AM/FM Tuner Alignment

[Huffler]

Hi,

I am new here so not sure if this is the correct forum to post in, with this question...

Does anybody know a place/person that can properly align AM / FM tuners ? and also possibly perform minor upgrades ? (when I say 'properly' I don't mean a 'peak and tweak' !)

The reason I ask is that I have a 1970 hi-fi receiver and want to make sure it is still correctly aligned after all these years !

Thanks,

[Paul Stenning]

Assuming it is transistorised and hasn't been fiddled with, then most likely the alignment will be fine still. There may be slight drift due to components ageing, but if the performance is OK then I'd leave it alone.

Remember that it is unlikely to be as sensitive or low noise as more modern hi-fi equipment so direct comparison may be misleading.

[geofy]

The reason I ask is that I have a 1970 hi-fi receiver and want to make sure it is still correctly aligned after all these years !

Thanks,

Originally Posted by Paul Stenning

Remember that it is unlikely to be as sensitive or low noise as more modern hi-fi equipment so direct comparison may be misleading.

What make is the hi-fi receiver, and does it work correctly at the moment. In which case nothing needs to be done.

I can't fully agree about a seventies units not being as sensitive or low noise as today's units, in some ways today's units don't seem as good, probably too much cost cutting, apart from maybe digital computer control of more modern units such as auto tune, auto set up, the basis design and the manufacture of semiconductors in the seventies was just as advanced as now, with MOSFETs and specialist chips and the like, and components where in general just as good.

If the unit works it will not need any realigning, the factory will have set it up for optimum performance.

Geof

[Huffler]

Ok, thanks for the replies chaps, however there are a few points to note.

This Sansui 1000X (hi-fi) receiver is 38 years old, I have already changed most of the electrolytic capacitors in it as the originals are past their best by a long way. (based on ~20 year life for an electolytic produced in 1970). The receiver certainly 'works' now, after changing a blown output transistor and a couple of drivers on one channel, and now sounds very nice. However, I am not convinced it is at the top of its game alignment wise, hence my question... Is there no one who has an FM/Multiplex stereo signal generator, scope, DVM, Audio signal generator who can check re-align such a tuner? I can tell you that if I had the equipment I could probably do it myself, as I have the service manual for the 1000X, and I am familiar with a wide range of test equipment - but no direct experience of the first item of test equipment quoted.

The 1000X is probably not the finest candidate to make a fuss about, but I have it in mind to purchase a very highly regarded FM Tuner (again Sansui) cost probably £200-300whose alignment I will definitely want to have checked.

So now you know a lot more about the basis for my original question...

John

[geofy]

Sansui where never the top range hi fi, but alignment of transistor equipment seldom needs rechecking, even if chips or transistors are changed, as negative feedback systems compensate for slight differences.

You can really do far more harm than good if you start adjusting ferrite cores and so on. They really don't need it, if the tuner doesn't work too well it is more likely the aerial that needs looking at

This really is a case of unnecessary work, if it ain't broke don't fix it. And even electrolytics made in the seventies will last longer than twenty years.

If proper equipment is available, and this ideally would include an oscilloscope and sweep generator to visibly look at the IF and decoder waveshape and if you wanted to gain experience in alignment then it would of course be better to do it on this set than a newer one. As the set has blown output devices in the past it must have had a hard life as it is quite difficult to damage transistor amps if used at reasonable levels.

Geof

[Sideband]

I'll second that! Valve FM stuff did tend to drift around and I have aligned many a valve tuner and IF strip. However the transistorised stuff has never needed aligning even after replacing transistors and IC's. Even MPX decoders don't seem to be affected by IC/transistor changing.


Rich.

[Huffler]

Blown transistor
The damage to one of the output transistors (& drivers), was I am sure associated with the utterly ridiculous 'repair' done by someone when they broke the panel mounted fuseholder for one of the output pairs, (quasi-complimentary) and replaced both fuseholders with soldered in, uninsulated PCB mount fuse holders (with separate clips !) onto the end pins of the originals !!! (so replacing a fuse then meant taking off the bottom cover)

Alignment
You surprise me when you say transistor tuners don't generally need re-alignment - it's a fair enough point of view, but I do want to know if it is correctly set up - that's just the way I am. I suppose when a 'Heptode' and an 'Octode' tell me this I should call it a day - but I still want to know.

Sansui
As for Sansui never being top of the range - because of the excellence of some of their equipment, they now have a considerable following, of which I am one.

John

[geofy]

You have done well to repair the unit and replace these bodged parts! It is amazing just how some will bodge a repair with totally unsuitable parts possibly making it dangerous.

But what are the 'symptoms' that make you think the alignment needs redoing. If you get a stereo beacon light come on then it is receiving stereo, and this will need a good signal as it has to pick up the 19K pilot tone for the decoder, a poor signal will result in noisy background on the best of tuners. Switching to mono will improve the sound as it switches off the decoder sum and difference channels. Of course then it will be mono.

Sansui are quite acceptable, so if you like them then that is great.

Geof

[Brian R Pateman]

This thread seems to have drifted far enough from the original question to merit closure.

Regards,