Anyone got a LAB1000?

Has anyone here got a LAB.Gruppen LAB1000 amp? I've got one which I'm repairing at the moment and need to know something about its behaviour.

Other than the faults which I've already fixed, when you switch the amp off, the fans continue to run and slow down as the capacitors discharge (if this is normal, it seems like a good idea - keeps on cooling the amp) but I still get output (if I leave the gain up and keep feeding a signal in), which gradually degrades as the reservoir capacitors discharge. This seems a bit odd on a professional, high quality amp like this - I would've thought there should be some kind of muting circuit which kicks in when you switch the power off.

Also, there doesn't seem to be any kind of power up delay, but there aren't any bangs or thumps or anything, so maybe it doesn't need one.

I've got a service manual for it, but it's not particularly informative. Just parts lists, schematics and PCB layouts. Nothing like the detail which Crown, C-Audio and others put into theirs.

Can anyone shed any light on the lack of muting?

Cheers,

Wrighty

Yeah, if I could work out which bit was the soft start from the schematic, I could check it! The service manual has zero description of how any of it works.

As you say, using the reservoir caps to make the fans run on is a good idea. I always let the amps run on after a gig anyway (with crossover muted), but an in-built system which is effective even if the mains plug is pulled is an excellent idea. There's quite a bit of energy stored in those caps too!

seanpaul wrote: [...] i bought two LAB1000s. sounds great but the fans are gone gone. [...] still trying to figure out which fans i can replace them with.

Hey! What kind of "gone gone"? Rattly gone? No starty start gone? I've rescuscitated a lot of fans over the years. If they are using a sliding scale of voltages and the default voltage is 9V or 10V, then it's pretty safe to assume it'll be a 24V fan. That's around-about where they start spinning. 

I like the Noctua iPPC fans, but unfortunately, they don't come in 80mm. So hence, try and resuscitate the current ones if possible! If you're not sure, post an audio clip or a video or alike. I'd be happy to chime in!