Soundlab G742BA2 Powered Mixer

[GRAHAM99]

I got it for £20 including a flight case and I am using it to improve my knowledge of electronics!
I would like to get it all working again but I know what you mean about spending ages on it.
Would it be easy to source and replace the power amp modules?
I think they are 200w each.

[ef37a]

I got it for £20 including a flight case and I am using it to improve my knowledge of electronics!
I would like to get it all working again but I know what you mean about spending ages on it.
Would it be easy to source and replace the power amp modules?
I think they are 200w each.

A laudable aim G but do you really need 200W internal amplifiers? Do you have speakers that can handle that? You could get a pair of kits or a stereo amp kit from Vellemann or similar that could give you 15 or 20W per channel which would be easily enough to tell what is going on with the mixer. 15-20W per ch' into very modest hi fi speakers will knock spots off an FSTV sound system and drown a computer 'media' speaker system.
First thing is to isolate the faulty PAs from the supply rails them measure those. From that you can look for suitable amp modules although I suspect if the mixer delivered a GENUINE continuous 200W sine into even 4 Ohms, those rails will be too high for most lower power modules...Still! You want to learn!

I take it you have a half decent digital multimeter?

Dave.

[James Perrett]

The most important thing to check when thinking about replacing power amps is the power supply. Does it have +/- and 0V rails or does it just have + and 0V rails? What voltage is it giving out and do you know how much current it can supply (look at the fuse ratings for a very approximate guide)?

[GRAHAM99]

I replaced some capacitors on the power board and it now cuts out after about 20 seconds.
One of the capacitors was in a poor state.
Onwards….

[GRAHAM99]

I do have a digital multimeter!