Amp got da buzz

[Roosterman]

Need a little help here fellas...

Iv just taken an amp in to fix for a friend, but before I tear it apart, I just wanna check my thinking - and show yas some pics of this little beauty! lol
By the way, these arnt the pics of my mates, but its exactly the same... and nearly as clean!

Its a nice little WEM Westminster combo which he bought brand new in the late 60s / early 70s. Its in relatively good condition, but crackles and pops no end. As far as I can tell (from the stamp on the big red cap), it was last checked in 1973!!

Iv tried spraying switch cleaner into the pots and its no different, so Im thinking next step is replace the pots entirely. Trouble is, I cant tell what size the pots are... they dont seem to be marked.

Any tips on rebuilding the pots?

[Roosterman]

Pity it aint mine.... yet! lol

Im not sure the guy will want to spend the money on it as when its done, its still barely worth anything!

Thanks for the info on the tubes too... I got a lot to learn in this department.

LJ said:

That is one cool amp. I love it. and so clean

[Roosterman]

Well, chasnge of plan - its now in for the full rebuild! lol

Iv ordered a new set of tubes, then Il replace the caps if need be.

Il keep ya posted :o)

[juju]

well at least that will eliminate the valves been duff - if you have checked and cleaned the pots then that can only point to the Caps -as i mentioned on the phone to you last night i have read that the old style electrolitic Capacitors are good for around 20-30 years in constant use this lessens when they have been stored - theres not that much to go wrong in a valve amp besides valves , pots , and caps all of which are pretty cheap to replace
good luck - hey maybe the guy may just give up in the end and tell you to dump it for him - if so i know a good dump here in Sheffield where you can deposit it :-) hehehehe!!
juju.

[smojo]

Ben, sounds like it could be tubes arc-ing but could also be a capacitor breaking down if it's 30-40 years old. Hard to diagnose though. Some quite high voltges in these tube amps so be very careful.

[Roosterman]

You're too kind Juju, thanks! :o)

Im seriously getting to like all this valve stuff... those kits are looking mighty tempting!

juju said:

well at least that will eliminate the valves been duff - if you have checked and cleaned the pots then that can only point to the Caps -as i mentioned on the phone to you last night i have read that the old style electrolitic Capacitors are good for around 20-30 years in constant use this lessens when they have been stored - theres not that much to go wrong in a valve amp besides valves , pots , and caps all of which are pretty cheap to replace
good luck - hey maybe the guy may just give up in the end and tell you to dump it for him - if so i know a good dump here in Sheffield where you can deposit it :-) hehehehe!!
juju.

[Roosterman]

Safety gear: pair of yellow marigolds, welly boots, sunglasses... I think Im all set! ;o)

smojo said:

Ben, sounds like it could be tubes arc-ing but could also be a capacitor breaking down if it's 30-40 years old. Hard to diagnose though. Some quite high voltges in these tube amps so be very careful.

[juju]

Yep i think you got it all coverd lol!
juju

Roosterman said:

Safety gear: pair of yellow marigolds, welly boots, sunglasses... I think Im all set! ;o)

[DeDa Badaddy (AndyE)]

And keep one hand behind your back - if you get a jolt, it might not kill you.

Roosterman said:

Safety gear: pair of yellow marigolds, welly boots, sunglasses... I think Im all set! ;o)

smojo said:

Ben, sounds like it could be tubes arc-ing but could also be a capacitor breaking down if it's 30-40 years old. Hard to diagnose though. Some quite high voltges in these tube amps so be very careful.

[ChickenboneJohn]

I'm no amp expert, but my thought was possibly capacitors being on the way out, they are often made with some pretty unstable stuff like waxed paper which doesn't hold up well after a few decades - I haven't got a clue as to how you check this.

Wouldn't have thought it was the pots - they will either work or not, or just sound scratchy as you turn them, I don't think they will be responsible for that sort of background noise you are describing. ...super-cool amp tho, love those old WEMs.

[Roosterman]

Cool, thanks for the tip Andy ;o)

Iv also been led to believe that one can reduce the risk of shock by crossing the fingers and shutting the eyes tightly. Anyone know if this is true?

DeDa Badaddy (AndyE) said:

And keep one hand behind your back - if you get a jolt, it might not kill you.

Roosterman said:

Safety gear: pair of yellow marigolds, welly boots, sunglasses... I think Im all set! ;o)

smojo said:

Ben, sounds like it could be tubes arc-ing but could also be a capacitor breaking down if it's 30-40 years old. Hard to diagnose though. Some quite high voltges in these tube amps so be very careful.

[Roosterman]

Yup, its all new to me too John, but as Juju said, there aint much in them to go wrong. The tubes should be here today - if that doesnt sort it, Il swap the caps.

ChickenboneJohn said:

I'm no amp expert, but my thought was possibly capacitors being on the way out, they are often made with some pretty unstable stuff like waxed paper which doesn't hold up well after a few decades - I haven't got a clue as to how you check this.

Wouldn't have thought it was the pots - they will either work or not, or just sound scratchy as you turn them, I don't think they will be responsible for that sort of background noise you are describing. ...super-cool amp tho, love those old WEMs.

[juju]

Yep i know i'm all heart - i'm far too Kind to you lot :-)
juju.

Roosterman said:

You're too kind Juju, thanks! :o)

Im seriously getting to like all this valve stuff... those kits are looking mighty tempting!

juju said:

well at least that will eliminate the valves been duff - if you have checked and cleaned the pots then that can only point to the Caps -as i mentioned on the phone to you last night i have read that the old style electrolitic Capacitors are good for around 20-30 years in constant use this lessens when they have been stored - theres not that much to go wrong in a valve amp besides valves , pots , and caps all of which are pretty cheap to replace
good luck - hey maybe the guy may just give up in the end and tell you to dump it for him - if so i know a good dump here in Sheffield where you can deposit it :-) hehehehe!!
juju.