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New to Electronics and Need a bit of help

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NightHawk95

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I have a AM 27MHz Receiver and it does not let power get through. I have ruled out all external sources of failure, and now have moved onto the internals. Nothing seems wrong, but I have noticed the 2 puddles of solder on the "Batt" input have flowed together. I assume they must be separate but can't find anyone to confirm this before I start making a mess.

When ever I apply power to the "Batt" terminal it I get an initial jolt then there is no presence of power after that.

Any help is much appreciated!

Thanks

-Mike
 

First, the best way would be to get a schematic.
If you can see two solder "puddles" close to the battery input, the two may belong to one lead while a third "puddle" to the other DC input lead.
Radios often have voltage regulators after the battery input terminal (connector). Find the regulator pinout and test the regulated voltage after it. Measure the DC current from the battery to see if it is excessive (a short) or too low. Connecting the battery may only charge a capacitor but the radio may then not get the current with a proper voltage.
Battery connector may be a "switching" type, which disconnects the DC power from AC/DC converter when you plug the battery connector in it. Those switches as well as "volume" regulator switches often fail.
I once repaired a nice AM/FM radio by replacing a 12 V Zener which regulated the voltage for RF stages while the audio section was OK.

Working without a schematic requires experience, and still often fails.
 
jiripolivka said:
First, the best way would be to get a schematic.
If you can see two solder "puddles" close to the battery input, the two may belong to one lead while a third "puddle" to the other DC input lead.
Radios often have voltage regulators after the battery input terminal (connector). Find the regulator pinout and test the regulated voltage after it. Measure the DC current from the battery to see if it is excessive (a short) or too low. Connecting the battery may only charge a capacitor but the radio may then not get the current with a proper voltage.
Battery connector may be a "switching" type, which disconnects the DC power from AC/DC converter when you plug the battery connector in it. Those switches as well as "volume" regulator switches often fail.
I once repaired a nice AM/FM radio by replacing a 12 V Zener which regulated the voltage for RF stages while the audio section was OK.

Working without a schematic requires experience, and still often fails.
Click to expand...

What ways are there to obtain a schematic of the part?
 

It's a tough one. Try the manufacturer, I would try a radio repair service. Sometimes they keep it for years.
You can try the "edaboard" forum, or google. Anything helps.

Your problem may be a simple one- a short or a bad switch. You may need to paint the voltage regulator schematic yourself.
 
jiripolivka said:
It's a tough one. Try the manufacturer, I would try a radio repair service. Sometimes they keep it for years.
You can try the "edaboard" forum, or google. Anything helps.

Your problem may be a simple one- a short or a bad switch. You may need to paint the voltage regulator schematic yourself.
Click to expand...

Thank you! I will check it out, I didn't want to start messing with things without a word of advice. I will post back if it works.
 

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