Hello,
I own a Cambridge Audio 851c CD-player/DAC/Pre-amp which I am currenty using av a DAC/Pre-amp.
Lately it has started acting up: WHen powering it on it will produce loud, static white noise. Usually switching it off and on a couple of times removes this problem, and it works as expected after this. However, as this i quite annoying, I decided to open it and have a look inside as the unit is out of warranty.
I inspected the insides and found what appears to be bad capacitors on the power board, which again is connected to the toroidal transformer. The DAC/pre-section looked fine.
I've attached some pictures of the power-board.
Could this be the cause of the problem described?
Could swapping the capacitors be a simple repair?
If so, does Cambridge Audio use "standard" soldering lead, or is there something which I should be aware of?
The values of the caps that seem bad are as follows:
C3 - 15 uF 450V, labeled 1921TQ
C14 - 1500uF 16V, labeled 92GW
C2 - 1000uF 16V, 10IICH
If this might be a matter of simply swapping the caps are there any recommended brands/types of caps or will any do?
I appreciate all and any input, thank you.
I own a Cambridge Audio 851c CD-player/DAC/Pre-amp which I am currenty using av a DAC/Pre-amp.
Lately it has started acting up: WHen powering it on it will produce loud, static white noise. Usually switching it off and on a couple of times removes this problem, and it works as expected after this. However, as this i quite annoying, I decided to open it and have a look inside as the unit is out of warranty.
I inspected the insides and found what appears to be bad capacitors on the power board, which again is connected to the toroidal transformer. The DAC/pre-section looked fine.
I've attached some pictures of the power-board.
Could this be the cause of the problem described?
Could swapping the capacitors be a simple repair?
If so, does Cambridge Audio use "standard" soldering lead, or is there something which I should be aware of?
The values of the caps that seem bad are as follows:
C3 - 15 uF 450V, labeled 1921TQ
C14 - 1500uF 16V, labeled 92GW
C2 - 1000uF 16V, 10IICH
If this might be a matter of simply swapping the caps are there any recommended brands/types of caps or will any do?
I appreciate all and any input, thank you.
Attachments
That could be some kind of glue you are seeing and used to add mechanical support to the tall caps... its often seen in commercial gear.
I assume you mean the noise in on the audio feed and not actual physical noise from the SMPS... if so then you may be looking at a different issue.
Recapping is an easy job on something like that, and often its the small caps that give problems just as often as the large. Always change ALL electrolytics. Look for parts rated at 105C and always check physical sizes before ordering. Go for big brand names such as Panasonic or Rubycon.
Use normal solder would be my advice, no matter what was used in production.
I assume you mean the noise in on the audio feed and not actual physical noise from the SMPS... if so then you may be looking at a different issue.
Recapping is an easy job on something like that, and often its the small caps that give problems just as often as the large. Always change ALL electrolytics. Look for parts rated at 105C and always check physical sizes before ordering. Go for big brand names such as Panasonic or Rubycon.
Use normal solder would be my advice, no matter what was used in production.
Hi,
I've the same problem on my 851C. For a long time, it works as you said and problems disappear after switching on/off, but now the problem is more or less constant!
Did you find a solution?
Thanks for you reply!
I've the same problem on my 851C. For a long time, it works as you said and problems disappear after switching on/off, but now the problem is more or less constant!
Did you find a solution?
Thanks for you reply!
I changed 2 surface mount capacitors C227 and C229 on the left hand side of the main board. I cant remember what value the capacitors were, from memory I tested their value with a capacitance meter. You will also have to do the other channel if the static is in both channels.
Same problem here. Additional symptom was kind of "short circuit" after noise get stronger. Then house fuse was off. It didn't happen very often.
I can confirm that switching off and on was helping on begining but now "... is more or less constant!...".
I can confirm that switching off and on was helping on begining but now "... is more or less constant!...".
