Record Player Buzz

[pentium]

I found an absolutely ancient GE "transistorized" record player and aside from an unbalanced and excessively cheap pickup arm it has a real bad buzz. It's trying to amplify but more than anything the buzz overwhelms it. The amp circuit itself is very simple. Me being near the needle also seems to change the volume of the buzz indicating a ground loop, I believe.



Black cylinder on the right takes 120v in, there's four transistors, three capacitors and a bunch of resistors. It receives a signal straight from the needle and outputs straight to a speaker. Knobs control power and tone.
Never worked with amps before but my assumption is that after 40 years all the caps require replacement, correct?

[budm]

Re: Record Player Buzz

Have not work on one of these since the very early 70's. I thing it get the low voltage AC from the motor winding otherwise you will see big resistor to drop the 120Vac to about 12V. That large cap sitting between the two pots is the DC filter cap. The little black transistor sitting between the two push-pull out put transistors ( with heat sink on them) is for phase splitter/driver for the push-pull output section. The second medium size electrolytic cap is the DC blocker for the out put circuits to the speaker. The smallest electrolytic cap on the left is the input cap from for the phase splitter transistor. The small ceramic disk on the top left by the tone control pot is for the tone control circuits.
Yes, recap first. This amp may use Germanium transistors which has very high leakage which can cause a lot of problem such as low gain and draws a lot of current.

[kaboom]

Re: Record Player Buzz

And one side of the AC line goes right to that board- hot chassis. Look at the insulated pot shafts.

Check the carbon comps- they can drift upwards in value.