Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems DSP 8.2K BUZZ

to remove backplate there are several issues and the plate is damn heavy. i think a housecall is in order perhaps. what a pain. why oh why so many issues? i love the sound and aesthetics but this is all too much.

what a pain.

Dealer should take care you. It is a pain I certainly would not live with it. But I believe it's a minor problem that is a little tricky to find.

The problem is you take the plate off and the noise stops, then what.

On 5.5K and 6K there are bolts in the center of that plate that hold transformer(s).

You could try snugging that up (if 8K is the same). But I forget if there is nut on the other side you need to hold. Or if it's plate with threaded hole (that unlikely will spin as you tight the other side).

I think Frank would know as he had a pair of those 8K power plates.

Removing the back plate of a 8k is easy. I have done it many times to have a peek. You just need a good star screwdriver and patience as there are lots of screws. A big book to rest the plate on as it loosens is also a good idea as the wires are not long enough to allow it to rest on the floor.

I suggest unplugging all the wires in the back and replugging.

howie

IIRC, you need to take the main panel off before you can pull the power supply panel. Just keep track of the screws, be patient and you'll be fine.

Agreed, that may be all that's needed. Push them on and off a few times.

Make sure no pins or sockets are "pushed" in and they are all lined up.

Sometimes they don't get locked in and when you push it on it backs out of the connector making poor contact, that was not my problem but that can happen.

Thanks everyone. yes of course I unplugged and plugged all wires and cables and did all the steps going into the backplate and even used different power cables and plugged them directly into wall. I tightened the bolts clockwise to no avail. BUT there is no way I'm going to take off the backplate without the replacement here since I want to do this once and only once -- if pushing in the internal plugs works with pre-existing unit then I won't even open the replacement box but to me this is more of a chore and not fun.

I will have a book and towel under the defective backplate. i think this should be cake upon further inspection. what size star bit do i require?

I would not expect a "spare part" until dealer isolates the problem, that would be dumb. It could be a bad connector on the transformer plate or problem on power distribution board or even further in.

I suspect they will send your panel(s) back if they can't isolate it immediately. You really want to keep your same panels as everything is a matched pair and vintage.

They might have a spare transformer plate but they are not gonna have spare new back panels sitting around and sending you one on hunch.

I had the same problem. As soon as a song started it would be dead silent. When the song stopped, it would still be dead silent. But about 10 seconds later, the buzz would return. The reason was that the source was letting one of the connections float about 10 seconds after being put in standby. The buzz only happens when the source cable is plugged in. This process is repeatable 100% of the time.

But dr. Bill says that the buzz is still there with the source cable unplugged. Therefore, its not the source.

I also have a buzz in my sub 100% of the time with power only and no source or comm cables plugged in. This is more in line with dr. Bill's 8ks. I fixed this by putting the sub in manual mode (defeat switch set to off) and then turned down the crossover frequency and/or gain knobs. But I don't think that the 8ks have any manual gain settings.

Dr.Bill& Jerry,

good news.I dit remove my power plarte and check that out for you:
You can tighten the cap head screws but in different way as I described in my private mail.
You dont have to remove the powerplate, just take a 5mm hex key and CAREFULLY turn the screw clockwise about 1/8 of a turn.
Then try if the hum is gone.
If not you can try once again but not more as on 1/8 turn clockwise.
If you feel more resistance before 1/8 turn dont turn further.

One thing is to check that the whole power plate is not to deep mounted on the cabinet.
If this happened,then the bigger transformer touches the cabinet inside the cabinett opening.
The correct height is when there is a small gap between the top edge of the power plate and the cooling case of the electronics(not more then 2 mm.
Also the lower edge of the power plate have to be at the same height or above-never below-
the bottom of the cabinet.

If that is the case,you have to loosen the 3upper and 3 lower screws and push the power plate up to the correct height(heavy !!) and then tighten it.
Take care at the same time to make equal gaps on the left and right edges.

Also check the six screws that holding the power plate if they are tight,but dont overtighten it.
In this area of the cabinett "only" wood is there.Take care.

If the hum is still there,then it could be

a) DC on the power line(but a DC Voltmeter in the range of 700 VDC-not less as then your measurent is wrong!!) as one transformer is maybe more sensitive as another.

b) Transformer is "biased" (could happened)

c)As George described, loose connection-I have no experiences with that.

Good luck

Robert

Picture of my DSP 8k back plate

I can't quite remember, may be a 12? Honestly don't worry too much about taking off the plate, it really is simple as loosening all the screws. You might also want to check the fuse box is accesible from the outside just near the power switch to make sure there is nothing fishy going on there. My guess is that it is a transformer problem. loosening the central screw holding the transformer down, giving it a shake and retightening is very quick but you need the back off to do it.

The great thing about the Meridian architecture is that the back plate only has two connections and both are serial type connections so they are easy to unplug and plug back in. No soldering or worry about broken wires etc etc.

Give it a go. You will be surprised how simple it all is.

howie