zenith 7 s 633 tube radio - Videokarma.org TV - Video

markdi · #1 10-11-2010, 10:14 AM

my mom bought me a zenith 7 s 633 tube radio for 45 dollars.

the radio is complete and very very nice looking

she was working at a estate sale - she thinks I should be able

to resell it make some money and pay her back.

working ones sell for 250 or so.

the power cord was tucked inside the radio and I

know I should use a variac to power it up for the first time - replace caps -etc.

what does a good looking one - untested sell for ?

I do have the know how and tools to fix it.

my tools are in storage but I could make a light bulb current limiter and power it up.

I am unemployed and I have no money for parts.

I wish she would not have bought it.

marty59 · #2 10-11-2010, 12:11 PM

You need to inspect your radio before applying any power. Later pre-war radios were manufactured with lots of rubber insulated wire that crumbles and the last thing you need is a short. Also, a radio this age may have been repaired a time or two and you have to be suspect of any hack repairs.
Using a dim bulb tester is a good idea but do at least two things. Test first with the rectifier tube out, (measuring voltages a good idea) and if you wish to go any further you must make sure that the rectifier is good as well as the power supply electrolytic. Not sure on this year model, but if it uses a 6X5 Rectifier these tubes are notorious for shorting out and taking the transformer with it. And don't trust the original electrolytic either!

If the set fails any of these things, then you may want to set it aside until funds may improve. But at least you can assess it and make some determinations. You will put more labor into this than you can get out of it from a dollar point of view. Sometimes, it's assumed that you can make money doing something like this but that is not necessarly the case. And speaking from a hobbyist point of view to me (and others) it's more of a labor of love and enjoyment than making a buck.

markdi · #3 10-11-2010, 03:35 PM

it was made in 1942

this is what it looks like

http://radioattic.com/item.htm?radio=0111019

mine looks nicer

I wish my mom would not have bought it because now I owe her money for
it.

it is kinda kool looking

sampson159 · #4 10-12-2010, 06:50 AM

those late 30-early 40s zeniths are great!most cases a soft start on a variac and replace a few caps and thats it.transformers are critical.install a fuse or some kind of protection.i have several of these vintage zeniths and they are really great performers!

markdi · #5 10-25-2010, 01:47 AM

if the transformer is blown then the radio is toast - right ?

does anyone make a replacement transformer ?

I have not tested it yet.

dieseljeep · #6 10-25-2010, 08:51 AM

Those radios are great. Your's has the direct coupled triode output stage. If that radio is that nice it's definately worth restoring. I have a used transformer out of a year earlier model that should work. The only difference is that my transformer is a foot mount, while your's is a potted case. Please reply if interested. Dave. P.S. Test it first by removing all the tubes and apply power thru a 60W lamp.

markdi · #7 10-25-2010, 11:30 AM

I will try to test it really soon - like tonight

I am looking for work during the day

thank you

I will be looking for high voltages coming from the secondary -right

dieseljeep · #8 10-25-2010, 12:21 PM

Hi Mark. Best of luck on your job search. Power it up, see how bright the lamp gets. If it is dim, replace it with a 100W. and try again. If still dim, transformer should be OK. AC volts across HV winding should be 275 from each red lead to center tap, or 550 across both reds. Make sure 275 readings are reasonably balanced.

markdi · #9 10-25-2010, 02:25 PM

all I have is a 23 watt Compact Fluorescent will that work ?

...

markdi · #10 10-25-2010, 02:35 PM

I do know better

do stores even still have old style bulbs ?

if so I think I should stock up

Reece · #11 10-25-2010, 04:47 PM

Yes, you know better! No compact squiggle lights. Go get yourself some 40-60-75-100 watt bulbs, if only to have them around for a dim bulb tester. Bring it up first with dim bulbs and all tubes out. If you get up to 100 watt bulb with no overheating xfrmr., plug directly into the line.

If, after you have the tubes out, you have tested the volts coming out of high voltage, and the heater voltage, and the xfrmr does not get hot or smoke after leaving it on for ten minutes or so, plug in all the tubes EXCEPT the rectifier. Tubes should light. Leave it that way for a while and observe the xfrmr. Zenith was notorious for using somewhat light duty transformers, so yours might get more than warm, but should not exhibit signs of extreme stress...

Finally you could plug in the rectifier but WATCH because the electrolytics could be (probably are) bad and you could blow the rectifier or fry the xrmr. Be ready to yank the plug. Radio may play at this point, poorly or not. Don't play long: better to wait and change all the caps to be safe.

As stated before, check for any deteriorating rubber wiring as some could be shorted together. May need to replace some of this. Have fun!

marty59 · #12 10-27-2010, 05:26 PM

As mentioned, some of us here may be able to help you out if the transformer is bad. The part number will start with 95-xxx. I've been successful for finding Zenith Transformers using this site:

http://www.vintage-electronics.com/

I've posted this in the radio sticky besides other resources...

Good luck with your transformer!

markdi · #13 10-30-2010, 02:04 PM

I just got a new job on friday and I have crebrial palsey on my right side.

this job requires a ton of walking and standing all day.

my right ankle/foot was really really sore after about 6 hours at the new job.

I am surprised no one at the new job asked me what was wrong

I was limping a lot worse than normal - dragging my right foot - ha ha

I could barely walk when I got home last night.

getting out of my car was a real experience.

my foot seems fine now - no pain or anything.

I will be back at the new job on monday.

what does not kill ya makes ya stronger - right ?

this job might kill me

anyway

I should have some money to start working on this radio soon

and I should be able to keep it instead of selling it after I fix it.

once I get a paycheck or two I will be able to afford lightbulbs and a socket.

A cheap used digital camera would be kool too.

my car needs brakes and stuff.

how does the preset tuning work ?

some sort of adjustable ferrite slugs for each preset ?

is there a cover that comes off to get to the adjustments ?

I have not taken the radio apart at all.

I will wait untill I have some money to actually start working on it

I could use a old extension cord and a soldering iron and a cheap lamp from the goodwill to make a dim bulb tester.

markdi · #14 10-30-2010, 11:23 PM

is there a user's manual for this radio online some where ?

sales brochure ?

I wonder what it sold for new ?

I am sure there is a schematic - somewhere ?

AUdubon5425 · #15 10-31-2010, 12:08 AM

I have a '42 Zenith pamphlet - when I find it I'll scan the writeup for your set here.