Hi, this is for now last post on this amp.
It is not so relevant, it is about main PS, while I had this opened I wanted to see how PS works in max currents, if anyone is interested:
I opened connection between one bridge rectifier and capacitor filter, 0R1 1% resistor was inserted in series so I can measure microvolts that translate in PS currents, my multi-meter has 1ms and 100ms peak and hold , so I used only this, not scope. This is how it looks:
1. Inserted additional chokes (all very high current rated) in series making effectively L-C filters:
a. With "small" choke; filtered voltage remained pretty much the same; 30V. Continuous average current little bit decreased and 1ms peaks (ripple) went just a bit down (8.16A comparing to 8.5A) .
b. With "large" choke; filtered voltage dropped significantly to 21.6V, 1ms ripple peaks also reduced a lot to 4.6A.
2. Without any choke, PS as is; bridge rectifier followed by 100,000 microF capacitors:
a. Continuous DC current: 2.44 A (corresponds close enough with 1.12 A I measured per +- leg earlier in post #5
b. 1ms peaks (ripple) 8.5 A
c. Switch on (switch on mains with empty capacitors) 1ms peak 70 A, with 100ms peak its averaged 19A
New F&T specification for GM series 100,000 microF /40V capacitors (mine are much older and little bit bigger than new products) declares:
So seems all its fine without additional chokes.
(PS these huge electrolytic have generous film and close to load decoupler small capacitor helpers)
For now, that's it from me on this subject, I'm closing the amp and releasing workbench,
Cheers,
Drazen
It is not so relevant, it is about main PS, while I had this opened I wanted to see how PS works in max currents, if anyone is interested:
I opened connection between one bridge rectifier and capacitor filter, 0R1 1% resistor was inserted in series so I can measure microvolts that translate in PS currents, my multi-meter has 1ms and 100ms peak and hold , so I used only this, not scope. This is how it looks:
1. Inserted additional chokes (all very high current rated) in series making effectively L-C filters:
a. With "small" choke; filtered voltage remained pretty much the same; 30V. Continuous average current little bit decreased and 1ms peaks (ripple) went just a bit down (8.16A comparing to 8.5A) .
b. With "large" choke; filtered voltage dropped significantly to 21.6V, 1ms ripple peaks also reduced a lot to 4.6A.
2. Without any choke, PS as is; bridge rectifier followed by 100,000 microF capacitors:
a. Continuous DC current: 2.44 A (corresponds close enough with 1.12 A I measured per +- leg earlier in post #5
b. 1ms peaks (ripple) 8.5 A
c. Switch on (switch on mains with empty capacitors) 1ms peak 70 A, with 100ms peak its averaged 19A
New F&T specification for GM series 100,000 microF /40V capacitors (mine are much older and little bit bigger than new products) declares:
- Ripple current 18.3A
- ESR 4mOhm
So seems all its fine without additional chokes.
(PS these huge electrolytic have generous film and close to load decoupler small capacitor helpers)
For now, that's it from me on this subject, I'm closing the amp and releasing workbench,
Cheers,
Drazen
