05-22-2018, 08:16 PM
I'm working on a Sherwood S8900A that I bought cheap in the 1980's. It was cheap because the FM hardly worked. Lots of static when tuning, unreliable stereo when I did get a station dialed in. That was ok at the time since all I wanted was the amplifier for use at the office. I haven't used it in years. This thread caused me to dig it out of the equipment archives to see what I could do with it. The bass control is missing. I think I remember something falling on it and physically breaking the control so I bypassed it with fixed resistors at a most used bass level. I obviously must have changed one of the filter caps at one point though I don't remember doing it.
The static occurred when the tuning dial was turned so I suspected a bad ground or cross plate contamination. A solid blast of contact cleaner cleaned up the tuning cap and the static was gone and has worked great since. I found the alignment WAY off so i suspect someone tried to correct the problems by twisting slugs, gave up and traded it in. That's when I bought it. It is now working great with excellent sensitivity, great stereo and good sound. I've ordered caps to replace the filter caps (I will re-stuff them) and e-caps for the rest of the circuitry, just to be proactive. But I need help!
I cannot get the dial to track properly. Using the slug in the oscillator coil, I can zero in on the low end of the dial. Using the cap, I can set the high end. So, the two frequencies I use the most are dead on at 88.5 and 106.9. The middle of the dial is about 500KHz off. For 100.5, I have to tune to 100. It bugs me and no matter how much I diddle with the coil and trimmer, I cannot improve it. Does anyone have suggestions? Or, is there an instructional paper or video out there that I have not been able to find? Thanks for any help you give!
The static occurred when the tuning dial was turned so I suspected a bad ground or cross plate contamination. A solid blast of contact cleaner cleaned up the tuning cap and the static was gone and has worked great since. I found the alignment WAY off so i suspect someone tried to correct the problems by twisting slugs, gave up and traded it in. That's when I bought it. It is now working great with excellent sensitivity, great stereo and good sound. I've ordered caps to replace the filter caps (I will re-stuff them) and e-caps for the rest of the circuitry, just to be proactive. But I need help!
I cannot get the dial to track properly. Using the slug in the oscillator coil, I can zero in on the low end of the dial. Using the cap, I can set the high end. So, the two frequencies I use the most are dead on at 88.5 and 106.9. The middle of the dial is about 500KHz off. For 100.5, I have to tune to 100. It bugs me and no matter how much I diddle with the coil and trimmer, I cannot improve it. Does anyone have suggestions? Or, is there an instructional paper or video out there that I have not been able to find? Thanks for any help you give!
