Hello to all,

Im new in this forum. I recently acquired a Panasonic RF-1130 transistor radio. It is a nice tabletop radio with FM-AM-LW-SW bands and phono connection. It has a gyroscopic antenna and a kind of fine-tuning knob which works great in the SW bands.

For a picture you can visit http://herculodge.typepad.com/herculodg ... mfmsw.html

The radio plays great with only one problem: there is a constant hiss coming out from the speaker immediately after the set is switched on, it does not change with volume and is constant, no matter where the band selector is. it is even there when I turn the radio to Phono mode.

I saw in other posts that this might be because of faulty resistors or transistor in the output stage.

Does anyone have the schematic of this radio on the basis of which i can check values of components?
If the problem is a transistor, can replacement transistors be found in electronics shops?

I am very experienced with tube radios, but this is my first solid state radio and I need some help!
thanks!
nik

Hi Nik - Welcome to the ARF forums!

Can't find a schematic in the Sam's Photofact Series.
Not sure where you'll find one except maybe here:
http://www.manuals-in-pdf.com/index.php ... ward=plist

Replacing the electrolytic capacitors and reflowing any suspicious solder joints might help.
Don't know what else to offer you.

~ Mitch ~

I would check the amplifiers preamp transistor . Almost every radio i had with that hiss problem was the preamp transistor . If the transistor has a metal case you can touch it with a hot soldering iron to heat up the transistor and listen for changes .

Dried-out speaker coupling caps can cause the output transistors to draw excessive current and possibly increase the noise level.

Agreed on the 1st audio or driver transistor as a likely cause. I have had that happen a couple of times. The first time it took me about a month to figure it out and I tried everything BUT that.

Brett