Klh 21?

[YamahaFreak]

The radio finally came today. Address confusion...

Anyway, there is no sound or power. So I open her up and discover that a fuse is blown(see pic). Can I just replace the fuse and be done, or do you think there's a reason it went? One of the large caps appears to be leaking as well, but I'm not entirely sure.

[Jeffhs]

Originally Posted by YamahaFreak

The radio finally came today. Address confusion...

Anyway, there is no sound or power. So I open her up and discover that a fuse is blown(see pic). Can I just replace the fuse and be done, or do you think there's a reason it went? One of the large caps appears to be leaking as well, but I'm not entirely sure.

Nine times out of ten there is a reason why a fuse blows; a low-resistance short in a large component such as a power transformer, for example, that draws more current than that for which the fuse is rated. However, fuses sometimes open for no apparent reason; a very old fuse may open simply from vibration or a power surge. Replace the old fuse and you should be back in business.

The large capacitor that appears to be leaking probably is leaking, and should be replaced. This may be why the fuse in your radio blew in the first place; if the cap is leaking it may be shorted as well. Since these large caps are usually filters and are connected directly across the AC line, if they develop a short the fuse will blow immediately upon plugging the device in (the power switch does not even have to be turned on).

I'd replace that leaking capacitor before doing anything else to your radio. Whatever you do, however, do not, under any circumstances, bypass the fuse. This dodge may get the radio playing again, but the short or other circuit problem that blew the fuse is still there and will cause serious damage to the circuitry, anywhere from burning the insulation off wiring to destroying parts to starting a fire. Years ago, many house fires were started when people would bypass blown fuses in their home's fuse box with a copper penny (before modern breaker panels, which are constructed in such a way that they cannot be corrupted). The dodge restored the electricity, but if the appliance or other device that blew the fuse was still connected to the circuit the fuse protected, the bypassed fuse would allow a huge amount of current to flow through the house wiring, often starting fires behind the walls. The rule of thumb for fuse replacements is simply this. Allow yourself one, and only one new fuse when troubleshooting a radio, TV or other device. If the replacement blows, unplug the cord and start looking for shorts.

Do not try to operate your radio without the filter capacitor in the circuit. I don't think it will do any harm; however, it is pointless, as the filters are there to eliminate ripple in the power supply's output, which in turn eliminates hum in the sound. The radio may work without the filter in the circuit, but who wants to listen to radio programs through 60-Hz hum that may be as loud or louder than the program itself?

[jk222]

Does anyone know what kind of material the grille cloth for the KLH Model 21 radio is made of? Mine is in nice condition but could use a little cleaning. Any suggestions?

[YamahaFreak]

Originally Posted by jk222

Does anyone know what kind of material the grille cloth for the KLH Model 21 radio is made of? Mine is in nice condition but could use a little cleaning. Any suggestions?

Unfortunately, mine no longer has its grille cloth. It looks like a tweed material. If it's just a light cleaning that's needed, a once-over with a damp rag would probably do the trick. Anything major and you might be better off gently scrubbing with a damp toothbrush.