Crackling Twin??

Redd Volkaert · December 13th, 2003, 12:03 PM

When I turn on my twin, after about ten minutes it starts crackling and frying quite loud. Even with the volume off.

If I put it on stand by for however long, when I turn it back on it still lasts (the crackling) for five minutes or so.

Almost every gig, WHY???? :(

I've wiggled every tube, sprayed sockets, . . . :?

Thanx in advance, Anybody?? Redd

idylldon · December 13th, 2003, 12:34 PM

Redd,

Because it seems temperature related (starts when the amp heats up a bit), my first guess would be the preamp tube plate load resistors. Unless I'm not remembering right, I think you've said your Twin is a '65. If so, and if it hasn't had the plate load resistors replaced, that would be the first place I'd look. The originals are 1/2-watt carbon comp, and they take a bit of a beating over time in that application. The common replacements are usually metal film. Some folks who think carbon comps make a tone difference in this area of the circuit usually use 1-watt carbon comps (or films) because they'll remain more stable in the application.

I'd also pull the chassis to check for bad solder joints, though my guess is that this would be far less temperature dependent. I've seen quite a few older Fender circuit boards flex enough to break the solder line around the component lead. You have to look close to see it. Heating and reflowing the joint fixes the problem.

You could pull the phase inverter tube, the small tube right next to the power tubes, which would tell you if the sound is originating in the preamp or power amp section of the amp. If the crackling goes away, then the problem is in the preamp section.

You probably know all this already, but I thought I'd mention it just in case you didn't.

Cheers,
--
Don

BTW, if you lived in So. Cal I'd fix that amp for you for free. OK, you'd have to show me a few licks! ;-)

Cam · December 13th, 2003, 01:16 PM

http://www.hoffmanamps.com/fenderservice6.htm

Big Cookie · December 13th, 2003, 04:12 PM

I'll line it out for you.

Redd Volkaert · December 14th, 2003, 12:01 AM

Thanx so much for the tips, I'll check it out & see.

Baard · December 15th, 2003, 05:36 AM

with my old super reverb. cracle snap pop zizzle.... I changed all the tubes, and it was gone....

Baard

dp2me · December 19th, 2003, 04:18 AM

Hi Redd - funny - I have a 65 Twin doing the same damn thing right now....maybe it's the weather...

I used to live in Austin forever (now in Cali)
Go meet Jon Bessent at Walter Hutchins Musical Exchange. He's a very wise Fender amp guy - and a great guy/character. He's the engineer behind Austone pedals (builds for Mr. Gibbons et al.)

Anyhow, Jon knows his **** and you probably know him anyhow - He can tear apart any Fender like it's nobody's biz... Buzz him at 467-9600

I used to check you out occasionally on Sunday at the Continental. Holy cripes. You smoked and twisted it all up. Thanks for those moments~

-Dave in Cali (Ex-Austinite)

dp2me · December 19th, 2003, 04:26 AM

now, just when did the word s-h-i-t become a bad word??

-Dave

dp2me · December 19th, 2003, 04:34 AM

One last comment Redd-

If you haven't been there, Walter Hutchins Musical Exchange is in Hyde Park on North Loop. Jon has a workspace in the shop.

PS - I would recommend Jon to anyone in the area. He did a killer job diagnosing my Twin and rebuilding a silver Princeton R. for me....

December 13th, 2003, 12:03 PM	#1 (permalink)
Redd Volkaert Tele-Meister Join Date: Mar 2003 Location: Austin Texas Posts: 441	Crackling Twin?? When I turn on my twin, after about ten minutes it starts crackling and frying quite loud. Even with the volume off. If I put it on stand by for however long, when I turn it back on it still lasts (the crackling) for five minutes or so. Almost every gig, WHY???? :( I've wiggled every tube, sprayed sockets, . . . :? Thanx in advance, Anybody?? Redd

December 13th, 2003, 01:16 PM	#3 (permalink)
Cam Tele-Afflicted Join Date: Mar 2003 Location: Snow Piles Alberta Canada Posts: 1,022 7 Photos	See if this page helps.... http://www.hoffmanamps.com/fenderservice6.htm __________________ Relic Schmelic! Play the darn thing! Wipe it down after and put it in it's case!

