I have a Musical Fidelity X10-D that is blowing capacitor C8. The unit became noisy, so I took a look and noted that C8 was swollen at the top. I replaced it and C4 for good measure, and the new one did the same after a day. So now I'm figuring there is an issue elsewhere, causing this problem with the capacitor in C8 position, but I'm not sure what I should be checking(?) Any guidance is appreciated.
2023-02-08_08-04-10 by Barry, on Flickr
2023-02-08_08-04-10 by Barry, on Flickr
I was looking around for a schematic and found an old thread here. https://www.diyaudio.com/community/threads/musical-fidelity-x10d-schematic.98207/
Scroll down to the bottom of page 1 and see post #20 where @gingertube replaces all the 35v caps in the PS with 50v.
jeff
Scroll down to the bottom of page 1 and see post #20 where @gingertube replaces all the 35v caps in the PS with 50v.
jeff
What are the DC voltages on those capacitors? Also on C2 and C6? Anything over 25VDC?
Maybe the voltage doubler is not working right.
Maybe the voltage doubler is not working right.
It would be very difficult for C8 to be caused to fail, without more problems upstream of it.
Check the entire power supply. Perhaps the caps in the voltage doubler are bad.
Have you not done any further checking?
Check the entire power supply. Perhaps the caps in the voltage doubler are bad.
Have you not done any further checking?
Very difficult for me to test on my own, tough to hold meter leads on board and plug it in at the same time. Maybe when someone else is home.
Sorry, I'm a total n00b with this stuff. I can take measurements, and replace parts as directed, but that's about the extent of my current abilities. Trying to learn...
I did measure the wallwart, and that was 13.2v AC, which is up a bit from the stated 12v AC. Wall voltage is also a bit hot today @124
Next check C1, C2, C5, C6, and all of the diodes. One of those parts may be shorted.
The C8 will certainly not fail for no reason, twice in a row.
The C8 will certainly not fail for no reason, twice in a row.
Yup, 12.5 when connected to the unit, thanks!
C1 16.7v DC
C5 16.9v DC
C2 32.3v DC
C6 31.3v DC
D1 12.3v DC
D2 16.9v DC
D3 15.4v DC
D4 15v DC
D5 16.4v DC
D6 .45v DC ???
And thanks for the guidance and advice!
D6 is for the pilot light. No problem.
Are these the DC voltages across each part, or to ground?
The C2 and C6 caps should be rated at 50VDC for obvious reasons.
Still no reason for the second failure of C8, unless you installed it backwards. Did you?
Are these the DC voltages across each part, or to ground?
The C2 and C6 caps should be rated at 50VDC for obvious reasons.
Still no reason for the second failure of C8, unless you installed it backwards. Did you?
To ground.
All the caps in this part of the board are 35v, but there are a few different farad ratings.
No, I installed it with the same polarity as the one it replaced. Unless it was installed improperly, but the unit had functioned for over a decade before the original failed, and the fact that the replacement failed within a few hours of being put into in service, lead me here.
Best is to replace all electrolytic caps in this device. Use higher rated ones. I used to repair these useless devices but thankfully forgot a lot 😉
Beware of the X-Pre as it is even worse.
This series suffers from design imperfections like too low power supply voltages, overheating and mediocre part quality. No chain will improve from inserting a weak element.
Beware of the X-Pre as it is even worse.
This series suffers from design imperfections like too low power supply voltages, overheating and mediocre part quality. No chain will improve from inserting a weak element.
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