Recapping and FM tuner station issue on Technics SA-5360 Stereo FM/AM tuner amplifier

Thread Starter

Rahulk70

Joined Dec 16, 2016
536
Hello everyone,

I had recently purchased a Technics SA-5360 Stereo amp tuner from eBay. This was after a long break since 2019 I took from my vintage electronics hobby. I used to mainly collect and restore tube based tuners and amps, but recently it has become quite expensive I noticed, especially the replacement tubes. I've an EL84, 6L6GC & 6V6 based amps, but to preserve it's life and also gotta say the beautiful design of these vintage stereo sets got my attention. The tuner sounds really great when I tried on aux with a pair of Sony speakers (for testing only). Phono I'm yet to test. AM seems to be fine, but on FM it seems to detect on certain stations (maybe two or three) and they are quite clear with stereo. But between those channels when turning the tuning knob it's dead silence, I tried with my Pilot tube tuner and definitely there are a lot more other FM channels. What could be the potential issue here? BTW I had attached a long antenna wire from my tube tuner, but made no difference apart from the quality of the detected ones.

Another issue is the volume knob, though I sprayed some CRC contact cleaner the volume a lot of times is very low and if I give the knob a mild push or back and forth movement the volume goes to correct level. I assume I may have to replace the dual gang potentiometer.

Finally, is it necessary to re-cap the capacitors in the stereo amplifiers. Now in old tube based tuners the first thing I used to change was the electrolytic caps, then the film caps and some resistors since they are very old and probably from the late 40s-50s. But since these Japanese ones are much more recent is it still necessary?

Thanks,
Rahul
 

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seanstevens

Joined Sep 22, 2009
256
Hi, regarding the FM quietness/silence between stations, and good stereo signal on other stations, that may have to do with some of the IF coils may be detuned. I used to mess around with FM/AM radios 40-odd years ago as a kid and found some of the IF coils if they were detuned, the FM hiss would disappear in between stations.

I never figured out why at the time, but I can only guess that it may be the discriminator or such coil, they come in different colours (functions). I would use a plastic tool so as not to detune/break any of them, turn the screws one at a time to see the effect and they do interact with each other.
 

Tonyr1084

Joined Sep 24, 2015
7,943
Hi, regarding the FM quietness/silence between stations, and good stereo signal on other stations, that may have to do with some of the IF coils may be detuned. I used to mess around with FM/AM radios 40-odd years ago as a kid and found some of the IF coils if they were detuned, the FM hiss would disappear in between stations.

I never figured out why at the time, but I can only guess that it may be the discriminator or such coil, they come in different colours (functions). I would use a plastic tool so as not to detune/break any of them, turn the screws one at a time to see the effect and they do interact with each other.
Foolishly I messed with some of the tuning coils as well in an old Panasonic. I broke one of the coils (ferrite material) using a regular screw driver - and it interfered with the tuning while the metal screwdriver was present; and I managed to screw up the whole thing. IF you change the position of a coil, first - don't break it like I did mine, second - mark its exact orientation so you can return it to that position in the future if somehow you manage to make a mess of it like I did with mine. Keep careful notes of which coils you adjusted and how much you adjusted them and which way you turned the adjustments. Otherwise - unless you have the necessary equipment to realign the receiver - follow the advice I failed to follow.
 

Thread Starter

Rahulk70

Joined Dec 16, 2016
536
I can see that there are some markings on the IF coils showing the current position, but prior to messing with them I'll see what the manual says. Also, something I'll look into first is if the Mono & FM muting buttons are working properly. Something which I noticed just now.
 

Ylli

Joined Nov 13, 2015
1,089
From the symptoms, my first guess is that the input dual-gate MOSFET is bad. Those are very susceptible to damage from nearby electrostatic discharges (lightning).
 

LadySpark

Joined Feb 7, 2024
170
AM seems to be fine, but on FM it seems to detect on certain stations (maybe two or three) and they are quite clear with stereo. But between those channels when turning the tuning knob it's dead silence, I tried with my Pilot tube tuner and definitely there are a lot more other FM channels. What could be the potential issue here?
Nothing unless FM muting button is not pushed in that mutes the signal when off channel.
 

MisterBill2

Joined Jan 23, 2018
18,934
The very first thing to check with the FM portion is the interstation muting adjustment. That is not part of the alignment and can certainly cause only the very strongest stations to be heard. THEN verify the antenna connections. Some receivers are almost deaf with out an adequate antenna. DO NOT attempt alignment unless you have the right equipment and fully understand what you are doing!!
 
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