Tube Radio Forum
Would you like to react to this message? Create an account in a few clicks or log in to continue.

1937 Detrola 146 with too much current through the electro-dynamic speaker coil

2 posters

Go down

1937 Detrola 146 with too much current through the electro-dynamic speaker coil Empty 1937 Detrola 146 with too much current through the electro-dynamic speaker coil

Post by acbaker123 Fri May 28, 2021 10:29 am

i have a 1937 detrola 146 that i have just about finished fixing, except I found that the speaker coil was getting warm. and the type 42 driver tube for it was also hotter than the rest. i originally took this to antique radio forums but nobody has responded. i used a 1.7k resistor and substituted it for the coil. i then measured the current being dissipated by the resistor at 56 milliamps and if I took the type 42 out it went down to 30 milliamps. i have also taken the .00025 resistor out of circuit and nothing changed. I even took all tobes except the 42 and 80 out and it still showed 50+ milliamps. i also still do not know if this is normal, I don't think it is though. i can post more pictures if you want.
shematic
viewtopic.php?p=3318709#p3318709

acbaker123
Member
Member

Number of posts : 81
Registration date : 2020-04-08

Back to top Go down

1937 Detrola 146 with too much current through the electro-dynamic speaker coil Empty Re: 1937 Detrola 146 with too much current through the electro-dynamic speaker coil

Post by acbaker123 Fri May 28, 2021 10:30 am

that link did not workhere is another 1937 Detrola 146 with too much current through the electro-dynamic speaker coil Detrol10

acbaker123
Member
Member

Number of posts : 81
Registration date : 2020-04-08

Back to top Go down

1937 Detrola 146 with too much current through the electro-dynamic speaker coil Empty Re: 1937 Detrola 146 with too much current through the electro-dynamic speaker coil

Post by mr_ed01 Fri May 28, 2021 2:12 pm

Speaker Coil:
   Any time you have a current flowing through a resistance (field coil resistance = 1600 ohms), heat will be generated.  A speaker field coil that is 'warm' to the touch is normal aoperating condition.  As long as the field coil resistance measures near the 1600 ohms specified it should be considered good.

B+ current:
  A B+ current of 60 to 70 ma is normal for a radio like that.  Most of the current will be consumed by the audio output stage.  The 42 tube, being a power output tube will run much hotter than any other tube (other than the 80) in the set.  This is a normal condition.  Touching that tube during operation can result in a burn.
Your post doesn't say if you have replaced all the 'paper' capacitors.  The .00025 is most likely a mica capacitor,  mica capacitors almost always are good and are usually not replaced.

mr_ed01
Member
Member

Number of posts : 128
Age : 77
Registration date : 2012-03-16

Back to top Go down

1937 Detrola 146 with too much current through the electro-dynamic speaker coil Empty Re: 1937 Detrola 146 with too much current through the electro-dynamic speaker coil

Post by Sponsored content


Sponsored content


Back to top Go down

Back to top


 
Permissions in this forum:
You cannot reply to topics in this forum