DLK 1 1/2 Speaker issue

[tom_s]

One of the AudioKarma resident techs was from KC - he went by EchoWars. Brilliant under the hood of vintage gear, but it looks like he hasn't been active on AK for a few years.

[saabracer23]

Yeah Echowars was an excellent contributor to the community, unfortunately he had to attend to some personal affairs. There aren’t all that many that do this, I’m backlogged 3-4 months myself. Good luck getting it going. If you decide you want to try a go at it feel free to PM with any questions.

Dan

[Jav726]

Sorry to keep at this. I did some more testing and realized my initial experiment was inaccurate due to my idiocy. Here’s what’s actually wrong:

The crackling and popping was from my broken tweeter causing a grounding issue. New tweeter installed, that problem is solved.

Left channel on all four banks of speakers (A-D) on all sources (Phono-1, Phono-2, AM, FM, etc.) is almost inaudible. This is including swapped speakers on the left and right outputs. Left channel output is definitely the issue.

If this can be narrowed down to a few parts on one board, and you could help me identify it using the service manual, I may be able to tackle this myself.

PS. I have some deoxit on order but considering how clean the inside looked, I’m probably not lucky enough for that to be the only issue.

Thanks guys.

[saabracer23]

Sorry to keep at this. I did some more testing and realized my initial experiment was inaccurate due to my idiocy. Here’s what’s actually wrong:

The crackling and popping was from my broken tweeter causing a grounding issue. New tweeter installed, that problem is solved.

Left channel on all four banks of speakers (A-D) on all sources (Phono-1, Phono-2, AM, FM, etc.) is almost inaudible. This is including swapped speakers on the left and right outputs. Left channel output is definitely the issue.

If this can be narrowed down to a few parts on one board, and you could help me identify it using the service manual, I may be able to tackle this myself.

PS. I have some deoxit on order but considering how clean the inside looked, I’m probably not lucky enough for that to be the only issue.

Thanks guys.

Honestly pinning down low volume can be kind of tricky. For that fault I’ll generally trace a signal and monitor it on an oscilloscope. It could be a switch or potentiometer on the front. Best thing to do is turn each one at a time, several times and see if this causes any change. If it crackles and cuts in and out in volume while turning it then it’s likely that control. A signal transistor could definitely be the issue, but it could also be several other things like a dry solder joint, a short pulling the audio to ground, etc. I’d look at voltages to make sure you have appropriate voltage at certain test points.


I haven’t seen the inside of this unit, but there should be a pair of coax cables going from the preamp section to the input of the amplifier driver boards. You could disconnect the left channel and right channel from the driver boards. Feed a 1khz sine wave into the input of your choice (aux), turn the volume to say 9 o’clock and then measure at the coax you just disconnected. Set your multimeter your AC mV (or V depending on how load it would potentially be) and measure across that wire. If both channels have roughly the same voltage then you can assume the issues would be in the amplifier portion. If the left channel has less voltage then you can assume the issue is in the preamp section. You could try swapping the coax you disconnected between the two channels (left to right and right to left) and if the issue stays on the same channel that would tell you that you have an amp issue and if the issue goes to the right then you likely have a preamp issue.

Dan