magnavox fm 43

12/19/2011 4:40:27 PMScott M.

I have a magnavox model fm 43 with what i think is an alignment issue. The am scale tunes in the station where it is located on the dial, but the fm section is almost half the scale off. It won't pick up the lower end from about 88 - 94.5 anymore either. If you turn the dial all the way down to 88, it will pick up the station on 95.7. The sound is still good no distortion that i can hear anyway. All the tubes test as strong on my tube tester. I was going to recap the set but it has mostly ceramic disc caps in it, only about 2 or 3 paper caps and the electrolytics have been replaced before i received it. The dial mis-alignment has gotten worse since i've owned the radio, I used to be able to receive 93.7 when I first purchased it, but the scale was still off back then too. I am looking for any kind of advice any one may have (except for throwing it out). I know it's not a valuable or rare item, but it was the radio that started a collection of close to thirty radios now. And if anyone could point me towards the schematic i would be grateful.

12/23/2011 12:04:23 PMBill G.

Hi Scott,
I hope my response isn't too late.
I do a lot of Zenith H723 and had one with a problem much like yourse.
The problem turned out to be that the oscillaor coil had shed some of its metal coil and the threads from that shedding had lain close to the coil, changing its tuning.
I know it is bizaar, but a problem like this doesn't have an ordinary solution like a drifted capacitor or a tube with a loose grid. That is what it was, an oscillator coil that was shedding.
The fix was to replace it in my case because I had another oscillator coil. If you do not, and see the shedding, try cleaning any stuff off of it and retuing it.

Good Luck and Happy Holidays,

Bill Grimm

12/23/2011 4:48:21 PMEdd

Sir Scott Emmmm . . . . .

Looking at your unit reveals it not having the open an accesssible FM oscillator coil and tuning condenser as the Zenith 723 . .et al series do.

As per :

With your unit using a sealed up "pot metal " housed FM tuner module .
Note the large pulley drum on the AM tuning condenser and that the dial cord is concidentally routed over to also rotate the pulley of the the FM tuner.

Naturally the AM tuning is going to rotate 180 degrees between its tuning range, but also place a tick referencing marker on the smaller pulley on the FM unit and see that it also is making a 180 degree transit thru its tuning range.

By memory . . .seems like that FM unit is involving gearing and may be of fiber and the FM init may have "slipped timing" of its interface to the dial cord.

Since that mentioned dial error is soooo great.

73's de Edd

Beauty is in the eye of the beer holder.

:Hi Scott,
: I hope my response isn't too late.
: I do a lot of Zenith H723 and had one with a problem much like yourse.
: The problem turned out to be that the oscillaor coil had shed some of its metal coil and the threads from that shedding had lain close to the coil, changing its tuning.
: I know it is bizaar, but a problem like this doesn't have an ordinary solution like a drifted capacitor or a tube with a loose grid. That is what it was, an oscillator coil that was shedding.
: The fix was to replace it in my case because I had another oscillator coil. If you do not, and see the shedding, try cleaning any stuff off of it and retuing it.
:
:Good Luck and Happy Holidays,
:
:Bill Grimm
:

12/23/2011 8:28:39 PMBill G.

That looks like a really good possibility to me!

Best Regards,

Bill Grimm

12/24/2011 3:44:30 PMScott M.

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:Edd, You saved the day again! Thats exactly what it was. Radio is now playing all the stations where they are supposed to be on the dial after a little adjustment. Thanks for everyones help. Bills reply resulted in a much cleaner inside, which it badly needed. Thank you both!
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:Sir Scott Emmmm . . . . .
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:Looking at your unit reveals it not having the open an accesssible FM oscillator coil and tuning condenser as the Zenith 723 . .et al series do.
:
:
:As per :
:
:
:

:
:
:
:With your unit using a sealed up "pot metal " housed FM tuner module .
:Note the large pulley drum on the AM tuning condenser and that the dial cord is concidentally routed over to also rotate the pulley of the the FM tuner.
:
:
:Naturally the AM tuning is going to rotate 180 degrees between its tuning range, but also place a tick referencing marker on the smaller pulley on the FM unit and see that it also is making a 180 degree transit thru its tuning range.
:
:
:By memory . . .seems like that FM unit is involving gearing and may be of fiber and the FM init may have "slipped timing" of its interface to the dial cord.
:
:
:Since that mentioned dial error is soooo great.
:
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:
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:73's de Edd
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:Beauty is in the eye of the beer holder.
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::Hi Scott,
:: I hope my response isn't too late.
:: I do a lot of Zenith H723 and had one with a problem much like yourse.
:: The problem turned out to be that the oscillaor coil had shed some of its metal coil and the threads from that shedding had lain close to the coil, changing its tuning.
:: I know it is bizaar, but a problem like this doesn't have an ordinary solution like a drifted capacitor or a tube with a loose grid. That is what it was, an oscillator coil that was shedding.
:: The fix was to replace it in my case because I had another oscillator coil. If you do not, and see the shedding, try cleaning any stuff off of it and retuing it.
::
::Good Luck and Happy Holidays,
::
::Bill Grimm
::
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