December 13th, 2003, 04:12 PM	#4 (permalink)
Big Cookie Banned Tele-Holic Join Date: Mar 2003 Location: Ennis, Texas Posts: 693	Redd call me I'll line it out for you.

December 14th, 2003, 12:01 AM	#5 (permalink)
Redd Volkaert Tele-Meister Join Date: Mar 2003 Location: Austin Texas Posts: 441	Thanx Thanx so much for the tips, I'll check it out & see.

December 15th, 2003, 05:36 AM	#6 (permalink)
Baard Tele-Holic Join Date: Mar 2003 Location: Denmark Posts: 668	Well I had the same problem with my old super reverb. cracle snap pop zizzle.... I changed all the tubes, and it was gone.... Baard __________________ All truth passes through three stages. First, it is ridiculed. Second, it is violently opposed. Third, it is accepted as being self-evident.

December 13th, 2003, 12:34 PM	#2 (permalink)
idylldon Tele-Meister Join Date: Mar 2003 Location: Idyllwild, CA Posts: 102	Redd, Because it seems temperature related (starts when the amp heats up a bit), my first guess would be the preamp tube plate load resistors. Unless I'm not remembering right, I think you've said your Twin is a '65. If so, and if it hasn't had the plate load resistors replaced, that would be the first place I'd look. The originals are 1/2-watt carbon comp, and they take a bit of a beating over time in that application. The common replacements are usually metal film. Some folks who think carbon comps make a tone difference in this area of the circuit usually use 1-watt carbon comps (or films) because they'll remain more stable in the application. I'd also pull the chassis to check for bad solder joints, though my guess is that this would be far less temperature dependent. I've seen quite a few older Fender circuit boards flex enough to break the solder line around the component lead. You have to look close to see it. Heating and reflowing the joint fixes the problem. You could pull the phase inverter tube, the small tube right next to the power tubes, which would tell you if the sound is originating in the preamp or power amp section of the amp. If the crackling goes away, then the problem is in the preamp section. You probably know all this already, but I thought I'd mention it just in case you didn't. Cheers, -- Don BTW, if you lived in So. Cal I'd fix that amp for you for free. OK, you'd have to show me a few licks! ;-)

December 19th, 2003, 04:18 AM	#7 (permalink)
dp2me TDPRI Member Join Date: Nov 2003 Location: san rafael, ca Posts: 13	same here Hi Redd - funny - I have a 65 Twin doing the same damn thing right now....maybe it's the weather... I used to live in Austin forever (now in Cali) Go meet Jon Bessent at Walter Hutchins Musical Exchange. He's a very wise Fender amp guy - and a great guy/character. He's the engineer behind Austone pedals (builds for Mr. Gibbons et al.) Anyhow, Jon knows his **** and you probably know him anyhow - He can tear apart any Fender like it's nobody's biz... Buzz him at 467-9600 I used to check you out occasionally on Sunday at the Continental. Holy cripes. You smoked and twisted it all up. Thanks for those moments~ -Dave in Cali (Ex-Austinite)

December 19th, 2003, 04:26 AM	#8 (permalink)
dp2me TDPRI Member Join Date: Nov 2003 Location: san rafael, ca Posts: 13	censored?? now, just when did the word s-h-i-t become a bad word?? -Dave

December 19th, 2003, 04:34 AM	#9 (permalink)
dp2me TDPRI Member Join Date: Nov 2003 Location: san rafael, ca Posts: 13	p.s One last comment Redd- If you haven't been there, Walter Hutchins Musical Exchange is in Hyde Park on North Loop. Jon has a workspace in the shop. PS - I would recommend Jon to anyone in the area. He did a killer job diagnosing my Twin and rebuilding a silver Princeton R. for me....