Help requested to cure hum problem of preamp

Bought a $500 Twins Audio Serenade pre-amp from a DIY seller / member through this site. It has mixed, non-labelled 'GE' tubes (3 Nos 5654 + 1 No 6AK5) , loosely-mounted volume control and serious hum heard throughout all output levels except when the volume is turned fully clockwise.

My appeal to other DIY experts - please advise how the hum problem can be reduced or removed. The seller refused to look at it except to sell me more expensive products. Thanks to all those who are willing to assist.

cheapie  :cry:

Hi Cat

Thanks for your response and suggestion.  I'll be away from HK until May 1.  Will find the time and post some photos upon my return then.  

I'd like to correct myself.  The noise is more like high-voltage electrical buzzing D-noise (similar to that described in another thread regarding a Mac preamp) than hum.  It becomes loudest mid-way through the volume control and dies down at full volume.

Thanks again.
cheapie

Thanks windwss for the suggestion.  I'd look into the box when I return to HK on Apr 30.

Many thanks to all experienced DIYer for your suggestions.  I'm still out of town at the moment but will try the methods from the simplest first when I'm back to HK during the May 1 holidays.  I'm not a DIYer and am very grateful for your help.

I suppose it's a case of buyers beware.  But this guy has several listings, all preamps ranging from $500 to $2000, in the for sale market under the same name.  He trades at MTR stations, no testings allowed / arranged.  Wonder how many got burned because of him.

cheapie

Millions of thanks to the expert DIYers who have offered advice, particularly accphoto.  I spent an hour doing the simplest to my el cheapo preamp - connecting a ground wire from the 'micro' volume control to the power in ground and then to chassis - by a telephone cable core stripped appropriately and twisted to wrap around the contacts, no soldering.  

Bingo! It worked.  Please see attached photos.

cheapie :wink:

Thanks.  I intended to solder the connections ultimately.  But on May 1 morning I had to get packed for another trip and only returned late last night.  Then it's a full day's work in the office, pack and leave at 0800 for China again tomorrow.  I'll miss enjoying my equipment for the coming few months.

Hence, just a make-do and minimal work for the time being.  

cheapie