Matchless Clubman trouble (hum)

[jezzbo]

Hello everybody,

A friend of mine has trouble with his matchless clubman.
There was no sound. When looking at the tubes, i noticed that the gz34 rectifier didn't light up.
When i gently rocked the tube, there was contact. So i guessed there must be something wrong with the tubesocket or the rectifier tube.
So i changed both.

But something is yet not right.
When the amp is switched on, the rectifier lights up.
So far so good.
But when i switch the standby switch on there is a loud hum and no signal.

The voltage meassured on the pt secondary windings are:
5.32v for heater rectifier.

2x 361v for b+

6.3v for heaters

So that seems fine for me

The 361v wires (yellow) are connected on pin 4 and 6 of the rectifier socket.
The rectifier 5v wires are conncected to pins 8 and 2 of the rectifier socket.
From pin 8 there goes a wire to the first elko. (b+)

Could it be that i have to reverse the rectifier heaterwires?
(so switching 0v and 5v) or could there be an other problem?

The only thing i did was replace the rectifier tube socket and rectifier tube.

Thank you for your help.


[/code]

[chocopower]

From pin 8 there goes a wire to the first elko. (b+)

What DC voltage do you have there?

[martin manning]

The rectifier is wired correctly, and the 5V filament supply polarity does not matter. Have the filter capacitors been replaced?

[jezzbo]

From pin 8 there goes a wire to the first elko. (b+)

What DC voltage do you have there?

somewhere arround 420V (i'm not sure, I did meassure but didn't wrote it down. I have to meassure again)

[jezzbo]

The rectifier is wired correctly, and the 5V filament supply polarity does not matter. Have the filter capacitors been replaced?

The filtercaps was something I thought about too.
But I didn't replace any.


Thank you for your replies.

[Aaron Howell]

Just ran into a similar problem with a Matchless 3015. The problem turned out to be a faulty socket. The center of the socket was too large in diameter. It allowed the recto tube to be inserted in any orientation. A new socket solved the problem. Here's a pic of the defective socket with the tube improperly inserted.

[IMG:799:596]http://i46.photobucket.com/albums/f133/ ... b80381.jpg[/img]

[Luthierwnc]

To echo some comments above, the first thing I'd do is retension the sockets. The metal sleeves in the socket holes will loosen over time and get some play in the contact. They can also corrode and reduce the surface area hitting the pins. I've used a Dremel with a really small bottle brush but haven't seen one like it in the accessory stand lately. If not, just roll up a piece of wet-or-dry 400 grit sand paper and pass it back and forth a couple times. Retensioning is just a matter of prying the contacts closer together. If the sockets are really shot, replace them.

One thing to watch for. Sometimes sockets corrode because they have been exposed to leakage from other components. Look for fried caps in the area if you find what looks like congealed oil. FWIW, Skip