Hello, I have got this Fisher AM/FM Stereo Synthesizer tuner from around 1980 for many years now. At some point long ago it started to produce audible distortion with all Stereo stations, independent of signal strength. It works fine if switched to Mono mode and all functions are OK, like auto tuning, store, mute and LED's. Because of the slow increase in distortion over time I think it must be a (typical?) component loosing or changeing its value. I noticed an identical problem on other vintage tuners too.
The stereo containing frequency seems to be one or two digits away from the maximum strength frequency. Like I get a stereo light at 91.00 and maximum undistorted Mono at 90.20
Does anyone have an idea what to look for? I have found no service manual, so I did not open it yet. I dislike turning anything inside without a plan. I got a scope and all the usual stuff for electronics, but I'm kind of fixed on amps, my knowledge of tuners is very near to zero. Next I would mark the positions of the adjustable coils and watch for any change turning them a little, but that will be a last try before disposing it.
Would be great to get some hint what to look for and a pointer to a service manual.
Thank you.
The stereo containing frequency seems to be one or two digits away from the maximum strength frequency. Like I get a stereo light at 91.00 and maximum undistorted Mono at 90.20
Does anyone have an idea what to look for? I have found no service manual, so I did not open it yet. I dislike turning anything inside without a plan. I got a scope and all the usual stuff for electronics, but I'm kind of fixed on amps, my knowledge of tuners is very near to zero. Next I would mark the positions of the adjustable coils and watch for any change turning them a little, but that will be a last try before disposing it.
Would be great to get some hint what to look for and a pointer to a service manual.
Thank you.
Well, you have to open it eventually. Even without service manual it should be easy to see what stereodecoder chip is used.
Most of the time schematics of stereodecoder is close to chips recommended circuit.
Most of the time schematics of stereodecoder is close to chips recommended circuit.
Ok, now I got at least an idea how to start. Thank you adason.
Growing older I decided to ask someone who could know before doing a blind flight. In my youth no one would give a honest answer, to protect the little they knew. So I had to figure it out by my self. This has changed with the internet. So at least it is not all just lies and trouble making on the net...
Growing older I decided to ask someone who could know before doing a blind flight. In my youth no one would give a honest answer, to protect the little they knew. So I had to figure it out by my self. This has changed with the internet. So at least it is not all just lies and trouble making on the net...
Replace all the small caps on the stereo MPX chip. The 10.7Mhz coil may be mistuned as well.
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I have no idea what the tuner chip may look like.
For tools, I got a 20MHz scope (Hitachi) and a solid 1MHz function generator.
I repair and build amps, but never touched annything that is supposed to oscillate.
I'm completely lost with tuner, FM and TV stuff.
So far I could get the signal back on the center of the supposed frequency, which was about 0.15 off to one side and make stereo switch on again at that setting. I had to trim two coils for that. I know this is not the requiered "real" fix, because coild don't turn by them selves, but for a limited time in the workshop it is OK. Also I don't know how "good" this tuner should sound anyway, I'm quite sensitive to distortion. 0.5% may be more than I like depending on order.
During this process I decided not to do any more, because FM analog broadcast is to be ending soon and I still have an ONKYO Integra tuner with memory loss, that plays in another sound league anyway. It needs a new gold cap and I have a complete service manual. So sorry Fisher, the Integra wins big this time.
Thank you all for your help, I deeply appreciate it.
For tools, I got a 20MHz scope (Hitachi) and a solid 1MHz function generator.
I repair and build amps, but never touched annything that is supposed to oscillate.
I'm completely lost with tuner, FM and TV stuff.
So far I could get the signal back on the center of the supposed frequency, which was about 0.15 off to one side and make stereo switch on again at that setting. I had to trim two coils for that. I know this is not the requiered "real" fix, because coild don't turn by them selves, but for a limited time in the workshop it is OK. Also I don't know how "good" this tuner should sound anyway, I'm quite sensitive to distortion. 0.5% may be more than I like depending on order.
During this process I decided not to do any more, because FM analog broadcast is to be ending soon and I still have an ONKYO Integra tuner with memory loss, that plays in another sound league anyway. It needs a new gold cap and I have a complete service manual. So sorry Fisher, the Integra wins big this time.
Thank you all for your help, I deeply appreciate it.
The oscillator test point is at pin 12 of the MPX IC106, an LA-3350.
Coils don’t turn by themselves, but the components they are tuned to change their impedances, including both valves and transistors, let alone mere capacitors, and this is the real reason why realignment is required.
Coils don’t turn by themselves, but the components they are tuned to change their impedances, including both valves and transistors, let alone mere capacitors, and this is the real reason why realignment is required.
Exactly this is what I wanted to point out, there are for sure other components that are aged near to defective now. While at it I just decided that changing all these parts and the needed tools to calibrate anything afterwards is to much work, time and parts. The object is not worth that kind of attention IMO. Having no manual makes that decission even easyer.
Most parts will be recycled anyway. I will use the case to house a D-amp. I like to keep these animals inside some made from metal because of electical noise.
