Some odd effects can occur with these devices,the most recent for me was no sound on one channel,due to one of the internel ldr's behaving strangely.

The device works by having a lamp arranged to shine light upon the ldr's dependent upon volume level

Minimum volume means max brightness,which means(or should!)minimum resistance of the ldr's which are arranged to "shunt" across the signal supply.

In my case,one of the ldr's was reducing to minimum resistance regardless of light level,hence the no sound on one channel.

When the unit was unpowered or the volume moved to max,the resistance increased to infinity as expected!Weird or what?

The device can be dismantled with care,and after some experimenting,I found a ldr with similar electrical characteristics to the originals.The ldr that I used is smaller than the original,and I assume less light sensitive because of that,as I found I needed to increase the preset brightness level to achieve the correct action.I replaced all four of course,having checked their spec to determine that they were all similar before fitting.

Overall though,a good result.The ldr I used was a generic GL5516,although the crucial consideration seems to be that minimum (illumimated) resistance is approx. 300ohm.

I imagine that the above could also apply with BM1900-2 and 2400/2400-2,as I think these units employ the same system.

Regards,

Nick