Poor man's tuner alignment?

[ssouci]

is it possible to do any sort of "poor man's" tuner alignment on a 22XX series receiver?

I'm especially interested in the 2230 and 2275, both of which I recapped 100%

instructions for *anything* I might be able to do on my own using only a multimeter, even if it's only covering some of the basics would be great!

seems this (tuner alignment) is one area where people will even skip recapping their tuner boards because of fear of upsetting alignment and then not being able to get it redone properly


I've poked around here locally (Vancouver, Canada) for a tech that has the equipment and skills (and won't want $500!), and came up with nothing... this seems to be a dying art or something people don't want to touch

my 2275 sounds pretty darned good after the recap with no re-alignment, but my 2230's tuner is maybe not quite as good? (but certainly not horrible)... I suppose I just want to get them to perform as best I can, because I do love FM

thanks!

 

[catrafter]

While it is possible to do a rough tune up on the front end without test gear and mucho experience, things could go from bad to worse in a heart beat.
Here's a link to a post with the basics. You will need proper alignment tools to keep from breaking the coil slugs.
To align the discriminator you are definitely going to need an RF generator, low distortion audio source and a distortion analyzer. If you want to align the multiplex decoder, that's going to take an RF generator with stereo capabilities and perhaps a counter. A high impedance AC voltmeter with a dB scale makes things a lot easier.

Tom

 

[bktheking]

You need the proper gear to do it, i've been dabbling in it now for a couple of months- im still trying to find a cheap and decent distortion analyzer and may have to resort to using a pc and sound card.

 

[gadget73]

honestly unless you have the proper test equipment the best thing you can do is let it be. A proper FM alignment requires a stable sweep generator and an ocilloscope to do the IF strip, and a multiplex generator to do the MPX decoder. Am is a lot easier, and often you can do that with nothing more than a station at a known frequency and your ears but FM, and FM stereo in particular, is not quite so forgiving.

The old way of doing it in the pre-stereo days when sweep generators weren't so common was to use a fixed frequency generator and adjust a series of cans for best signal, usually measuring the AVC (sometimes called ALC) for strongest voltage. Usually the detector was set up by adjusting for zero volts across some other set of points. This just sets you up for peak throughput, not symmetrical IF response. It works, but the sound quality is usually not ideal and on a stereo set there is a very high chance of killing the MPX functions if it knocks out enough high frequency audio response.

The only thing you may be able to do with FM without any test gear is the RF amp adjustment . The RF amp you can adjust using a weak station near whatever frequency the manual says to use. Simply peak it for best reception.

 

[SoCal Sam]

The tuner techs and super hobbyists have it right. However...say you have a cheap receiver that makes no economic sense to spend for a proper alignment. There are steps you can take.

No FM stereo reception / poor signal strength can be fixed by cleaning the oscillator trimpot. Note the original position and return the trimmer after cleaning. While you are at it, this trimmer will align the gangs with the dial pointer. Sometimes the muting trimmer is the culprit. The other trimmers, leave alone.

Note: Use this tip at your own risk. I've done this with good results on many tuners and receivers to prep them for new homes.

 

[rBuckner]

The tuner techs and super hobbyists have it right. However...say you have a cheap receiver that makes no economic sense to spend for a proper alignment. There are steps you can take.

No FM stereo reception / poor signal strength can be fixed by cleaning the oscillator trimpot. Note the original position and return the trimmer after cleaning. While you are at it, this trimmer will align the gangs with the dial pointer. Sometimes the muting trimmer is the culprit. The other trimmers, leave alone.

Note: Use this tip at your own risk. I've done this with good results on many tuners and receivers to prep them for new homes.

These trimmers are variable caps of fairly / pretty low capacitance. I wouldn't use any cleaner on them myself although it may not hurt them. You can get way the heck off tune in a hurry here and of all the alignments one might mess with, this is the one I'd say to stay away from. You can slip the dial cord (it's been described before - do a search) to change the pointer mechanically which usually centers the needle's travel better. One other thing I've observed about the variable caps is that sometimes they are quite stuck and after moving them, they are loose and WON'T adjust right no matter what and have to be replaced. Hope this helps.

