Quad 33 and Mains dirty noise

[Beechwoods]

Over the last few months my 33 has developed mains noise on one channel that occurs whenever an input is connected to any of it's inputs. The noise isn't there when the inputs are disconnected. The noise is quiet high frequency noise and appears to be coming in after the volume control. It's not related to the tone controls at least they are switched off when I use it. The noise gets worse and changes when the hard drives in my room are on. It occurs regardless of which source is connected to which input.

Any ideas? Caps? Or would a mains conditioner of some sort help? Might it be related to the output circuit on the 33?

This is really bugging me!

[MartinT]

It's likely to be an internal problem, Nick, so a conditioner isn't going to fix the root cause. Could it be an earth connection inside that has become detached? It sounds like it has become a radio receiver which usually points to earth. Try a temporary earth wire to the chassis at the back to see if it changes. If so, you'll need to perform some surgery. Otherwise, the circuit has become unstable in some way. Could be old caps.

[DSJR]

Have you cleaned the daughter board contacts? Early 33's didn't have gold edge connectors and could give trouble, but as with Naim poreamps when they were built this way with gold contacts, jiggling the boards up and down on their pins/connectors every year or so should fix it. As it's one channel it's not the power supply.

If getting jiggy with the boards doesn't alter it, remove the output cards and swap them over to see if it's a leaky cap on one of them.

Just to also say the dada kit works and for twenty odd quid it's a good deal. Nichicon caps and better diodes which do improve things even before you do anything else.

[Rare Bird]

Hi Nick
Nice when a topic gets absolutly nowhere. However: it needs servicing which generally equates to a rebuild in my books, not that im saying thats the problem but something as old as this is best being rebuilt..Look at it this way at least old gear doenst just break down & inevitably ends up as a fridge freezer next year. :eyebrows:

[MartinT]

I think we need an update from Nick to see how he's doing with it.

[Rare Bird]

get real Martin, it needs sorting

[DSJR]

get real Martin, it needs sorting

No need for the forceful opinions here guvnor. 33's are usually kind to their components (I sold 'em when new and have had a sizeable number of different ages and conditions through my hands as well as owning a late one myself) and I don't recall seeing loads of bulging Roe caps or even knackered supply ones either.. Many here actually secretly own and use them as well from time to time..... Yeah, there's a good few closet vintage Quad owners on this forum :respect:

For many stock 33's, removal and replacing the numerous boards in the thing to clean the contacts will sort it for now. As for updates, I did the Dada one, plus the output card high pass filter and found the results much better. Others here have done the Net Audio upgrades, which makes it a.n.other preamp in a 33 case.. Quads own service dept is a bit useless here, since all they do is repair faults, often ignoring other things that could fail later - I have in mind my II's, both of which were "serviced" by Quad and a year later, one blew up and took a 57 speaker with it. After a full rebuild, they've been run gently without incident for twenty years now..

So I think we all have the OP's interests at heart. :) I think I suggested swapping the output cards over. At least this would tell the OP if there was a fault or just dirty contacts. The OP can proceed from there on the best course of action.

[Beechwoods]

Thanks everyone for your comments. In terms of progress I've not been able to do anything unfortunately. For the moment much of my gear has had to go into storage while we start on the road to selling and moving house... I think a service may be wise. Moreso after its been in storage...

[DSJR]

Yeah, storage certainly won't help and now I know who Rare Bird is, I don't feel he spoiled the fun either, since he's also a Quad owner and has been there IIRC :lol:

[Barry]

As a massive Quad fan (I own 17 items of Quad manufacture), I would contest your statement about Quad's service department.

Despite the fact that the Quad company are now a shadow of their former selves (thanks to Farad Azima selling them to Chinese ownership), the guys in the service department in Huntingdon still uphold and maintain the reputation of Quad's customer support, which was, and still is, second to none.

Over a period of thirty years, I have had to call on their services only four times and their service has been impeccable. In all cases, where a fault had to be repaired, other components that were though to be best replaced owing to their age (such as capacitors), were replaced at no extra cost.

How long this excellent service will continue I don't know - but all I can say is that when I have spoken to one of their service engineers, I have been very impressed by his knowledge, helpfulness and professional integrity, as well as with the work carried out.

[DSJR]

They "repair" a product, when IMO a full rebuild is preferred. For example, a noisy grainy sounding 303 went back to Quad and had the supply caps changed. came back quiet but still not sounding as a 303 can and should. Our own engineer had a go, replaced some more of not all of the caps and re set up and it sounded far more like it should.

Maybe Quad's service dept have changed over the years in which case, fantastic, but my opinion based on personal experience is still valid for the times I dealt with them. I wouldn't be using my II's several times a week if their service dept had properly rebuilt them in the first place for their elderly original owner :) Thanks to Glenn not going mad with them, I now am the custodian of a set of II's which sound like but better than original, coloured as heck but so enjoyable and involving when given a modern source :lol:

http://i132.photobucket.com/albums/q8/DSJR_photos/QuadIIsSept2010.jpg

[Barry]

Hello Dave,

I hear what you say, but is it reasonable to expect that a "repair" result in a full rebuild?

The only time I have come across this was when I used to have my Leica cameras serviced. I was told that the service entailed stripping the camera down to over two hundred components, each of which was examined for wear and replaced if necessary and the whole camera re-assembled.

I had to have the mains switch on a Quad 44 replaced. Whilst this was done the service engineers at Quad replaced some electrolytics.

Regards

[DSJR]

Fair enough, but those II's of mine also had one valve and a couple of caps each replaced. Some months later the bad one blew again and took a 57 speaker with it...

Andre's right here. Very old UK made gear usually needs a bit more than "just" a repair since the bits inside weren't always of the longest lasting quality. By the mid 70's, it was obvious the Japs had far better and longer lasting components available to them and classic stuff from this period and older just runs and runs for decades - usually.....

Anyway, the 33 is so modular it should be a doddle to fix with luck :)

[Beechwoods]

Thanks for your advice everyone. Stripping my system back to it's basics has cleared the noise. It must have been coming from the spaghetti of cables behind my system. Will have to be much more careful in the future.