Model FM-61 Automatic brand fm converter.
Posts: 135
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Joined: Mar 2016
City: Idaho Falls, Idaho
I've finally had time to come back to this unit and was able to fix a couple things. One I installed a new output antenna that helped quite a bit with the fading problem. Adding a main antenna helped as well. I had to re string as well as the old one snapped on me. As for the first problem I'm not sure how to fix that. I did figure out that my stations on the high end of the scale are at the bottom end of the scale but my final high station starts about where it should and but goes to the end of the scale. Now with the rest of the high scale side stations being at the bottom is this still a problem with the FM RF Amp. - FM Conv. tube or an alignment problem?
Posts: 135
Threads: 14
Joined: Mar 2016
City: Idaho Falls, Idaho
Update: so I found and replaced the ECC86 tube with one that is brand new in the box testing 950/1000 and there was no change. Same problem, high stations were still at the bottom of the scale with the last station at the top being 103.3.
Posts: 7,285
Threads: 268
Joined: Dec 2009
City: Roslyn Pa
Ok goto pg 6 of the sam's and locate A8. This adjustment is used to set the high end of the band at 108mc. Making this adjustment will move the stations so pick a local station near 108mc and adjust till you can place the station on the proper location on the dial.
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
Terry
Posts: 135
Threads: 14
Joined: Mar 2016
City: Idaho Falls, Idaho
So I'm finally getting back to this one after some distractions and I have made some improvements but not 100% there yet. So I moved the A8 a little and it didn't do anything, so I set it back and found that the A9 moved the scale up and down. So I now have my scale set in the right spot and in the process some of my stations have come back at the top as well. My final local station is now at 105.5, almost getting the next one at 106.3. A quarter turn either direction does nothing, do I keep going until it changes?
Posts: 7,285
Threads: 268
Joined: Dec 2009
City: Roslyn Pa
A8 isn't going to move the stations, it effects the sensitivity. A9 will move the stations. Since you don't have the proper generator to align it use A9 to move the highest in frequency fm station in your area to it's proper place on the dial. I suppose you could run out of adjustment. Don't adjust the 10.7 IF transformers.
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
Terry
Posts: 135
Threads: 14
Joined: Mar 2016
City: Idaho Falls, Idaho
I think I may have it, I had to turn the screw about 1/8 more and they're all on, I just need to slide my indicator about 3/8 to the left and everything should line up. I probably still need to change the electrolytic capacitors in this for it to be completely reliable. I couldn't find the exact value for this unit, it calls for 400mfd @ 15 volts, best I could get was 470mfd at 25 volts, will that be okay?
Posts: 667
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City: Bellmawr, NJ
a little over on thee mfd and volts is NOT a Bad thing,,,,,NEVER under,,,,CHEERS
Posts: 7,285
Threads: 268
Joined: Dec 2009
City: Roslyn Pa
(01-02-2017, 02:39 PM)flatheadjr Wrote: I think I may have it, I had to turn the screw about 1/8 more and they're all on, I just need to slide my indicator about 3/8 to the left and everything should line up. I probably still need to change the electrolytic capacitors in this for it to be completely reliable. I couldn't find the exact value for this unit, it calls for 400mfd @ 15 volts, best I could get was 470mfd at 25 volts, will that be okay?
Yup you fine.
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
Terry
Posts: 1,114
Threads: 14
Joined: Feb 2013
City: Irvington, NY
I would not worry too much about changing the electrolytic.
That cap is just a filter for the +12V to eliminate alternator noise. It otherwise does not affect the operation of the tuner and its a low voltage sealed metal can type which is quite reliable.
Posts: 135
Threads: 14
Joined: Mar 2016
City: Idaho Falls, Idaho
Any way to check that capacitor to make sure it's in good shape?
Posts: 1,114
Threads: 14
Joined: Feb 2013
City: Irvington, NY
If it were mine I would connect it up in my car and see how it operates. If you here whine from the alternator on the radio when you accelerate the engine then the cap might need replacement. If you hear the alternator noise, you can jump the replacement caps across the existing terminals and see if it makes any difference
Otherwise you could disconnect all the wires and components from the cap terminals and check with a capacitance and ESR meter, but I would not bother as it would be just about as much work as installing new caps. Unless you remove and restuff the existing capacitor can with new electrolytics, you will have to install terminal strips to mount the new caps and the existing components connected to them.
That electrolytic has only 12 VDC across it and the chances for failure are minimal. Again, the only purpose for the cap is to filter the alternator noise so if you don't hear it then it is fine as is.
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