ML Stylos problem with ESL

[Tom274]

Hi,
I have an issue on one of my Martin Logan Stylos ESLs.

The ESL panel part can run perfect for a while and suddenly the ESL gets quiet. When I turn up the volume of the amp quite high quickly or power cycle the AC mains plug everything works fine again. This happends sometimes every day or sometimes after some weeks.

I talked to the ML guys and they recommended replacing the LM324 op amp on the board. But this did not help much. Could it be that a Cap or other component has gone bad? I am an electronics engineer and have all scematics, so could easily replace what is needed.
Thank you for any hint.

 

[stokessd]

I'm not familiar with that model, but older ones would turn off the polarizing supply if there was no music present. It sounds like your supply is turning off. So I'd look into the rectifier diodes that are rectifying the music signal, and the Triac that is turning off the AC going to the C-W multiplier.

Sheldon

 

[Tom274]

Thank you Sheldon,
there is indeed a rectifier for sensing the music going over some op amps to the triac. A second path comes from the AC transformer seondary. There is an LED in series with the gate of the triac, showing the ON status. I will look into it.


Regards,
Tom

 

[stokessd]

That LED sounds handy. When the speaker gets quiet, see if that LED is out or very faint.

Sheldon

 

[bolserst]

@Tom274,
Were you able to track down the issue? I'm curious to know what the problem was.
From your description, you experienced something a bit different than the typical failure modes.