So it is no complete loss.
Most parts will be recycled anyway. I will use the case to house a D-amp. I like to keep these animals inside some made from metal because of electical noise.
So it is no complete loss.
@adason
because I decided this while I was at it. I also had not realized, until today, that the end of analog FM is so near, making any tuner useless in Germany next year. Major stations already get switched off this year, to make room for digital channels.
Even our 1998 VW Rabbit got a DAB2 head unit when its Pioneer DSP radio quit. I'm quite pissed off because all my wonderfull Becker car radios are obsolete now. On the other hand the digital radio sound is so much better I can live with it.
because I decided this while I was at it. I also had not realized, until today, that the end of analog FM is so near, making any tuner useless in Germany next year. Major stations already get switched off this year, to make room for digital channels.
Even our 1998 VW Rabbit got a DAB2 head unit when its Pioneer DSP radio quit. I'm quite pissed off because all my wonderfull Becker car radios are obsolete now. On the other hand the digital radio sound is so much better I can live with it.
Understood.
Luckily here in us it will continue.
Before you descard it, i would gently work with fm demodulator coil, and trimmer around stereodecoder. Nothing to loose, but learn.
Luckily here in us it will continue.
Before you descard it, i would gently work with fm demodulator coil, and trimmer around stereodecoder. Nothing to loose, but learn.
Thats what I basically did so far, but only with the coils. There are various trimpots, but nothing written on the pcb to identify them. The MPX coil had no influence at all, so I thing there are other components loosing their value. I had this tuner for about 25 years and this problem started hardly noticeable first and got worse over time. So no defect, but presumably some electrolitycs are slowly changing their value. As no obvious signs point to a specific part, I would have to replace all caps. The tuner is perfectly clean and inside it looks like the lid was closed yesterday, not 1979.
Anyway, with no FM any more, while the world is turning to streaming and digital radio, it is quite useless to repair it.
My Onkyo Integra, the second best reference tuner of its time, would be something else. The sound is so much better and musical, it would be the one to repair. Anyway, with its different FM frequency range, it is not even interesting in North America.
I have so many things on my list, that FM tuner do not even have a low priority. I just thought of using it in the workshop last evening, after installing a new wall plug for Sat, TV and Radio. The "new" digital transmissions do still use the same frequency, so I just thought why not plug it in. That was when I started this thread.
They planed to finish FM years ago and prolonged it so many times that I lost track of what was the next plan. Like import tarifs, a neverending On/ Off story, but now that the end is real, no one noticed. It still seems unreal to me, that that after all this time and my whole life with FM radio, it now disapears without further notice. The Swiss have already finished analog FM last year. Millions of car radios are just useles now.
If you are over 60 years, like me, it may get time to make your life a little leaner. Not anything you have collected over the years is really a collectable. Also, keeping things for spare can get messy over time. I think I will not repair the 40 year old angle grinder any more, or need any parts from it, even considering I paid a fortune back in the days.
So instead of repairing useless things, I will install some boxes to separate material for recycling and try to get rid of junk.
Sometimes you need a defective FM tuner to realize you don't live in the 1980's any more...
Anyway, with no FM any more, while the world is turning to streaming and digital radio, it is quite useless to repair it.
My Onkyo Integra, the second best reference tuner of its time, would be something else. The sound is so much better and musical, it would be the one to repair. Anyway, with its different FM frequency range, it is not even interesting in North America.
I have so many things on my list, that FM tuner do not even have a low priority. I just thought of using it in the workshop last evening, after installing a new wall plug for Sat, TV and Radio. The "new" digital transmissions do still use the same frequency, so I just thought why not plug it in. That was when I started this thread.
They planed to finish FM years ago and prolonged it so many times that I lost track of what was the next plan. Like import tarifs, a neverending On/ Off story, but now that the end is real, no one noticed. It still seems unreal to me, that that after all this time and my whole life with FM radio, it now disapears without further notice. The Swiss have already finished analog FM last year. Millions of car radios are just useles now.
If you are over 60 years, like me, it may get time to make your life a little leaner. Not anything you have collected over the years is really a collectable. Also, keeping things for spare can get messy over time. I think I will not repair the 40 year old angle grinder any more, or need any parts from it, even considering I paid a fortune back in the days.
So instead of repairing useless things, I will install some boxes to separate material for recycling and try to get rid of junk.
Sometimes you need a defective FM tuner to realize you don't live in the 1980's any more...
Fm is still alive and well in Canada
My 45 yr old sx780 FM sounds better then digital due to crappy 128kps rate.
My 45 yr old sx780 FM sounds better then digital due to crappy 128kps rate.
Here in Germany the sound of analog FM radio stations has huge differences, independent of how near they are. Some sound like low rate MP3, some, if you got a really good tuner, are 100% audible. This started many years ago when they turned to digital storage instead of Phono and CD in the broadcast studios. I think some used low data rate to save on the once expensive HDD storage capacity.
