Hi all I've been given a Fender bassman to repair. So far I've found one of the 470 ohm resistors from the supply to the power tubes(pin 4) to be blown apart and the remaining three to be way over tolerance (over 200 ohms in one case). Obviously my first job is to replace these, however when I checked the output transformer I found the primarys to be only about 40 ohms to the centre tap (80 ish total), when I'm sure it should be closer to about 4kohm. My initial reaction was that it is blown, but I'm confused due to the equal balance of each side relative to the centre tap. Am I doing something wrong in the way I'm measuring the primary coils? I've tried this using two different digital multimeters set to read ohms and got the same result twice. I would be very pleased (as would its owner) if its only the resistors that need replacement but I dont want to risk the amp any further damage by switching it on if the o/p transformer is at fault.
Sorry for my ramblings but any help is much appreciated.
Cheers Just