Harman Kardon TC

[Perry Babin]

Look at the diagram. It would be the other (non-red) outside legs.

 

[vincegironda]

Outer legs of the gain pot (opposite non red) to the caps
measures

13.82K ohm to CP204

and 13.84K ohm to CP104

 

[Perry Babin]

I missed the 820 ohm resistor but 10k+ is too much.

Did you look at the diagram?

 

[vincegironda]

R210 measures 0.819K ohm

 

[vincegironda]

I checked R110 on the other side and it measures 0.831K ohm

 

[Perry Babin]

Did you look at the diagram?

I made a mistake missing the resistor but you can see the components/circuit between the pot and the emitter. Confirm that there are no breaks between them.

 

[vincegironda]

What would cause it to be over 10k?

 

[vincegironda]

I just tested the audio on the positive legs of CP209 and CP109 and it's equally balanced and clean so I think the issue might not be in the line level amplifiers Itcould be in the power amplifier section?

 

[Perry Babin]

I re-read and I now see that you were using the wrong pots as gain pots.

So, does the gain pot work as it should?

Did you check the output level when you saw the input to the power amp was the same to confirm that the level was still uneven?

 

[vincegironda]

The gains are working, audio remains lower on the right channel.

If I pick up the audio signal on the positive legs of CP109 and CP209 the volume levels are equal when tested via a separate amp so when the gain pot is turned up the levels rise in a balanced manner.

When I test the audio from the TC amp outputs the right channel plays at a lower volume to the left.

Hope this clears up any confusion I may have caused.

 

[Perry Babin]

How much lower is the right channel? Use a multimeter to measure the audio level at the output of the 109/209 caps and measure the level across the two speaker terminals for each channel.

Post the 4 voltages.

 

[vincegironda]

Do I measure with the amp at idle with no audio signal?

 

[Perry Babin]

You have to drive a signal into it. Try it at 100Hz. Set the bass boost to 0 boost. I'd use enough signal to get the output to near clipping. That will make the readings at the input to the power amp more usable.

 

[vincegironda]

CP209 075. 5v
CP109 083.3v

R. 003.7mv
L. - 45.3mv

 

[Perry Babin]

You need to measure with the meter set to AC volts and the black probe on the secondary ground (negative speaker terminal).

As a side note, if you find the fault causing the low channel, you will have to readjust the trim pots on the input of the amp (VR103/203) to prevent having engine noise. We can cover that later but don't forget.

 

[vincegironda]

With the meter set to AC volts

CP209 0.363v
CP109 0.113v

R speaker 0.510v
L speaker 3.041v

 

[vincegironda]

I'm beginning to wonder if the right channel is OK and the left is in fact over powering? Could this be possible?

 

[vincegironda]

Noticed at high volume the left channel pops loudly every so often?

 

[vincegironda]

Pop noise is just the speaker coil at full extension hitting the magnet so ignore last comment.

 

[Perry Babin]

You stated that the voltages were equal at the caps CPx09. They are not. What's even more strange is that the right channel cap has a higher level but the right channel output has a lower level. Recheck the voltages.