Needed: Help Diagnosing Weak R Channel on HK Citation 14 Tuner
 

Needed: Help Diagnosing Weak R Channel on HK Citation 14 Tuner

I have a Harman Kardon Citation Fourteen Tuner... the R channel only
puts out a very weak audio.. can hear music, but only high freq and
very faint.. If anyone can give me some ideas on how and where to try
and diagnose what's causing weak R channel, would greatly appreciate..
L channel is fine and strong.

Also, pulled out the 2 blown lamps behind meters.. part # CM 1813 but
no values... anyone know values of replacement bayonet type bulbs?

Thanks for any help.. Greg in Chapel Hill, NC

You're lucky, you have a good channel to look at. With a scope or signal
tracer, compare the L chan to the R chan, going from input to output,
with an audio signal into both channels, until they don't match. Ken

unc80 wrote:

Needed: Help Diagnosing Weak R Channel on HK Citation 14 Tuner

I have a Harman Kardon Citation Fourteen Tuner... the R channel only
puts out a very weak audio.. can hear music, but only high freq and
very faint.. If anyone can give me some ideas on how and where to try
and diagnose what's causing weak R channel, would greatly appreciate..
L channel is fine and strong.

Also, pulled out the 2 blown lamps behind meters.. part # CM 1813 but
no values... anyone know values of replacement bayonet type bulbs?

Thanks for any help.. Greg in Chapel Hill, NC

You're lucky, you have a good channel to look at. With a scope
or signal tracer, compare the L chan to the R chan, going from
input to output, with an audio signal into both channels, until they
don't match. Ken

You can get that same signal by tuning to a mono signal or switching the tuner
to mono.

One "obvious" thing to check... Check your cable, and check the connections of
the right-channel jack to the board.

"unc80" wrote in message
om...
Needed: Help Diagnosing Weak R Channel on HK Citation 14 Tuner

I have a Harman Kardon Citation Fourteen Tuner... the R channel only
puts out a very weak audio.. can hear music, but only high freq and
very faint.. If anyone can give me some ideas on how and where to try
and diagnose what's causing weak R channel, would greatly appreciate..
L channel is fine and strong.

Also, pulled out the 2 blown lamps behind meters.. part # CM 1813 but
no values... anyone know values of replacement bayonet type bulbs?

Thanks for any help.. Greg in Chapel Hill, NC

I'm not familiar with this unit specifically, but if it's like most
direct-coupled power amps (basically a discrete op-amp) look for a dried out
non-polarized capacitor in the ground side of the feedback circuit. It would
cause the problem you describe.

Otherwise, look for other dried out electrolytic capacitors (the ones in
little metal cans -- sometimes with heat-shrink tubing on them).

In , on 11/03/04
at 12:25 PM, (unc80) said:

Needed: Help Diagnosing Weak R Channel on HK Citation 14 Tuner

I have a Harman Kardon Citation Fourteen Tuner... the R channel only
puts out a very weak audio.. can hear music, but only high freq and
very faint.. If anyone can give me some ideas on how and where to try
and diagnose what's causing weak R channel, would greatly appreciate..
L channel is fine and strong.

Also, pulled out the 2 blown lamps behind meters.. part # CM 1813 but
no values... anyone know values of replacement bayonet type bulbs?

Drop "1813 lamp" into your favorite search engine.

There are many techniques available. The "best" technique depends on
your imagination and available test equipment.

In any case, begin with a very detailed visual inspection of all the PC
boards and connections. A few minutes of close visual inspection can
save hours of diagnostic time. In the beginning, suspect all controls,
switches, and plug-in cables. Thump on everything with a wooden dowel
or plastic rod (take care not to bend or dislocate anything).

If you get to the diagnostic mode, you can compare the "perfect" left
channel, point by point, with the deffective right channel. Since I
have full instrumentation and some experience, I would start with a
known input signal and work toward the output, looking for the point
where the signal disappears. If I was in the field with virtually no
instrumentation, I would make a small sniffer probe out of a chopped-up
interconnect cable and a series capacitor then connect the probe to the
auxiliary input to an amplifier.

