11-15-2013, 09:43 AM
Back at this beastie this evening. Found the AM problem. It was one section of one of those pretty chrome three section caps. Dead short... pulled the regulated B+ right down to nothing, and didn't smoke the 1K resistor in series with that cap. I replaced the entire can with a terminal strip and three 0.1/630 caps and a 1K resistor. AM/SW are back, and better than ever.
FM is improved a little from before, I can now receive most of the stations on my inhouse cable system, but tuning is still very scratchy, especially on the lower end of the band. Still trying to figure that one out. Only thing I can think of is poor ground connection to the tuner rotor.
Another issue with the FM that I need to figure out is why the 1st IF secondary (which is on the amp chassis) does not tune properly. I have to tune the slug as far in as it will go to get anywhere near the peak. Guess I'll have to pull the can off and see if perhaps something has happened to the coil.
Tomorrow, it's go through and change out all those nice can caps. Wish I could restuff them, but I just have no way of desoldering the bottoms.
FM is improved a little from before, I can now receive most of the stations on my inhouse cable system, but tuning is still very scratchy, especially on the lower end of the band. Still trying to figure that one out. Only thing I can think of is poor ground connection to the tuner rotor.
Another issue with the FM that I need to figure out is why the 1st IF secondary (which is on the amp chassis) does not tune properly. I have to tune the slug as far in as it will go to get anywhere near the peak. Guess I'll have to pull the can off and see if perhaps something has happened to the coil.
Tomorrow, it's go through and change out all those nice can caps. Wish I could restuff them, but I just have no way of desoldering the bottoms.
