Hi everyone,
I was messing around a bit on my Cambridge 851N Streamer/DAC and thought of swapping the final opamps (BB OPA2134 SMD) with discrete ones.
After removing the 2 original opamps and soldering the new ones I noticed random noise mixed with the audio on one channel (right channel). I though that maybe the new opamps were oscilation or just not good for the purpose, etc, and dessoldered them and placed the old ones again.
Now, random noise on both channels, higher on right channel. This is on both RCA and XLR oupput as the opamps feeds both.
So, again, these are smd's and soldering and dessoldering these can be tricky and I think I may have applied heat for longer than I should.
The +15V and -15V for the opamps are OK. The traces are also good. I measured the audio ouyput and I read negative DC voltage on both channels. the voltage goes up and down. Is around -2v on the left channel but on the right channel goes up to -15v sometimes.
I asking for some help on which component can maybe be damaged due to overheathing. Maybe the small 47p capacitors aroud the -15V rail close to the opamp?
I'm adding some files. Also have the full schematic.
Any help would be greatly apreciated!
Againg, everything works well, except for the noise caused by the negative DC.
Thanks
Andre
I was messing around a bit on my Cambridge 851N Streamer/DAC and thought of swapping the final opamps (BB OPA2134 SMD) with discrete ones.
After removing the 2 original opamps and soldering the new ones I noticed random noise mixed with the audio on one channel (right channel). I though that maybe the new opamps were oscilation or just not good for the purpose, etc, and dessoldered them and placed the old ones again.
Now, random noise on both channels, higher on right channel. This is on both RCA and XLR oupput as the opamps feeds both.
So, again, these are smd's and soldering and dessoldering these can be tricky and I think I may have applied heat for longer than I should.
The +15V and -15V for the opamps are OK. The traces are also good. I measured the audio ouyput and I read negative DC voltage on both channels. the voltage goes up and down. Is around -2v on the left channel but on the right channel goes up to -15v sometimes.
I asking for some help on which component can maybe be damaged due to overheathing. Maybe the small 47p capacitors aroud the -15V rail close to the opamp?
I'm adding some files. Also have the full schematic.
Any help would be greatly apreciated!
Againg, everything works well, except for the noise caused by the negative DC.
Thanks
Andre
Attachments
A voltage regulator may have died.
Check the power rails.
Opa2134 is very good, a discreet op amp is not likely to equal its performance.
What voltage is on R196, R197?
Check the power rails.
Opa2134 is very good, a discreet op amp is not likely to equal its performance.
What voltage is on R196, R197?
Last edited:
Thank you!
Will check those. But on both opamps U71 and U75 I have perfect +15v and -15v on pins 4 and 8.
Here are is some more infomation that may help.
https://79hfjm.s.cld.pt (analogue stage schematic)
https://yo4ftp.s.cld.pt (analogue stage power supplies)
Will check those. But on both opamps U71 and U75 I have perfect +15v and -15v on pins 4 and 8.
Here are is some more infomation that may help.
https://79hfjm.s.cld.pt (analogue stage schematic)
https://yo4ftp.s.cld.pt (analogue stage power supplies)
Attachments
Last edited:
It might help if you told us which opamps you put in ...
Or we just continue to speculate what happened till kingdom come.
Jan
Or we just continue to speculate what happened till kingdom come.
Jan
Clearly they are not fully compatible. They cause a problem the other one didn't.
Unless you made a mistake somewhere..
Jan
Unless you made a mistake somewhere..
Jan
