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Antique Radio Technical Forum
Zenith 7J232 lost oomph

Posted by Norm Leal on 02/09/2012 19:40

Dave

Good to hear you found the problem.

http://www.nostalgiaair.org/PagesByModel/317/M0025317.pdf

Number 1490 bulbs can be used:

http://www.bulbdirect.com/products/product.php?item_id=2346&cat_id=

They are half of a #47. A #45 draws .5 amps. This will cause too much filament voltage across the 19 tube. Current rating is important in a series circuit.

Norm

:Norm,
: I was studying the schematic when I noticed that the filament of the 1J6 is in series with the two dial lamps. There are shunt resistors 21 ohms, but if a dial lamp burns out the filament voltage on the 1J6 will be too low, causing that problem.
: Do you have 2 2.9 volt bayonet bulbs? If not I'll try to find 2 #45 bulbs.
: I put in a # 47 bulb temporarily and the Oomph is back. So that problem is normal if the dial lamps burn out in a Zenith 7J232. The "mystery" is solved. Filament voltage is back to 2.
:
:Thanks,
:
:Dave
::Dave
::
:: 1J6 is unusual in some ways. It can operate with zero grid bias. With some bias it draws little current. When you are testing the tube be sure filament is 2 volts.
::
:: 1J6 is rated to 135 volts. You might be reading higher voltage because the 1J6 isn't drawing hardly any current? See if voltage is lower with a new tube. I have some here if you have a hard time getting a 1J6.
::
:: http://frank.pocnet.net/sheets/084/1/1J6G.pdf
::
::Norm
::
:::Hello Again All,
::: I tested the 1J6 on my SECO model 107 tube tester and it tests very very weak. It's maybe up to 3%. But I don't have another one to try. So I have to order one.
::: It WAS playing ok last night, so I suspect that one of the old resistors failed. Also I see 210 volts on each plate. Is that too high?
:::
:::Thanks,
:::
:::Dave
::::Hello All,
:::: When I turned on the radio today it refuses to play loud. The sound is good but if you try to turn it up it distorts but won't get loud. All B+ voltages are good. Where should I look? I replaced all paper and electrolytic capacitors. Nothing is touching that shouldn't. This is very odd. It would be odd that the 1J6 is failing.
::::
:::: Please help if you can.
::::
::::Thanks,
::::
::::Dave
::::
:::
:::
::
::
:
:




Zenith 7J232 lost oomph 
Dave Froehlich  02/09/2012 14:51 
Dave Froehlich  02/09/2012 15:29 
Norm Leal 02/09/2012 16:00 
Dave Froehlich  02/09/2012 16:06 
Dave Froehlich 02/09/2012 16:12 
Dave Froehlich  02/09/2012 17:22 
Edd 02/09/2012 18:15 
Dave Froehlich 02/09/2012 20:58 
Norm Leal 02/09/2012 23:21 
Dave Froehlich 02/09/2012 18:31 
Norm Leal 02/09/2012 19:40 

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