mpr2000
Active Member
I am working on a 3000a that is all original and has one shorted output. This one does not have the service bulletin applied for the speaker protection.
Aside from recapping and replacing OOT components, I'll be doing the following:
(1) Replace driver board diodes with 1N4002 diodes
(2) Replace all four output transistors with 2N3772G transistors
(3) Change emitter resistors from .3 ohms to 1 ohm
(4) Add base series resistors per the service bulletin
(5) Change DC fuses from 4 amp to 3 amp
And finally - my question:
Instead of adding the two 1000uf caps per the service bulletin (output protection mod), what do you folks think of using one of those speaker protection board kits?
Pros:
- Reports of minor performance degradation by adding the 1000uf caps eliminated
- Modern method to monitor for DC on speaker outputs
- Cheap
Cons:
- Not original
- Need to engineer a non-obtrusive way to provide power to the added speaker protection board
Thoughts?
Aside from recapping and replacing OOT components, I'll be doing the following:
(1) Replace driver board diodes with 1N4002 diodes
(2) Replace all four output transistors with 2N3772G transistors
(3) Change emitter resistors from .3 ohms to 1 ohm
(4) Add base series resistors per the service bulletin
(5) Change DC fuses from 4 amp to 3 amp
And finally - my question:
Instead of adding the two 1000uf caps per the service bulletin (output protection mod), what do you folks think of using one of those speaker protection board kits?
Pros:
- Reports of minor performance degradation by adding the 1000uf caps eliminated
- Modern method to monitor for DC on speaker outputs
- Cheap
Cons:
- Not original
- Need to engineer a non-obtrusive way to provide power to the added speaker protection board
Thoughts?