KLH Model 21 found at Goodwill today!

[WISCOJIM]

Try the new Goof Off 2. "SAFE ON PLASTIC!"

[Captainclock]

Originally Posted by WISCOJIM

Try the new Goof Off 2. "SAFE ON PLASTIC!"

OK, I'll see if I can find some.

[Captainclock]

Well I replaced the original 2000 MFD 30V Power Supply Cap in the radio with a 2200MFD 50V capacitor and its still has a 60Hz Hum coming out of the speaker and still no audio out of the speaker from the tuner. So what should I check next in the circuit that could be causing my issue? I also tried posting this in AudioKarma but for some reason when I went to post it it wouldn't post it would act like it was going to post the thread but then it would wouldn't actually post anything.

[jr_tech]

I would suspect that one or both of the diodes in the rectifier circuit could be shorted or have very high reverse leakage... you can get a manual here from Phil's old radio site:

http://antiqueradio.org/KLHModelTwentyOne21FMRadio.htm

Thanks again to Phil Nelson for his wonderful site,
jr

[zeno]

KLH built some very nice stuff. Our shop saw a lot
of it being 20 miles from Cambridge. Also piles of
H.H. Scott that was 5 miles away.
Anyhows change ALL the lytics first. I remember a few
of the stereo ones going DEAD in one channel & that
was it. ( 30 yrs ago ). Another thing that may be it
is if it uses ua703 IC's in the IF they were trouble
especially on Scotts sets. In any case when its running
again you will wonder what all the hoopla about digital is.

73 Zeno

[Captainclock]

Originally Posted by zeno

KLH built some very nice stuff. Our shop saw a lot
of it being 20 miles from Cambridge. Also piles of
H.H. Scott that was 5 miles away.
Anyhows change ALL the lytics first. I remember a few
of the stereo ones going DEAD in one channel & that
was it. ( 30 yrs ago ). Another thing that may be it
is if it uses ua703 IC's in the IF they were trouble
especially on Scotts sets. In any case when its running
again you will wonder what all the hoopla about digital is.

73 Zeno

I believe mine's an original 21 so I don't think it has any IC chips in it. The electrolytics don't appear to be bad but of course they could be bad even if they don't look it (no cap bulge). The electrolytics are mainly on the amplifier board, there aren't any on the tuner board surprisingly enough. Now I noticed that the Model 21 has an RCA Plug that says "Tuner out" was this meant to be able to have a multiplex unit hooked up to it so it could be FM Stereo like the Model 8? Also I'm missing one of the knobs on this unit and I was wondering where I might source a replacement knob for this unit.

[dieseljeep]

Originally Posted by Captainclock

I believe mine's an original 21 so I don't think it has any IC chips in it. The electrolytics don't appear to be bad but of course they could be bad even if they don't look it (no cap bulge). The electrolytics are mainly on the amplifier board, there aren't any on the tuner board surprisingly enough. Now I noticed that the Model 21 has an RCA Plug that says "Tuner out" was this meant to be able to have a multiplex unit hooked up to it so it could be FM Stereo like the Model 8? Also I'm missing one of the knobs on this unit and I was wondering where I might source a replacement knob for this unit.

The ua703, if made by Fairchild, looks like a slightly larger transistor. The brown button ones were extremely unreliable. IIRC, they were replaced by a GE-IC12, NLA.

[Captainclock]

Originally Posted by jr_tech

I would suspect that one or both of the diodes in the rectifier circuit could be shorted or have very high reverse leakage... you can get a manual here from Phil's old radio site:

http://antiqueradio.org/KLHModelTwentyOne21FMRadio.htm

Thanks again to Phil Nelson for his wonderful site,
jr

Thanks for the link, I tried to download the service manual but the link to the service manual in Phil's Website didn't work.