Here is a follow-up from yesterday. Including Pictures. While there are various differences in the front ends, many are similar and easy to follow using these directions. I am also going to give you the basics for "Analog" Tuners. The adjustment for tuners without the large tuning capacitor and pulley are totally different.
And only do these adjustment with units that have at least a working tuning meter, and preferrably units that also have a center tune meter or indicator, and use a pair of headphones to listen during the tuning process.
1) The FM adjustments that you should do are the ones in line with the tuning capacitor plates that have a wider spread. The sections with the closer spaced, and more plates are the AM section, which have their own adjustments.
2) Adjustments need to be made with the right alignment tool. Do not use a metal tool for the screw (Capacitor) adjustments, and do not use a metal allen wrench for the coil adjustments.
3) The more high end the receiver, the more likely you will find 4 sections for FM alignment. Lower end receivers usually have 3. If it has only three, then you need to adjust starting on the side with the shaft and pully. This is the Ant section. The next section (Middle) is the RF section, and the least section (Farthest from the pulley) is the Oscillator section which when adjusting allows you to "move" the station to the left or right
4) The trimmer Capacitor for adjusting the station to match the dial indicator, is usually found on top furthest away from the pully. This adjustment you will find is a different design than the plain screws on a piece of spring metal that the other are, as a point of reference. You will notice that the screw is smaller, and needs a fairly thin blade to adjust it. At times, in certain units, you will notice that there isn't any adjustmet on top of the tuning capacitor, for the last section of widely spaced capacitor plates. These units will almost always have these adjustable trimmer caps located on the circuit board very close the that last section on the tuning capacitor. They may also have the low end oscillator adjustment located right next to the cap
As mentioned previous, here are pictures of the FM Front end, as well as the points to lube the Tuning cap bearings if you are getting noise when turning the dial. Do the lubrication with the unit unplugged. Be very careful to not get any of the lube on the tuning plates themselves, or drip down to the board below. Just apply a very small amount to wet where the contact is and then turn from low end to high end to distribute the lube. On this example you can see marking stamped on the metal. TCA is Tuning Cap Antenna, TCR is Tuning Cap "RF", TCO is Tuning Cap Oscillator. LA is the Antenna Coil Adjustment, LR is the RF Coil adjustment, LO is the Oscillator coil adjustment..There is also another Adjustable transformer relating to the FM front end called IF. I don't recommend touching this if you don't have a distortion analyzer to look for distortion. Your ears may not pick out the distortion.
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Now for the High End Tuning.
Power on the unit, keep it on FM stereo, and leave the FM muting on if possible. Make sure you have at least a FM dipole antenna connected to the 300 terminals on the back. Tune to a high medium strength station around 106FM. Dont use a station that is showing a strength of 5 on a scale of 5. Check if the station identifier broadcast matches to the tuning dial indicator. It it is right on or very close, I wouldn't even mess with the "Oscillator adjustments".
1) using your alignment tool start first by adjusting TCA screw adjustment until you find the peak signal strength (you probably need to go CW and then CCw to find the best spot.
2) go to the next adjustment TCR and adjust the same was as you did the Antenna screw adjustment.
3) go to the second TCR adjustment if the unit you are working on has 4 FM sections. Adjust the screw cap adjustment the same way as the others.
4) adjust the Oscillator screw adjustment only if the dial indicator is off noticably with the station playing. In reality, many time when this difference is found, it is more likely that the dial cord is stretched causing the inconsistancy. But trying to adjust dial cords can be a pain in the neck, and you always have the chance of breaking the cord and having to redo the whole cord, so I usually adjust the oscillator rather than trying to adjust the cord, or the dial indicator on the cord.
NOTE: If the unit has a center Tune meter, note that this may not be in dead center when you have peaked the signal meter. Not to worry. Make sure you tune for the signal meter, and that the station stays on, doesn't mute, and that the stereo indicator stays on.
Pictures of high end adjustments in order.
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Now for the Low End Tuning.
Power on the unit, keep it on FM stereo, and leave the FM muting on if possible. Make sure you have at least a FM dipole antenna connected to the 300 terminals on the back. Tune to a high medium strength station around 92 FM. Dont use a station that is showing a strength of 5 on a scale of 5. Check if the station identifier broadcast matches to the tuning dial indicator. It it is right on or very close, I wouldn't even mess with the "Oscillator adjustments".
1) using your Hex Coil alignment tool start first by adjusting LA screw adjustment until you find the peak signal strength (you probably need to go CW and then CCw to find the best spot.
2) go to the next adjustment LR and adjust the same was as you did the Antenna Hex Coil adjustment.
3) go to the second LR adjustment if the unit you are working on has 4 FM sections. Adjust the Hex Coil adjustment the same way as the others.
4) adjust the Oscillator Hex Coil adjustment only if the dial indicator is off noticably with the station playing. In reality, many time when this difference is found, it is more likely that the dial cord is stretched causing the inconsistancy. But trying to adjust dial cords can be a pain in the neck, and you always have the chance of breaking the cord and having to redo the whole cord, so I usually adjust the oscillator rather than trying to adjust the cord, or the dial indicator on the cord.
NOTE: If the unit has a center Tune meter, note that this may not be in dead center when you have peaked the signal meter. Not to worry. Make sure you tune for the signal meter, and that the station stays on, doesn't mute, and that the stereo indicator stays on.
Pictures of low end adjustments to follow in next update .