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1990 Fender Bassman re-issue combo. model 5F6-A
I tested 3 filter caps (after draining them) in circuit and found the ESR readings to be 3.5, 3.5 and 7.5. They are 22/500v caps. According to my meter, these values indicate a bad cap.
Question: How reliable is an ESR meter? These caps are not super old.
The trouble is, oscillating and distortion kicks in at half volume on the normal inputs. I'm going to check the plate load resistors as well...may be fried or starting to go.
I checked the bias and all the tubes seem fine.
Any pointers on flipping this board as this is the first reissue bassman I've had to take apart. Looks like I can leave the chassis in and just pull some connectors, remove the jacks and pots and unscrew the board.
I tested 3 filter caps (after draining them) in circuit and found the ESR readings to be 3.5, 3.5 and 7.5. They are 22/500v caps. According to my meter, these values indicate a bad cap.
Question: How reliable is an ESR meter? These caps are not super old.
The trouble is, oscillating and distortion kicks in at half volume on the normal inputs. I'm going to check the plate load resistors as well...may be fried or starting to go.
I checked the bias and all the tubes seem fine.
Any pointers on flipping this board as this is the first reissue bassman I've had to take apart. Looks like I can leave the chassis in and just pull some connectors, remove the jacks and pots and unscrew the board.