Measure the output before the speaker goes back. Leave the speaker off if the meter shows volts of DC. The right channel of this Sony HP-510A crackles with the volume knob doing nothing, which puts the fault after the volume control, in that channel's power amp. A bad part there can sit the output at a DC voltage. A speaker connected to that voltage burns.
The transistor guide is the hunt for the part. This page is the measurement that decides whether a speaker is allowed back on that channel. The repair on this unit is not finished, so this check is still ahead of reconnecting the right side.
What the meter is doing
| Check | Range | Stop if | Shop |
|---|---|---|---|
| DC at the output, no speaker, volume at zero | DC volts | The reading is volts, not a few tens of millivolts | View DC at the output, no speaker, volume at zero (affiliate) |
| The speaker itself, unplugged | Ohms | The reading is open, or near a short | View The speaker itself, unplugged (affiliate) |
| Current through a wire | The 10-amp jack, in series | You meant to measure voltage and the red lead is still in the amp jack | View Current through a wire (affiliate) |
Affiliate Link • Earns Commission
The measurement
Power the stereo through a dim bulb tester. No speaker on the channel you are testing. Volume at zero, mono off, tape monitor on Source.
Meter on DC volts. Red lead in the volt jack, not the amp jack. Red probe on that channel's positive terminal, black probe on the chassis or the negative terminal.
A reading that flickers around zero, a few tens of millivolts, is an output you can trust with a speaker. A reading of a volt or more is an output you do not connect. Power down through the bulb and go back to the part that was just changed.
The bulb is in series with the stereo for this power-up. A bright bulb that stays bright is a short. Shut it off. A bulb that flashes and settles dim is the condition where the DC reading means something.