I bought a Rotel RA970Bx in non-working condition.
Inspired by this upgrade project:
https://audiokarma.org/forums/index...storation-upgrade-of-a-rotel-ra-970bx.732725/
It turned on, but had no audio output to either channel, had blown fuses, bubbling filter caps and out of spec Resistors (R645 and R646 in the service manual).
No transistor short circuits or loose solder joints.
Figure if I need to replace some caps and some resistors, I might as well upgrade a bunch.
Leestereo's upgrade includes WIMA stacked film caps replacing the small electrolytics (2.2uf 63V film replacing 10uf 50V electrolytic), replacing / moderately upgrading larger electrolytics, upgrading the Op-amp, upgrading Zener diodes to lower tolerance, replacing resistors which are caught up in board glue. Check it out.
I'm holding off on the glue kissed bits and the Op-amp for now.
Replacing filter caps with Nichicon LKS 12000uf 63V, stock are 10000uf 50V Rotel caps.
---
One of my concerns was that 2.2uf film replacing 10uf electrolytics is a significant reduction in total capacitacitance in the signal path.
The 3.3uf WIMA film caps are not significantly more expensive than the 2.2's and are exactly the same size as the 2.2's. I raised the 3.3's as a suggestion on the thread and was gunned down saying that it would affect the output tone and that it is not recommended.
My questions:
- is the reduction in capacitance from electrolytic to film caps ok?
-Do film caps have some magic that electrolytics do not that alow a lower capacitance spec to perform similarly?
- Would larger film caps, of the same manufacturer and product line, in the signal path change the tone?
- Any comments / critique?
Inspired by this upgrade project:
https://audiokarma.org/forums/index...storation-upgrade-of-a-rotel-ra-970bx.732725/
It turned on, but had no audio output to either channel, had blown fuses, bubbling filter caps and out of spec Resistors (R645 and R646 in the service manual).
No transistor short circuits or loose solder joints.
Figure if I need to replace some caps and some resistors, I might as well upgrade a bunch.
Leestereo's upgrade includes WIMA stacked film caps replacing the small electrolytics (2.2uf 63V film replacing 10uf 50V electrolytic), replacing / moderately upgrading larger electrolytics, upgrading the Op-amp, upgrading Zener diodes to lower tolerance, replacing resistors which are caught up in board glue. Check it out.
I'm holding off on the glue kissed bits and the Op-amp for now.
Replacing filter caps with Nichicon LKS 12000uf 63V, stock are 10000uf 50V Rotel caps.
---
One of my concerns was that 2.2uf film replacing 10uf electrolytics is a significant reduction in total capacitacitance in the signal path.
The 3.3uf WIMA film caps are not significantly more expensive than the 2.2's and are exactly the same size as the 2.2's. I raised the 3.3's as a suggestion on the thread and was gunned down saying that it would affect the output tone and that it is not recommended.
My questions:
- is the reduction in capacitance from electrolytic to film caps ok?
-Do film caps have some magic that electrolytics do not that alow a lower capacitance spec to perform similarly?
- Would larger film caps, of the same manufacturer and product line, in the signal path change the tone?
- Any comments / critique?
