tuning gang cleaning?

[technut]

I have a pioneer tx-7800 that has been working fine for a few years now but all of the sudden it's acting up!

It has developed a problem in the lower 1/3 of the FM tuning range, lets say 88mhz to 93mhz, it will cut in and out even with a strong signal showing on the meter.

It almost sounds like a poor connection, or like the muting circut is going active when it should not. When tuning in this range there is no background hiss between stations and only when you have a station locked in and you then work the dial back and forth a little will it suudenly give audio output.

Once it is working, it continues to put out sound with no problem, and still sounds fine. So my question is: does the tuner gang itself have something to do with this or is it an alignment problem?

What is the best way to clean a tuner gang? I have heard other members say that contact cleaner is not a good idea, does anyone have a personal favorite that is safe to use?

 

[Hilltroll67]

Use the search function at the top right of the page. Advanced search. Search by user name. Colortel. One of his posts is "Noisey, Sensitive, Tuning on Marantz 4400".

Bob

 

[seadzz]

Do not spray anything on the fins of that tuning capacitor...maybe compressed air but no chemicals.

What you need to do is clean the contact areas of that capacitor. The photos below show the locations to spray a cleaner like DeOxit. The pointer is actually a tooth pick but this is where the dirt is. Turn tuner off and unplug. Spray cleaner where indicated then move tuner across the tuning range the normal way.

good luck,

sdz

 

[technut]

Thanks seadzz, I will give that a try!

Hilltroll67: thanks for the thread keyword to search for.

 

[spaceman]

When I get dirty gear, I just spray on some good old isopropyl alcohol, from any old spray bottle. Mine's an empty Windex. :yes: Generally, I like to angle the PCB in such a way, that the alcohol runs over the pots, switches, etc., to clean the outsides of the innards, then do all that again with windex, then deoxit your pots, switches, etc. This is required sometimes, when you get addicted to buying cheap used gear, lol. And oh yeah, umm, unplug it or something, heh.

 

[dr*audio]

I would like to elaborate on this cleaning procedure a bit.
1. Clean with a non-residue cleaner, NOT De-Oxit. If you use De-Oxit you will leave a residue in other places that you don't want it to go, and you will de-tune the circuit.
2. In addition to the brass contact shown, there is a contact in each place the tuning shaft passes through the tuner housing. These must be cleaned also.
3. Before cleaning, blow out the fins with compressed air to get the dust out.
4. After spraying the contacts with cleaner, work the tuner back and forth across the dial a bunch of times.
5. Allow to dry completely.
6. Now you need to apply something to the contacts as a protective film to prevent oxidation. I had used a few drops of De-Oxit in the past (NOT sprayed on) but it doesn't last long, a few months later and it needs cleaning again. The manufacturers used some kind of grease but nobody seems to know what it is. I am now using CAIG MCL, which is really made for this kind of application. I haven't been using it long enough to know it's staying power, but it's what I'm recommending now. Only one or 2 drops on each contact. Any more will attract dust. Experiment with operating the sprayer, or put some in a syringe.

 

[Andyman]

I've used isopropyl alcohol and an artisits brush on the fins and it has worked well.
Do NOT use anything else as it may leave a residue ythat will mess up the tuner. There's several tales of woe here about folks who tried WD-40 and the like with disasterous results.

 

[Vinyl Rules!]

What About Everclear?

I've used isopropyl alcohol and an artisits brush on the fins and it has worked well.
Do NOT use anything else as it may leave a residue ythat will mess up the tuner. There's several tales of woe here about folks who tried WD-40 and the like with disasterous results.

A question:

Would Everclear grain alcohol (190 proof) work better than isopropyl?

(Assuming one does not imbibe!)

 

[dr*audio]

I have used IPA and found it didn't clean well enough. A real non-residue contact cleaner is best.

 

[Lefty]

Well I've read from some that nothing should be sprayed into the tuner assembly, just too much chance on detuning the many small coils and trimmer caps that are always in close proximity of the fins. They suggested using contact cleaner applied from a Q tip and only applying it at the gang contact springs and the end bearings. Never had a need to do this on any of my tuners or reciever so take it for what it's worth, just be careful.