 

[SoCal Sam]

These trimmers are variable caps of fairly / pretty low capacitance. I wouldn't use any cleaner on them myself although it may not hurt them. You can get way the heck off tune in a hurry here and of all the alignments one might mess with, this is the one I'd say to stay away from. You can slip the dial cord (it's been described before - do a search) to change the pointer mechanically which usually centers the needle's travel better. One other thing I've observed about the variable caps is that sometimes they are quite stuck and after moving them, they are loose and WON'T adjust right no matter what and have to be replaced. Hope this helps.

Do not touch the dial string. The string is old and may break. Broken strings are a nightmare to replace. I've adjusted at least a dozen receivers and tuners using the oscillator control. Most were stuck from corrosion, which causes contact loss so cleaning was the cure. The scenario you sketch could happen but so far I have not seen this.

 

[rBuckner]

I have seen it 2-3 times in over a 100 Marantz rebuilds. Not often but it could ruin your day if your not prepared to do surgery. OTOH, I've done the string slip many times without incident and I've read of others being sucessful as well. The old soldering iron is the dial cord's worst enemy and yup, I did it once too!

 

[ssouci]

thanks everyone.... YIKES, this seems like very dangerous territory, not to mention beyond my scope of skills

I'm wondering, does swapping in all new caps really affect the alignment that much?... my 2275 seemed to have survived just fine

OR, is a tuner alignment simply part of a total restoration (and any misalignments could be caused by a whole slew of things, caps being just one of them)

 

[terra1]

It's nice to get is as good as you can, but if you don't know what you are doing you can easily make it worse and wonder why you didn't leave well enough alone. If your tuner sounds fine, consider that you may not need to do any more to it.

I have a Realistic STA-90 where the tuner sounds great. I'm pretty sure the problem is with the meter or circuits around it rather than the reception. In fact the service manual has recommendations to replace some caps and resistors or other parts if I recall, which I haven't bothered to pursue. So sometimes it may be more than just an alignment issue. It just sounds great.

If you want to try playing with alignments, try experimenting on something you don't mind messing up. But it would be good to make sure you have a service manual.

It's best to have the proper equipment. But you can get by doing some basic steps using an antenna for FM and AM signals instead of a signal generator.

I don't bother with more complicated steps involving multiplex sections which require an oscillator. You gotta know your limitations. A lot of tuners have different layouts and you can't always treat them the same.

A lot of patience and finesse to get calibration close so 101.5 shows up at 101.5. Optimizing the signal strength. Tuning meter is centered and stereo indicator goes out and on as the needle swings from center. The frustration can make manly men come close to tears.

The trick is knowing how the circuits respond. Clockwise turn, counterclockwise turn. During calibration does it move the station up or down the scale. When adjusting strength observe the signal meter needle as it pivots to maximum and when it starts to drop down. When to repeat steps. Which trimmers affect FM, AM. Sometimes you can wind up with 88.5 showing up at 104.5 on the scale. I know of at least one thread where the OP just quit.

Service manuals assume you have some knowledge and some steps are not always clear.

Those ferrite hex slugs can be quite brittle and crumble if you try to turn them. Sturdier are the screws across the top of the tuning capacitor. Know what each does. Be careful, there are some adjustments that alter the calibration and not just the signal strength.

 

[hauf888]

You start messing with those tuning slugs and you will unleash the primordial forces.....beware. There is a reason alignment costs quite a bit of money..it's hard to do right and easy to screw up. There is no such thing as doin it on the cheap...

Rosie

 

[rBuckner]

Great post terra1! Much truth in here. I have crunched my share of slugs up and robbed spares from donor units. Last summer I found some slugs on eBay and got them but haven't tested them yet to see if they are compatible magnetics-wise.

Hauf: So true!

 

[hrnoevil]

Hi Gentlemen,
I am glad I found this old thread about poor man's alignment. I have restored a Heathkit AJ-32 AM/FM tuner (well, kind of). This model has the built in FM stereo multiplex. I got AM and FM (mono) going pretty good. I used the "max. voltage/zero voltage" basic method to adjust the last "can" before the ratio detector tube (6BN8) and got the FM mono going very good. But when I switch to FM Stereo, the same station which sounds clear on mono, is out of tune in Stereo. According to the manual, the FM multiplex will be connected only when it is switched to "stereo". That tells me the problem is very likely in the Multiplex. I don't have a scope and don't know how to use one. All I have is a signal generator that can generate 88MC to 108MC. There is a pair of diodes (color bands) used in the balanced diode detector, could they be the culprits ? Can anyone point me to the right direction what I should look for in the FM Multiplex ?
Ken in Canada