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Old 23rd Jul 2020, 6:30 pm   #1
lloydwells
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Default Osram new music magnet 4. Battery connections and voltages help

I have an exceptionally tidy osram mm4 I don't usually do battery sets I could do with the following info what is the HT battery voltage PM2 fitted presumably output valve . Lt 4 volts I assume and what do I connect to SG I know it's screen what voltage and + - and where does the other connector from whatever battery it's attached to go ??
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Old 23rd Jul 2020, 7:41 pm   #2
ms660
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Default Re: Osram new music magnet 4. Battery connections and voltages help

HT will be somewhere around 120 volts, screen grid around 60 to 80 volts, LT should be 2 volts, grid bias....not absolutely sure but say 9 volts -ve for starters but possibly lower.

Plenty of info on this receiver on this forum, here's a link to the schematics for the battery version and the mains version:

http://www.electrojumble.org/DATA/Mu..._4_with_AC.pdf

Lawrence.
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Old 23rd Jul 2020, 8:02 pm   #3
Ed_Dinning
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Default Re: Osram new music magnet 4. Battery connections and voltages help

Hi lloyd, these set work well when operating and usually give little trouble apart from the I/V transformer which often has a winding OC.
Actual GB will depend on the OP valve fitted, and may be less than 9v, there is also an intermediate GB of 1.5 or 3 volts I believe.
High Z speaker needed

Ed
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Old 23rd Jul 2020, 8:09 pm   #4
lloydwells
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Default Re: Osram new music magnet 4. Battery connections and voltages help

Thanks that nearly answered the question which was where does my GB connect to lol
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Old 23rd Jul 2020, 8:15 pm   #5
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Default Re: Osram new music magnet 4. Battery connections and voltages help

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Originally Posted by lloydwells View Post
Thanks that nearly answered the question which was where does my GB connect to lol
It does actually answer the question.....in the link that was posted.

Lawrence.
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Old 24th Jul 2020, 9:03 am   #6
lloydwells
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Default Re: Osram new music magnet 4. Battery connections and voltages help

Ah I seem to have a bit of a lash up in the GB dept see pics from the article on the set GB is attached to the transformer and one side of the capacitor next to it mine had a wire from the transformer to a resistor where the fuse bulb should be please see pics
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Old 24th Jul 2020, 9:12 am   #7
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Default Re: Osram new music magnet 4. Battery connections and voltages help

Ah I seem to have a bit of a lash up in the GB dept see pics from the article on the set GB is attached to the transformer and one side of the capacitor next to it mine had a wire from the transformer to a resistor where the fuse bulb should be please see pics
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Old 24th Jul 2020, 9:40 am   #8
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Default Re: Osram new music magnet 4. Battery connections and voltages help

Have you checked the intervalve transformer yet? I had to rewind mine https://www.vintage-radio.net/forum/...d.php?t=158892.
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Old 24th Jul 2020, 9:57 am   #9
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Default Re: Osram new music magnet 4. Battery connections and voltages help

Quote:
Originally Posted by lloydwells View Post
Ah I seem to have a bit of a lash up in the GB dept see pics from the article on the set GB is attached to the transformer and one side of the capacitor next to it mine had a wire from the transformer to a resistor where the fuse bulb should be please see pics
It could be an auto-bias mod.

I would go with a GB battery.

Lawrence.
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Old 24th Jul 2020, 1:10 pm   #10
lloydwells
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Default Re: Osram new music magnet 4. Battery connections and voltages help

Transformer seems to be fine I'm going to disconnect the resistor and wire and put a battery in and see how we go.
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Old 24th Jul 2020, 7:38 pm   #11
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Default Re: Osram new music magnet 4. Battery connections and voltages help

Hi lloyd, the "flat cycle lamp batteries (LR12) and the adaptors that replace them and take 3, AA cells are good for this use and will fit into the clip for the GB battery.

Ed
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Old 25th Jul 2020, 12:40 am   #12
lloydwells
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Default Re: Osram new music magnet 4. Battery connections and voltages help

I've soldered 3 AA batteries together and printed them out an appropriate period grid bias battery box shouldn't ever need to change it so I'm sure that'll be fine .
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