Continuing from my previous thread, I moved on to beginning the recap and mods. Everyone has been very helpful, even before grabbing the solder. I much appreciate that.
I managed to get the main filter caps (went with 6800uF), head amp, tone blocks (with kev's preamp mod) accomplished this weekend.
I had a few of questions tho.
1. Do all the later revisions have this small, blue 1(M) 25V electrolytic cap in place of the mylars? See pic. I initially followed the service manual and swapped them for poly 0.47uF, but after observing #4 (below) I swapped those little guys back in. A 1uF film cap should be a suitable replacement, right?
2. After plugging everything in to ensure things were still working, I noticed one channel was dead. I looked over my work and realized that one of the KSA992's had a little tiny piece of solder bridging the leads. I removed it, checked it in diode mode (appeared to read fine, wasn't shorted), and now both channels work. Do you think I need to check anything else to ensure everything is alright? Any voltage checks?
3. I set the DC offset and went to try the bias, following the manual, and I think I turned the trim the wrong direction. One heatsink started to warm up pretty quick. I didn't see any smoke, and it still seems to work just fine, so that's good. But, when I went to try and read the voltage across the resistors on the filter boards (to set it at 13mV), I'm getting 0V at that location on both sides -- regardless of the bias trim.
4.The phono section is very very quiet. Max volume is silent. The only way to hear anything is to use a line-level device (I had it's output set to very low). And of course, if I turned it up a bit on the line level, it sounded both quiet and distorted. I'm guessing due to clipping. But, why is my head amp extremely quiet..?
I'm glad I decided to test things half way through.. makes troubleshooting a bit easier. The line level sections do sound pretty good, tho. Hard to tell in the limited time I had it on if there's any night and day improvements... The amp is probably out of bias and there could be something else going on with it, but the fact that it sounds as great as it does in this state is very promising.
Looking forward to any help!!
I managed to get the main filter caps (went with 6800uF), head amp, tone blocks (with kev's preamp mod) accomplished this weekend.
I had a few of questions tho.
1. Do all the later revisions have this small, blue 1(M) 25V electrolytic cap in place of the mylars? See pic. I initially followed the service manual and swapped them for poly 0.47uF, but after observing #4 (below) I swapped those little guys back in. A 1uF film cap should be a suitable replacement, right?
2. After plugging everything in to ensure things were still working, I noticed one channel was dead. I looked over my work and realized that one of the KSA992's had a little tiny piece of solder bridging the leads. I removed it, checked it in diode mode (appeared to read fine, wasn't shorted), and now both channels work. Do you think I need to check anything else to ensure everything is alright? Any voltage checks?
3. I set the DC offset and went to try the bias, following the manual, and I think I turned the trim the wrong direction. One heatsink started to warm up pretty quick. I didn't see any smoke, and it still seems to work just fine, so that's good. But, when I went to try and read the voltage across the resistors on the filter boards (to set it at 13mV), I'm getting 0V at that location on both sides -- regardless of the bias trim.
4.The phono section is very very quiet. Max volume is silent. The only way to hear anything is to use a line-level device (I had it's output set to very low). And of course, if I turned it up a bit on the line level, it sounded both quiet and distorted. I'm guessing due to clipping. But, why is my head amp extremely quiet..?
I'm glad I decided to test things half way through.. makes troubleshooting a bit easier. The line level sections do sound pretty good, tho. Hard to tell in the limited time I had it on if there's any night and day improvements... The amp is probably out of bias and there could be something else going on with it, but the fact that it sounds as great as it does in this state is very promising.
Looking forward to any help!!