No one conducts individual parts replacement, it has changed to board swappers for many years now.
90% of the Electrolytics were outside 20% tolerance
80& of the Transistors were very low HFE, below 50
80% of the Resistors were outside 5% tolerance
Drivers and Outputs are random and not the same, plus low Hfe
Also see post 44 & 46 as an example of the Ceramics
From DCA75PRO manual:
Now give that fact a loooonnnngggg consideration and answer yourself.
1) you pulled 100% of components from that complex amplifier?
What for?
2)
Post #44 says or asks nothing.
Except meriting the trivial answer: "well, they certainly look like ceramics"
What kind of answers were you expecting?
Post #46 seems to worry about something irrelevant.
MY question is: "what is your REAL problem?
What are you trying to repair?"
If I understand the value of 104 it should be .1uf but they all measure to be around .067uf, am I missing something? Doesn't post 49 & 50 answer the question?From DCA75PRO manual:
Now give that fact a loooonnnngggg consideration and answer yourself.
1) you pulled 100% of components from that complex amplifier?
What for?
2)
Post #44 says or asks nothing.
Except meriting the trivial answer: "well, they certainly look like ceramics"
What kind of answers were you expecting?
Post #46 seems to worry about something irrelevant.
MY question is: "what is your REAL problem?
What are you trying to repair?"
If there’s one important thing I’ve learned in my life it’s that the old saying is true. If it aint broke then don’t fix it.
Is your goal to replace every single component with and see how the amplifier sounds?
Find the resistor value and wattage you need. Sort by cheapest first. That’s how consumer electronics are designed.
Is your goal to replace every single component with and see how the amplifier sounds?
Find the resistor value and wattage you need. Sort by cheapest first. That’s how consumer electronics are designed.
Those 0.1uF discs were likely Z5U dielectric, so tolerance no better than 20%, and dielectric constant varies with temperature, applied voltage, maybe even the phase of the moon (just joking for that one). I also would not be surprised if the Z5U dielectric also has aging effects. They are useful for power supply bypass and not much else.
Boyoboyo - I just searched and found that the Z5U dielectric drops off by around 6% per decade of time. COG is stable with time, X7R less so. Add that to the 20% tolerance the cap already has....
Boyoboyo - I just searched and found that the Z5U dielectric drops off by around 6% per decade of time. COG is stable with time, X7R less so. Add that to the 20% tolerance the cap already has....
On the subject of ceramic capacitors. A property I was not aware of until recently is how much capacitance can vary with voltage. Scroll to the bottom. https://ibex.tech/resources/geek-area/electronics/capacitors/ceramic
Z5U capacitors are also piezoelectric - I found out the hard way when I tried using them for energy storage in an experimental ArF excimer laser. They did not appreciate being discharged form 10-20 kV in 50 nsec, and once in a while, one would crack. This meant we had to disassemble the laser and hipot each and every cap to find the bad one. They got replaced with a more reasonable dielectric like N4700.
In my last job, one of our customers complained about acoustic noise emanating from the Z5U Y caps we were using as RFI filters in one of uor custom power supplies, and we had to replace the caps with film-based Y caps.
In my last job, one of our customers complained about acoustic noise emanating from the Z5U Y caps we were using as RFI filters in one of uor custom power supplies, and we had to replace the caps with film-based Y caps.