We had more then on inexperianced hobbyist report they turned a slight problem into a unusable tuner by spraying away with a can.


Lefty

 

[dr*audio]

I should qualify that you should spray as small an amount as possible. You don't want to leave a puddle beneath the tuner if you can help it. Don't freak out if you do, it will evaporate and should cause no harm.

 

[Hilltroll67]

"studies have found..."

A question:

Would Everclear grain alcohol (190 proof) work better than isopropyl?

(Assuming one does not imbibe!)

There seems to be some documentation that isopropyl is a better solvent than ethanol. This may or may not be influenced by the sentiment that ethanol should not be wasted on external applications.

Bob

 

[Paul C]

(by Dr. Audio) "The manufacturers used some kind of grease but nobody seems to know what it is."

Probably Corrosion Guard. This is used in radio gear that is exposed to sea water conditions. Good stuff. We hose out Radio Control gear with it when our model sea planes get dunked. It will protect from corrosion, will not hurt anything.

 

[dr*audio]

(by Dr. Audio) "The manufacturers used some kind of grease but nobody seems to know what it is."

Probably Corrosion Guard. This is used in radio gear that is exposed to sea water conditions. Good stuff. We hose out Radio Control gear with it when our model sea planes get dunked. It will protect from corrosion, will not hurt anything.

Is it pale green? Where can you get it?

 

[Paul C]

"Is it pale green? Where can you get it?"

Yes, very pale green, in a little spritz bottle. Same company makes dessicant packs for electronics. Also, they have a product that is used to spray inside aircraft to prevent corrosion. The Navy uses a lot of it, for example. Used on choppers and seaplanes especially. It really wicks into tiny crevasses, and stops any galvanic action.

http://www.corrosion-control.com/acf50.html

I think this is the stuff. But our techs were getting it in 4 oz bottles labeled Corrosion Guard.

 

[dr*audio]

Cool, thanks!

 

[influx]

nothing on the fins but compressed air and gentle brushing with a soft bristle brush! Tuner bearing, contacts etc clean with IPA, then some lubricant/preservative like deoxit. You have to be conservative in this area with chemicals ( The corrosion-control stuff looks like the lubricant used in old tube tuners- I will have to check it out :scratch2: )

 

[technut]

Thanks for all the input guys!

I tried to use the best of all the ideas presented and here's what I've done: I used a non residue type plain contact cleaner on a Q-tip and cleaned the contact points, I used a paint brush and compressed air on the fins of the tuning cap, I then went back with a toothpick and a little vaseline to coat the contact points. Plugged her back in and Ta-Da! no more problems!

I will try to post later about the longevity of this cleaning and whether or not the vaseline was a good or (my)bad idea.

 

[stereofisher]

Dont use anything is the best policy!! Simple is good!!

Well I've read from some that nothing should be sprayed into the tuner assembly, just too much chance on detuning the many small coils and trimmer caps that are always in close proximity of the fins. They suggested using contact cleaner applied from a Q tip and only applying it at the gang contact springs and the end bearings. Never had a need to do this on any of my tuners or reciever so take it for what it's worth, just be careful.

We had more then on inexperianced hobbyist report they turned a slight problem into a unusable tuner by spraying away with a can.


Lefty

When I run into this problem I take a clean paint brush--NO Alcohol or anything-period. Gently run the brush through the tuner. Then run the tuner up and dowm the dial. The reciever or radio off. My big GE AM-FM-Shortwave had this problem on FM on the low end of the dial! Repeat if neccessary. Works like a charm. Did my Pioneer QX 8000 Quad three years ago. Have her in my bedroom. As everyone may already knows I am moving. The "wife factor" has been minimal. I plan to use it in our newly remoded livingroom. She got us a new cabinet to put my stuff in!!!! Kicked about the size of my JBL L100s at first. Saw how hurt I was when my contractor buddy suggested builtin wall speakers. I could have smacked him in the head!!!! :nono: My Dynacos going in the rear!! She's even building cabinets for my LPs

Anyway, I digress, my method works well. Nothing going into the tuner! If its tight I sparingly put light machine oil in the bearings. Very seldom needs it though. My tuner is very quiet. Will be the daily driver in our new livingroom. Its going to be awesome. Good luck. Eric