Fuzzy rcf art300a (mk1)

[Va joiner]

Good'ay mate :-)I've been "stalking " this site for a while and u guys know ur stuff . I've recently bought two rcf art 300a speakers . For some reason one will work well for about 10 mins or so then as a New song begins the speaker will drop in volume and sound really fuzzy for about 30 to 40 seconds then return to normal volume . Has this ever happened to anyone before ? Is it an easy fix ?I apologise if I've posted in the wrong place as I've just registered and am new .

[The Dude]

Sounds to me like a possible connection/solder joint issue. See if you can make it come and go by giving it a good whack. I suspect cabinet vibration is making and breaking a connection somewhere.

[Va joiner]

THANK YOU So much for your reply , The Dude . I took ur advice and a hand slap revealed no result but a gentle tap with a dead blow rubber mallet changed the sound instantly never would of thought to hit something hard to get a good result . I guess now I need to open the back and start looking for the bad joints ? Apart from visual inspections how else can I locate them ? I build cabinets and furniture ive repaired electric guitar bodies for mates who thought it couldnt be done . I have a 40watt electric solder iron and a multi meter . I also have cable ties and im not afraid to use them sorry for taking this long to reply I broke my tablet screen and had to pull out my emergency galaxy nexus . Using the net now is like typing something then having a cuppa tea before anything happens . Cheers \/

[Mick Bailey]

Firstly, check the speaker connections, they can come loose. There's a technique called 'Chopsticking' that's used to further diagnose intermittent problems. Basically, set up the amp safely so that it can be powered up with a low-level (comfortable volume) signal going through it. Then gently move, tap, probe or apply pressure to the circuit board, connectors and components to determine where the fault occurs. You may get lucky and locate the fault easily, or it could take a little time and patience. To do this you need an insulated probe, and a chopstick is ideal. I use the cream-coloured melamine ones.

The most likely point of failure is where there's a mechanical connection (such as a push-on spade terminal), or where there's a heavy, hot or high-current component. Or where there is mechanical stress, such as on the legs of a control potentiometer.

There are a few caveats to this;

1. Make sure you understand the dangers of working on powered equipment - transistor gear presents the same hazards as tube equipment. Keep your hands clear, especially around the power supply and mains inlet areas.

2. Don't poke things so hard you create a fault that wasn't there originally.

3. Concentrate on what you're doing and don't allow distractions. Especially cats. Mine, anyhow.

BTW,
I lived in Adelaide for a while, about 26 years ago. I wake up every day wishing I was still there. Getting out of bed, putting on my 'budgie smugglers' and taking a morning swim in the sea was a real delight. Champagne and chips in Glenelg of an evening, and a ride back on the old tram. Man, that was a great time. I had it in my hands and let it all slip away.

[Va joiner]

Thank you for ur technique . I'm more comfortable with a wooden tip drumstick I'll shave it to a finer tip to locate problem accurately . I'll give it a try tomorrow night . My cat won't come near me it's a feral I managed to feed as a kitten . Closest ive been is when I fell asleep on my office chair front door open and he /she walked past me . I woke up it jumped ten feet high .
Having been fortunate enough to receive two such informative helpful replies .
Thank you Mick Bailey
Thank you The Dude

Dear Mick Bailey The tram of which u talk about now goes down north terrace down port rd past coke company and ends infront of entertainment centre (corner port rd and adam st /Fitzroy tce opposite the Xmas display by west end brewery ) which may not have been built them yrs ago . I run a small joinery workshop in Brompton . This place (sa) is still as slow as south rd traffic oh that reminds me south rd now goes under port rd and grange rd . Well it will if they ever finish it .you did get to see the grand prix b4it was sold to Victoria . Hey funny truth . My first ever girlfriend's name was michelle bailey I was 13 or 14 she taught me to surf at west beach . Lol If i could ever b fortunate enough to afford a trip I would be in the UK tomorrow . Followed by the US the next week .

[Mick Bailey]

When we moved there our first location was just off Military Road, West Beach. Then we moved to Beverly, then to Croydon Park. We hardly ever saw anyone there - it was like humanity had been destroyed and we were the only survivors. Sounds like lots has changed. I wonder if you can still get a 'Pie Floater' outside the casino at night?