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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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KLH21 that will not tune stations, need help
I have a KLH21 serial # 01237, so it is near the beginning of the run.
makes noise like a radio, hiss and all that, but will not tune a FM station. I checked all the antenna connections and that all looks good. I would like to get it repaired....... thanks Shell tesla110v -- |
#2
Posted to sci.electronics.repair
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KLH21 that will not tune stations, need help
I have a KLH21 serial # 01237, so it is near the beginning of the run.
makes noise like a radio, hiss and all that, but will not tune a FM station. I checked all the antenna connections and that all looks good. I would like to get it repaired....... Take a look at the following: http://antiqueradio.org/KLHModelTwentyOne21FMRadio.htm Also, dig around on http://fmtunerinfo.com As suggested on the article on the antiqueradio site, a fairly common problem in older FM radios/tuners is that they develop bad contacts in the air-variable tuning capacitors. The metal shaft of the capacitor (which is connected to the tuning knob, and to the movable "vanes") is normally connected to ground via some sliding contacts - metal "fingers" located where the shaft goes through the metal body of the capacitor. The "fingers" are connected to the metal body, and are supposed to rub against the moving shaft and make a good electrical contact. Over the years it's common for dirt, dust, dried-out lubricant (oil or grease), and oxidation to build up on the ground fingers and the end of the shaft. This gunk interrupts the electrical contact, and the "tuning" of the radio becomes scratchy, noisy, irregular, or completely unstable. This may be what has happened to your KLH. The fix for this is fairly straightforward - flush out the gunk, restore good contact, and lubricate. A lot of people swear by Caig Labs "DeOxIt" spray for this... the D-5 spray is about 5% of their cleaning material mixed with a solvent. Note - do not "go crazy" and spray this stuff all around the tuning capacitor - you do *not* want a residue of this on the plates or vanes, as it will de-tune the capacitor and possibly make things worse. Instead, carefully spray a small amount of it into a small dish or bottle cap, then transfer a few drops of the liquid to each contact point on the capacitor shaft. Rotate the cap through its full tuning range a dozen times or so, allowing the DeOxIt to break up and dissolve the accumulated gunk and oxide. That may be enough to restore your radio to usability. I personally prefer to use DeOxIt to restore the contact, then flush it out of the capacitor entirely with a "no residue" contact cleaner, then add a drop of a lubricant such as FaderLube. Other people think this is unnecessarily-complex overkill. If cleaning the tuning cap contacts doesn't restore the radio to life, and you can't find any broken wires, then you'll need to take it to a technician who has the experience and equipment to do a repair and re-alignment. The fmtunerinfo site has leads to some shops which still have the necessary skills. |
#3
Posted to sci.electronics.repair
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KLH21 that will not tune stations, need help
On 30/03/2015 07:21, Dave Platt wrote:
I have a KLH21 serial # 01237, so it is near the beginning of the run. makes noise like a radio, hiss and all that, but will not tune a FM station. I checked all the antenna connections and that all looks good. I would like to get it repaired....... Take a look at the following: http://antiqueradio.org/KLHModelTwentyOne21FMRadio.htm Also, dig around on http://fmtunerinfo.com As suggested on the article on the antiqueradio site, a fairly common problem in older FM radios/tuners is that they develop bad contacts in the air-variable tuning capacitors. The metal shaft of the capacitor (which is connected to the tuning knob, and to the movable "vanes") is normally connected to ground via some sliding contacts - metal "fingers" located where the shaft goes through the metal body of the capacitor. The "fingers" are connected to the metal body, and are supposed to rub against the moving shaft and make a good electrical contact. Over the years it's common for dirt, dust, dried-out lubricant (oil or grease), and oxidation to build up on the ground fingers and the end of the shaft. This gunk interrupts the electrical contact, and the "tuning" of the radio becomes scratchy, noisy, irregular, or completely unstable. This may be what has happened to your KLH. The fix for this is fairly straightforward - flush out the gunk, restore good contact, and lubricate. A lot of people swear by Caig Labs "DeOxIt" spray for this... the D-5 spray is about 5% of their cleaning material mixed with a solvent. Note - do not "go crazy" and spray this stuff all around the tuning capacitor - you do *not* want a residue of this on the plates or vanes, as it will de-tune the capacitor and possibly make things worse. Instead, carefully spray a small amount of it into a small dish or bottle cap, then transfer a few drops of the liquid to each contact point on the capacitor shaft. Rotate the cap through its full tuning range a dozen times or so, allowing the DeOxIt to break up and dissolve the accumulated gunk and oxide. That may be enough to restore your radio to usability. I personally prefer to use DeOxIt to restore the contact, then flush it out of the capacitor entirely with a "no residue" contact cleaner, then add a drop of a lubricant such as FaderLube. Other people think this is unnecessarily-complex overkill. If cleaning the tuning cap contacts doesn't restore the radio to life, and you can't find any broken wires, then you'll need to take it to a technician who has the experience and equipment to do a repair and re-alignment. The fmtunerinfo site has leads to some shops which still have the necessary skills. Another fairly common source of this sort of problem is silver migration in those little 3/6 pin ceramic resonator filters, so going resistive and leaky |
#4
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KLH21 that will not tune stations, need help
On Mon, 30 Mar 2015 19:14:36 +0100, N_Cook wrote:
On 30/03/2015 07:21, Dave Platt wrote: I have a KLH21 serial # 01237, so it is near the beginning of the run. makes noise like a radio, hiss and all that, but will not tune a FM station. I checked all the antenna connections and that all looks good. I would like to get it repaired....... Take a look at the following: http://antiqueradio.org/KLHModelTwentyOne21FMRadio.htm Also, dig around on http://fmtunerinfo.com As suggested on the article on the antiqueradio site, a fairly common problem in older FM radios/tuners is that they develop bad contacts in the air-variable tuning capacitors. The metal shaft of the capacitor (which is connected to the tuning knob, and to the movable "vanes") is normally connected to ground via some sliding contacts - metal "fingers" located where the shaft goes through the metal body of the capacitor. The "fingers" are connected to the metal body, and are supposed to rub against the moving shaft and make a good electrical contact. Over the years it's common for dirt, dust, dried-out lubricant (oil or grease), and oxidation to build up on the ground fingers and the end of the shaft. This gunk interrupts the electrical contact, and the "tuning" of the radio becomes scratchy, noisy, irregular, or completely unstable. This may be what has happened to your KLH. The fix for this is fairly straightforward - flush out the gunk, restore good contact, and lubricate. A lot of people swear by Caig Labs "DeOxIt" spray for this... the D-5 spray is about 5% of their cleaning material mixed with a solvent. Note - do not "go crazy" and spray this stuff all around the tuning capacitor - you do *not* want a residue of this on the plates or vanes, as it will de-tune the capacitor and possibly make things worse. Instead, carefully spray a small amount of it into a small dish or bottle cap, then transfer a few drops of the liquid to each contact point on the capacitor shaft. Rotate the cap through its full tuning range a dozen times or so, allowing the DeOxIt to break up and dissolve the accumulated gunk and oxide. That may be enough to restore your radio to usability. I personally prefer to use DeOxIt to restore the contact, then flush it out of the capacitor entirely with a "no residue" contact cleaner, then add a drop of a lubricant such as FaderLube. Other people think this is unnecessarily-complex overkill. If cleaning the tuning cap contacts doesn't restore the radio to life, and you can't find any broken wires, then you'll need to take it to a technician who has the experience and equipment to do a repair and re-alignment. The fmtunerinfo site has leads to some shops which still have the necessary skills. Another fairly common source of this sort of problem is silver migration in those little 3/6 pin ceramic resonator filters, so going resistive and leaky The KLH 21 was designed by Henry Kloss in the late 60s or early 70s and uses IF transformers. Maybe it wasn't sold in the UK. --- This email has been checked for viruses by Avast antivirus software. http://www.avast.com |
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