redpackman
Active Member
I have a KA-8300 I've had for years. It has been my trusty workhorse and done very, very well. I put in a new relay some years ago and did a partial recap at that time too. It played well and behaved perfectly since then until recently. I turned it on one day and I immediately hear light "thunderstorm" static in the right channel. Wow, that's new! I fiddled with the levers and switches with no change. I just let it continue to run. Changing the volume made no difference at all. I could hear it no matter the position of the knob including completely down/volume off. I checked the combined/separate switch. I usually have it in the combined mode. I also have good heavy copper jumpers connecting the amp and pre-amp secitons. I noticed that if I pulled out the copper jumpers and moved the switch to "separate" the thunder sound grew inoticeably louder.
I let the amp run for awhile and the sound, over about half an hour slowly, gradually diminished. Then it simply went away and I could get signal and music in both channels. For awhile though the program music was dominant I couldstill hear a little static sound, but then after a few more minutes the static/thunder just stopped and all was well. From the time I turned on the amp until the sound was perfectly clear with no interference was about half an hour to forty minutes.
Tonight I took off the top and bottom covers and reflowed the solder points in the right channel power amp section since it was so available and I'd guessed that the fault was in the amp rather than the pre-amp section. I'd taken a jumper pair and switched the connectors between the separate combined RCA female connectors whether A to A and B to B or A to B and B to A the distorted sound stayed always in the right channel. That indicated to me that the power amp section was the problem. But I'm only a very amateur amateur, so am WIDE open to corrections.
Using a dim bulb tester after re-flowing the solder I fired it up. No change. Light thunder in the right channel. Using a plastic screw driver handle I tapped here and there around the now open circuits. I'd tried that before on a bad amp and pretty quickly found a "noisy" transistor. The tapping made no apparent difference. Still thunder, but perhaps now a tiny bit quieter with occasional louder clicks and pops not at all connected with my tapping. I also used some "canned air" to spray on the components in the right channel power amp section. No change. But on the other hand as it "warmed up" over time the thunder diminished and then was mostly gone and I could play the music with both channels sounding pretty good. When I turned the volume all the way down the program material in the left channel was completely silent. In the right channel with the volume all the way down the program material was totally off too, but there was still a little light thunder. Then, as before, after a few more minutes all the static/thunder stopped fully and both channels were nice and clear.
Thoughts, suggestions, ideas, questions? Are any of the components in the power amp section more likely suspects?
I let the amp run for awhile and the sound, over about half an hour slowly, gradually diminished. Then it simply went away and I could get signal and music in both channels. For awhile though the program music was dominant I couldstill hear a little static sound, but then after a few more minutes the static/thunder just stopped and all was well. From the time I turned on the amp until the sound was perfectly clear with no interference was about half an hour to forty minutes.
Tonight I took off the top and bottom covers and reflowed the solder points in the right channel power amp section since it was so available and I'd guessed that the fault was in the amp rather than the pre-amp section. I'd taken a jumper pair and switched the connectors between the separate combined RCA female connectors whether A to A and B to B or A to B and B to A the distorted sound stayed always in the right channel. That indicated to me that the power amp section was the problem. But I'm only a very amateur amateur, so am WIDE open to corrections.
Using a dim bulb tester after re-flowing the solder I fired it up. No change. Light thunder in the right channel. Using a plastic screw driver handle I tapped here and there around the now open circuits. I'd tried that before on a bad amp and pretty quickly found a "noisy" transistor. The tapping made no apparent difference. Still thunder, but perhaps now a tiny bit quieter with occasional louder clicks and pops not at all connected with my tapping. I also used some "canned air" to spray on the components in the right channel power amp section. No change. But on the other hand as it "warmed up" over time the thunder diminished and then was mostly gone and I could play the music with both channels sounding pretty good. When I turned the volume all the way down the program material in the left channel was completely silent. In the right channel with the volume all the way down the program material was totally off too, but there was still a little light thunder. Then, as before, after a few more minutes all the static/thunder stopped fully and both channels were nice and clear.
Thoughts, suggestions, ideas, questions? Are any of the components in the power amp section more likely suspects?
