Im posting this in hopes that someone may be able to help me troubleshoot. I also want to bring context to my issue and a previous discussion on this forum that unfortunately didn't end in a "fix." the thread can be seen at this forum post linked below. aside from the squealing - this post summarizes my exact issue. for the most part, the audio i hear sounds clean, but just extremely low in the right channel. using line out on the back - both channels have equal audio signal. I'm hoping someone sees this and might be able to help me out.
previous post - https://www.boomboxery.com/forum/threads/new-owner-of-rx5150-left-channel-very-weak.28052/
Picked up a Panasonic RX-5150 with a very weak right channel. Left channel is strong and clear. Right channel is maybe 10% volume.
What I found / fixed already:
Complication:
Question:
Has anyone here actually fixed this exact weak single-channel problem on an RX-5150?
Since line out is clean on both channels, does this strongly point to the AF power amp/output section on these?
Any known common failure parts for one weak channel on this model?
previous post - https://www.boomboxery.com/forum/threads/new-owner-of-rx5150-left-channel-very-weak.28052/
Picked up a Panasonic RX-5150 with a very weak right channel. Left channel is strong and clear. Right channel is maybe 10% volume.
What I found / fixed already:
- Unit originally would only play properly when the record mute switch was depressed. (fixed by addressing record switch)
- Record mute slider was stuck. Cleaned it with DeoxIT and worked it back and forth until it moved freely. (restored playback without toggling rec mute)
- Cleaned all pots and switches I could access with DeoxIT 2x:
- volume
- balance
- bass/treble
- radio/tape switch
- other accessible controls
- Cleaned and reflowed the balance pot solder points.
- Cleaned headphone jack with ISO and deoxit - looks clean, no bent pins, transmits audio to headphones properly (low right channel signal volume).
- Repaired a cracked LED meter / TPS board by bridging broken traces. TPS seek now works correctly and lights properly, so that board seems functional again.
- Voltage selector on back is set correctly.
- Right channel is weak on tape
- Right channel is weak on radio
- Right channel is weak through headphones
- Right channel is also weak through the built-in speaker
- Balance control fully to the right does not bring the right channel up to normal
- Loudness button works in terms of changing overall sound, but does not fix the weak channel
- TPS button works, but has no effect on the weak channel issue
- Wiggling / twisting / pushing / pulling the headphone plug causes no change at all
- Line out is perfectly balanced left/right.
- I fed the Panasonic line out into another boombox line in and monitored through record mode, and both channels were equal.
- So the source/preamp side appears okay up to line out.
- Tape head issue
- Source selector/front end issue
- Voltage selector issue
- Speaker itself
- Headphone jack alone
- Cracked LED/TPS board as the main cause
- General dirty control issue, at least from the usual suspects
- Fault after the line-out split
- Right channel power amp/output stage problem
- Bad cap / transistor / resistor in the right output path (although the guy in the post above recapped the whole board and didnt get his weak audio fixed as a result)
- Cracked trace or bad solder joint somewhere in the right channel amp/output section (i would need help identifying where this is)
Complication:
- The solder side of the board is not easy to access and I am trying to avoid disturbing the radio dial string unless absolutely necessary.
Question:
Has anyone here actually fixed this exact weak single-channel problem on an RX-5150?
Since line out is clean on both channels, does this strongly point to the AF power amp/output section on these?
Any known common failure parts for one weak channel on this model?