Using this probe (assuming that you have enough skill not to probe the
AC power supply), start at the output jack and work toward the stereo
decoder, comparing left and right. At some point a signal will appear
in the right channel and give you a hint. (Note that there are some
high frequency signals associated with the stereo decoder, that [partly
depending on your age] may not be audible, but they can damage
amplifiers and/or speakers)

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"Barry Mann" wrote in message
om...
In , on 11/03/04
at 12:25 PM, (unc80) said:

Needed: Help Diagnosing Weak R Channel on HK Citation 14 Tuner

I have a Harman Kardon Citation Fourteen Tuner... the R channel only
puts out a very weak audio.. can hear music, but only high freq and
very faint.. If anyone can give me some ideas on how and where to try
and diagnose what's causing weak R channel, would greatly appreciate..
L channel is fine and strong.

Also, pulled out the 2 blown lamps behind meters.. part # CM 1813 but
no values... anyone know values of replacement bayonet type bulbs?

Drop "1813 lamp" into your favorite search engine.

There are many techniques available. The "best" technique depends on
your imagination and available test equipment.

In any case, begin with a very detailed visual inspection of all the PC
boards and connections. A few minutes of close visual inspection can
save hours of diagnostic time. In the beginning, suspect all controls,
switches, and plug-in cables. Thump on everything with a wooden dowel
or plastic rod (take care not to bend or dislocate anything).

If you get to the diagnostic mode, you can compare the "perfect" left
channel, point by point, with the deffective right channel. Since I
have full instrumentation and some experience, I would start with a
known input signal and work toward the output, looking for the point
where the signal disappears. If I was in the field with virtually no
instrumentation, I would make a small sniffer probe out of a chopped-up
interconnect cable and a series capacitor then connect the probe to the
auxiliary input to an amplifier.

Using this probe (assuming that you have enough skill not to probe the
AC power supply), start at the output jack and work toward the stereo
decoder, comparing left and right. At some point a signal will appear
in the right channel and give you a hint. (Note that there are some
high frequency signals associated with the stereo decoder, that [partly
depending on your age] may not be audible, but they can damage
amplifiers and/or speakers)



I worked on a Citation tuner recently. Don't remember the model number
though. It would have been nearly impossible to trace using the comparative
channel technique. Thankfully I have service literature. It had more than
one problem, but one was a bad muting FET on the underside of the unit.

Mark Z.

"Karl Uppiano" wrote in message news:y3iid.990$Uy5.359@trnddc07...
"unc80" wrote in message
om...
Needed: Help Diagnosing Weak R Channel on HK Citation 14 Tuner

I have a Harman Kardon Citation Fourteen Tuner... the R channel only
puts out a very weak audio.. can hear music, but only high freq and
very faint.. If anyone can give me some ideas on how and where to try
and diagnose what's causing weak R channel, would greatly appreciate..
L channel is fine and strong.

Also, pulled out the 2 blown lamps behind meters.. part # CM 1813 but
no values... anyone know values of replacement bayonet type bulbs?

Thanks for any help.. Greg in Chapel Hill, NC

I'm not familiar with this unit specifically, but if it's like most
direct-coupled power amps (basically a discrete op-amp) look for a dried out
non-polarized capacitor in the ground side of the feedback circuit. It would
cause the problem you describe.

Otherwise, look for other dried out electrolytic capacitors (the ones in
little metal cans -- sometimes with heat-shrink tubing on them).

Do you have fuses on the board (especially underneath where you might
not have seen them)? I suspect a blown one may be present and what you
are hearing is crosstalk. A good place also to go is the forums at
www.audiokarma.org where there are a number of forums for both SS and
tubed vintage audio sets staffed by some topnotch service pros and
dealers as moderators. EchoWars' sticky on DC offset is a must read if
you have an old SS receiver/beast with certain balance problems. Best
of luck!

Steven

(unc80) wrote in message . com...

the 2 blown lamps behind meters.. part # CM 1813

The first two letters denote the manufacturer. "TS" is Tung-Sol. "GE"
is General Electric. "CM" is ... Curtis Mathes? I was stumped, until I
recalled Chicago Miniature Lamp, of Hackensack, New Jersey. I mean,
where else would you expect it to be?

http://www.chml.com/