Zenith H401 Radio buffs, help please..

[bwanna]

there are always folks coming into the antique mall trying to peddle something. such was the case sunday. this couple wanted to sell the radio you see pictured below. she told me it didn't work, "but alot of people like them for decoration". i asked what she wanted for it & she wanted to know what i would give her for it....we played that game for a while. finally i offered her $5. now all of a sudden the "mr." has a voice. he wants $10, i stuck at 5....he came down to $7.50. i stuck at $5. after saying again that alot of people like these old things for decoration, even if they don't work, they decided to take my 5bucks.

anyhoo....it is an attractive piece & i am wondering if anyone can give me a clue on how to make it work... currently it makes a buzzing noise when turned on.

thanks for your help.

[KeithB]

Donna, that's a very nice looking AM radio.  Just searching the web for Zenith H401 turned up <this PDF document> that includes a schematic, descriptions, and dial string routing diagram.  

The schematic shows four capacitors C13, C14, C15, and C16 in the power supply section.  I'd wager replacing those (relatively inexpensive) components would resolve the hum, unless there's also another problem.

[Wallphone]

It probably has some bad capacitors in it. Nothing an amateur like me or you could repair.
Dougpav

[bwanna]

thx for locating the schematics, keith. i could've done that but easier & more fun to get someone to do it for me .  i was thinking that plug looking piece needed something plugged into it to make it work. in the diagram it shows as battery plug...but no battery plugged in. it has a power cord so why does it have a battery plug anyway?

doug...me thinks you kidding w/me a bit....

[KeithB]

Dual-powered radios were common in the late 50s, as the fear of AC power loss (whether caused by natural disaster or nuclear attack) was so prevalent.  I remember my parents and grandparents always having several large lantern batteries at home for emergencies in the early 1960s.  

[Dennis Markham]

it has a power cord so why does it have a battery plug anyway?

So you can take it to the beach?

I'm sure Bingster, Dan/Panther, Bill Cahill and the other radio guys will chime on this one.  (I don't know if Keith and Doug are radio guys but may be, so I hope I didn't offend you guys).  I remember the warning to Kenny from Bingster the other day...something like you can hurt yourself......

Be careful poking around back there.

It is a cool radio.  Five bucks?  What can one buy any more for five bucks?  It was worth it (in my opinion).

[Shovelhead]

The plug is a battery plug. For lack of a better descrtion it is a two stage battery, two different voltages for different functions, one IIRC is about 90v.
Usually, at least on Zenith Trans-Oceanic radios you take the 110 wall plug and plug it into a female receptacle in the chassis, this trips a switch to allow the battery to power the radio and also takes the plug and as a safety device makes it impossible to plug the radio into a wall socket and play off the battery at the same time.

The buzzing is probably due to bad caps. Antique Radio Forum is a good place to go, several members here are also on there. Don't plug it in until this is corrected. It can get expensive not to mention a electrical hazard.  Not that hard to replace them, just read up on how to recap radios, just remember that there are high voltages in there, and never work on it or touch the chassis when it is plugged in.

[Dan/Panther]

Bwanna;
Dennis happens to have a close friend that lives in your area that repairs radios. I think Brian ?
D/P

[Greg G.]

Nice job on the dickering!  I want to take you with me next time I go treasure hunting.  

And I agree, very nice looking radio!

[Dennis Markham]

Donna, Brian (BDM on this forum) has been working on my Zenith, when time permits.  It's not finished yet so you can't use him until he's done with mine!

[KeithB]

I'd also guess those large batteries tucked neatly into the bottom of the portable plastic case...

[Bill]

The schematic shows that it has a selenium rectifier. They occasionally fail for no good reason other than age. You should probably disconnect it (you can physically remove it or not, at your whim), and substitute a silicon diode. You can get a 1-amp rectifier diode such as a 1N1004 or 1N4005 (but not 1N4003) from Radio Shack for less than a buck.

Bill

[Wallphone]

I remember seeing 45 volt batteries but never a 90 volt one. If you need 90 vdc to get the tubes going then you will probably need two 45's in series. According to this link that will set you back $36. (Ouch)
> http://www.batterycentralmall.com/Batteries/Eveready/Eveready.html <
Dougpav

[McHeath]

I don't know anything about how to make an old radio work so I'm no good there.  However I can certainly cheer on the radio's good looks and design!  It's a very cool setup and hopefully you can get it up and running nicely again. 

And of course I wonder about our music players of today, will anyone in 60 years be able to get a 2010 iPod to work? 

[KeithB]

I'd also guess those large batteries tucked neatly into the bottom of the portable plastic case...

When Donna posted the pictures last night, the first thought in my head was "Why on earth is the chassis mounted upside down in the body?!?"  It wasn't until I looked at it again this morning that I realized the probable reason all of that empty space was there.