenith/modern cross-references).

You transistor guys...

If it don't glow, it don't go!

[tdump]

Thank you Mack

This is a couple years newer than yours, but the layout is nearly identical to yours and also has the transistors mounted in sockets. They will all receive a thorough cleaning and possibly a few selective replacements if necessary, as the new/replacement transistors are quite inexpensive and readily available (once you figure out the zenith/modern cross-references).

You transistor guys...

If it don't glow, it don't go!

tube.jpg

Oh wow,foot warmers!