New here, first Sansui AU-719
- Thread starter Mk1mk
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bolero
Super Member
Amazing! thx for posting the progress, very informative! I have been wondering about the bipolar replacements of 2x polar I've seen occasionally
I noticed on the preamp board C36,40 & C37,41 are different compared to original: are the smaller replacements a different type of capacitor? Or just smaller value?
I noticed on the preamp board C36,40 & C37,41 are different compared to original: are the smaller replacements a different type of capacitor? Or just smaller value?
Actually, one of them is a larger value, originals were 100uF, + 47uF the replacements are 220uF, + 47uF.
Those capacitors filter the power supply to the board. With the Phono stage having the higher sensitivity, preventing modulation of the power supply is a key consideration.
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Yes, there are 4 of these 100µF/47µF pairs - all for filtering the +ve and -ve rails.
Bright_Star
Active Member
When it comes to doing Restorations, the two things that someone needs to have is knowledge & skills, the knowledge being
Electronics/circuit theory, and the skills being handy with tools and the use of test equipment. Its hard to be successful unless
someone is fairly good at both, vs just one but not the other. For me, electronics and the theory I learned/studied in college
was not so hard, but the hands-on stuff does not come as easy to me, whereby tools and the mechancial aspect of taking things
apart to repair is more of a challenge. Then again, put a guitar in my hands, and I can play fine (since I started at age 12. 61 now).
Thus, I want to point out, (as an example) checking the bias might seem easy to do, but if someone has never done so before, you need to be cautious.
The amp is powered on to take the measurement, and in a densly packed amp, it might not be so simple to attach a meter probe to the
test point inside, and all it takes is for that lead to snap off and accidentally short something out, and in the blink of an eye, you caused
extra problems to fix, instead of doing anything beneficial.
Those trim pots have probably not been touched since it left the factory new back in 1979-80. They can be very hard to adjust to a steady value,
thus even the slighest attempt to turn it could send the reading all over the place or put the amp into protection mode. Just some things to be aware of
if a novice has ideas of doing such tasks on their own.
The 719 is a good amp, though I think I prefer the AU-717. I also have an AU-519, I like that it has the flexibility to be used as a preamp if need be, being it has pre out-main in capability, which is not on the 'higher' model 719, go figure how Sansui decided these things on why certain models have them but others dont. Ditto AU-317 vs 417, or 317 II.
Electronics/circuit theory, and the skills being handy with tools and the use of test equipment. Its hard to be successful unless
someone is fairly good at both, vs just one but not the other. For me, electronics and the theory I learned/studied in college
was not so hard, but the hands-on stuff does not come as easy to me, whereby tools and the mechancial aspect of taking things
apart to repair is more of a challenge. Then again, put a guitar in my hands, and I can play fine (since I started at age 12. 61 now).
Thus, I want to point out, (as an example) checking the bias might seem easy to do, but if someone has never done so before, you need to be cautious.
The amp is powered on to take the measurement, and in a densly packed amp, it might not be so simple to attach a meter probe to the
test point inside, and all it takes is for that lead to snap off and accidentally short something out, and in the blink of an eye, you caused
extra problems to fix, instead of doing anything beneficial.
Those trim pots have probably not been touched since it left the factory new back in 1979-80. They can be very hard to adjust to a steady value,
thus even the slighest attempt to turn it could send the reading all over the place or put the amp into protection mode. Just some things to be aware of
if a novice has ideas of doing such tasks on their own.
The 719 is a good amp, though I think I prefer the AU-717. I also have an AU-519, I like that it has the flexibility to be used as a preamp if need be, being it has pre out-main in capability, which is not on the 'higher' model 719, go figure how Sansui decided these things on why certain models have them but others dont. Ditto AU-317 vs 417, or 317 II.