I may add, with my simple FM antenna on the roof top (ca. 10m high) near Hamburg, I could get more stations than any tuner can store, so crowded is the analog band. Germany is very well served in most regions
So far the new digital audio broadcast (DAB2) seems to to match CD quality on most stations I can listen to. Maybe they have learned something, but this would be very unusual. At the end of the year, when analog FM is ending, we will see how that plays out. They seem to treat digital bandwith like something very precious, making the claims of better usage of the available frequency band somehow questionable.
Not anything new is an improvement for the consumer. Since my mobile phone provider switched to the new 5G standard, in many places that where just perfect before that I can hardly use my phone any more.
I may add, with my simple FM antenna on the roof top (ca. 10m high) near Hamburg, I could get more stations than any tuner can store, so crowded is the analog band. Germany is very well served in most regions
So far the new digital audio broadcast (DAB2) seems to to match CD quality on most stations I can listen to. Maybe they have learned something, but this would be very unusual. At the end of the year, when analog FM is ending, we will see how that plays out. They seem to treat digital bandwith like something very precious, making the claims of better usage of the available frequency band somehow questionable.
Not anything new is an improvement for the consumer. Since my mobile phone provider switched to the new 5G standard, in many places that where just perfect before that I can hardly use my phone any more.
Just set up small system in the kitchen. Two smaller models of MD tuners. Got one more in other location. I use these for nostalgic reasons. Otherwise i use top of the line sony fm tuner with about 90dB signal to noise due to special demodulator. Got five of those sony tuners in various system. Will donate two to a friend.
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There is plenty of jazz and latino music here in miami, but i miss good classical radio station 90.9 weta from dc. They stream online, but its not the quality of good fm tuner.
Over the years i had many stereophile recommended fm tuners, like kenwoods, sansui, technics...yes i had that analog 8 gang st-9030 tuner, which i liked a lot. I had its digital brother, but i hated it for lack of signal meter. Kenwood was great, once i tuned stereo decoder to very wide spatial presentation. Best signal meter fm tuner i had was one jvc tuner with digital dB readout, very nice. But sound was boring. Had Luxman, nad, yamaha, various models. Once i discovered sony st-s555es, i got rid of them all. Just magnum dynalab for nostalgia. No digital broadcast needed here.
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You kitchen radio will be considered High End by many...
Well, I think for your personal use, you are right. I enjoy listening to my ONKYO Integra tuner. Compared to a CD the sound is a little different, maybe "rounder" to try a description. Just like with a very good vinyl player, compared to an early CD player. I just like that for some reason.
Back many years, when we first compared CD to analog and which took us some years, in the end a high quality record player with a very good (and expensive) pick up seemed to win the race. It was a time when, with the pick up, more money really bought you a better sound.
Then CD player improved in an audiophile sense and, for me, the race was over, also because new recordings got released on CD first or on CD only.
If today I compare the sound of an average analog FM radio to our current digital broadcast, the digital wins without any chance. You only need a 50-200$ DAB tuner to get a sound only a very expensive analog tuner wil give you. You just can't integrate a reference class FM analog tuner into a 1/2 finger nail sized 2$ chip.
The question is, what data rate will be left once all the FM radio stations turn digital. In some sense this will not matter, in Europe where there is DAB there is internet as well. So even if you don't like the broadcast, you can still turn on your personal streaming service.
I just got a new cell phone contract. Anything considered phone is free and 20GB data are included, for 8$ (€) a month. So even such a basic contract is enough to have me stream audio any time I use my car. At home there is fiber channel internet anyway. So if you take the majority of listeners, no one will miss analog FM in a few years or even know about it.Just like kids can't operate a vinyl player anymore today.
Well, I think for your personal use, you are right. I enjoy listening to my ONKYO Integra tuner. Compared to a CD the sound is a little different, maybe "rounder" to try a description. Just like with a very good vinyl player, compared to an early CD player. I just like that for some reason.
Back many years, when we first compared CD to analog and which took us some years, in the end a high quality record player with a very good (and expensive) pick up seemed to win the race. It was a time when, with the pick up, more money really bought you a better sound.
Then CD player improved in an audiophile sense and, for me, the race was over, also because new recordings got released on CD first or on CD only.
If today I compare the sound of an average analog FM radio to our current digital broadcast, the digital wins without any chance. You only need a 50-200$ DAB tuner to get a sound only a very expensive analog tuner wil give you. You just can't integrate a reference class FM analog tuner into a 1/2 finger nail sized 2$ chip.
The question is, what data rate will be left once all the FM radio stations turn digital. In some sense this will not matter, in Europe where there is DAB there is internet as well. So even if you don't like the broadcast, you can still turn on your personal streaming service.
I just got a new cell phone contract. Anything considered phone is free and 20GB data are included, for 8$ (€) a month. So even such a basic contract is enough to have me stream audio any time I use my car. At home there is fiber channel internet anyway. So if you take the majority of listeners, no one will miss analog FM in a few years or even know about it.Just like kids can't operate a vinyl player anymore today.