Cleaning Tuners

[cdmarion]

Does anyone have a preferred method of cleaning TV tuners, I have an Admiral chassis 21L1 and need to clean the tuner. Are there any do's or dont's? Removal or Installation specifics?

I'm nearing the end of my first TV project, I'm hoping to fire it up Sunday. I'll post the details then.

Chris

[Old1625]

DeOxIt D5 and work the knob would probably do the trick to get the heebie-jeebies out of channel switching. But the "purists" among us would probably insist on a more in-depth approach, as spraying tuner lube willy-nilly can potentially screw up any mica-compression trimmer caps if any are used instead of the cylindrical type comprised of a ceramic sleeve, and that detuning is a danger. I've never encountered such problems with "spray and twist" technique meself. One needs to use good judgement, and not empty the entire aerosol can into the thing, of course....sparing application should suffice with D5

The last Admiral set I had done any major work on (HL3) used a "standard coil" tuner, where the coils for each channel rotate on a drum, placing one coil against a battery of contacts up by the tube sockets and their associated components. Generally the vigorous wiping action associated with channel changing keeps the contacts free of tarnish. But most tuners of that design have a bottom cover that is easily removed, exposing the coil drum, where thoughtful application of a pencil eraser on the contact knobs will go far in restoring stability. IIRC In some of the tuner models the entire shaft and drum assembly can be removed after some wire retainers are loosened. In this case the stationary contacts can also receive the same attention.

How far you want to go with this depends largely on your degree of ambition and your assessment of your skills.

But while I have gone that deep into a tuner many times in early days at this point I'd probably say "Shucks, life's too short for this BS." and grab the D5 and give 'er a little squirt and a few twists. Probably all it really needs. With the tuners that have rotary switches and stationary coils the squirt-and-twust method is probably your best shot, as diddling around in one of those with all the delicate free-form coils hanging out in there can open up a very unpleasant can of worms due to detuning.

As far as doing any work involving R&R of the tuner you need to be sure that all lead dress is exactly as you found it when you started. The IF signal is usually drawn off through an RCA connection, but filament, B+ and AGC lines usually solder onto feedthrough capacitors embedded in the tuner chassis. Care must be used in desoldering/resoldering in that excessive heat or force are not suffered by these components. Inside the tuner use extreme care that any free-form coils or any leads are not in anyway repositioned or reshaped, as such are critical in the tuning of the circuitry involved.

Many TV men in the old days never went inside a tuner to any great depth, but just removed it and sent it to one of numerous agencies that would exchange it for a reman to stick in its place. People here may chime in on this and perhaps differ--and I hope they do, but my gut feeling on this is that such services may no longer be available for that type of tuner.

Hopefully others will chime in and offer light from different angles on this, but the above observations have always worked well for me.

[radio63]

Hi,

I've always taken the metal cover off the tuner and carefully sprayed contact cleaner on the contacts as I turn the tuner. Also rotate the tuner in both directions to work the cleaner onto all contacts. I have heard the pencil eraser method is very helpful but have never done it myself. I guess a good method would be to clean contacts with a pencil eraser and then spray with contact cleaner (tuner lube, De-oxit, etc.) and work the tuner back and forth, being very careful as Old1625 said earlier not to get any cleaner into the coils or inner workings of the tuner or that could cause a ton of problems.

Gilbert

[Dan Starnes]

I have done the pencil eraser and that has worked great. Also used the spray cleaner spareingly with no problems.
Dan

[peverett]

I have alway followed a similar method as given by old1625 with good results.

However, I have one now that I am not sure how I am going to handle. This one, from a 1964 Westinghouse portable, has all of the fine tuning adjustment screws stripped. I think that this is due to the deterioration of the plastic threads over 44 years, not someone with a screwdriver. As I plan to put this on a ASTC tuner, I only need to get channel 3 working. I am thinking of possibly somehow adusting the channel 3 screw and then gluing it. Not sure yet.

[Old1625]

Originally Posted by peverett

I have alway followed a similar method as given by old1625 with good results.

However, I have one now that I am not sure how I am going to handle. This one, from a 1964 Westinghouse portable, has all of the fine tuning adjustment screws stripped. I think that this is due to the deterioration of the plastic threads over 44 years, not someone with a screwdriver. As I plan to put this on a ASTC tuner, I only need to get channel 3 working. I am thinking of possibly somehow adusting the channel 3 screw and then gluing it. Not sure yet.

I surmise you are talking about a "bandswitch"--rather than "standard coil"--tuner, the bandswitch type having stationary coils, and mica compression trimmers usually accessible through a righ of holes at the front of the tuner housing, and usually accessible in sets by pulling the knobs and weilding a long shank screwdriver. Mebby I'm wrong.... Anyway, the screws on the type I'm trying to describe were once of brass, and I vaguely remember perhaps seeing some nylon ones in later models--'64 sounds about the right year for such nonsense. While it may be complicated as a procedure, and much like building a model ship in a bottle, you might try retrofitting the nylon screws with the brass ones fitted with insulating washers.... (?)....threads should be the same, one would at least like to think.....

But easier would be simply to try to find a tuner that would fit in that has the brass screws instead of the nylon ones--supposing they are lying around on the open market begging for homes.... Not an enviable spot you're in... But--on the bright side--you will be needing the external tuner in about a year from now anyways....

[peverett]

The tuner is as you describe. The problem is not the screws, they are metal. The ring holding the screws is made of plastic and the plastic threads inside of it have degraded. Behind this ring, there are small coils that the screws formerly moved in and out of when adjusted.

I do have some parts tvs of similar vintage and design, but the plastic on these is probably deteriorated also, I have not checked.