It is currently Mon Mar 16, 2020 7:38 pm

All times are UTC - 7 hours



Post new topic Reply to topic  [ 7 posts ] 
Author Message
Post subject: '71 Twin Reverb-New Amp Day for me-questions..
Posted: Thu Oct 25, 2012 7:52 am
Offline
Roadie
Roadie
User avatar

Joined: Fri Sep 25, 2009 9:57 am
Posts: 291
Location: Eastern Iowa
I bought a '71 Twin Reverb loaded with JBL's the other day. It's basically been in storage as part of the guys collection for 20+ years, barely being used except to fire it up every so often to warm up the tubes. My question is-what, at this point needs to be looked at or checked out? The amp works great, sounds like a Twin should, and initialy has no issues. But I want to keep one step ahead of it, so what do I need to have done?

_________________
Life is like a sh*t sandwich. The more bread you have, the less sh*t you have to eat.


Top
Profile
Fender Play Winter Sale 2020
Post subject: Re: '71 Twin Reverb-New Amp Day for me-questions..
Posted: Thu Oct 25, 2012 8:15 am
Offline
Rock Star
Rock Star
User avatar

Joined: Sat Jul 03, 2010 2:18 pm
Posts: 6544
Ask around & find a good tech.

1.) Have him look at the MAIN electrolytic filter caps. Replace if necessary.

2.) Check BIAS POWER SUPPLY caps and voltage in this stage. Replace parts, if needed.

3.) Check the bypass caps. Replace if needed.

4.) Check the idle bias on the output tubes (6L6GCs). Adjust to specs.

5.) Check or test tubes for weak ones and noise. Replace, as needed.

6.) Put in a three-lead AC power line. With chassis grounded. Bypass any ground switch & eliminate the "death caps." If they are present in your amp.

7.) Have him or you or both of you test drive the amp is his shop. Before taking home.

Good luck with the amp! Any photos?

:D


Top
Profile
Post subject: Re: '71 Twin Reverb-New Amp Day for me-questions..
Posted: Thu Oct 25, 2012 8:36 am
Offline
Roadie
Roadie
User avatar

Joined: Fri Sep 25, 2009 9:57 am
Posts: 291
Location: Eastern Iowa
How do you post pics?

_________________
Life is like a sh*t sandwich. The more bread you have, the less sh*t you have to eat.


Top
Profile
Post subject: Re: '71 Twin Reverb-New Amp Day for me-questions..
Posted: Thu Oct 25, 2012 9:23 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Wed Mar 31, 2010 12:48 am
Posts: 26417
Location: Tombstone Territory
BMW2002Ti wrote:
Ask around & find a good tech.

1.) Have him look at the MAIN electrolytic filter caps. Replace if necessary.

2.) Check BIAS POWER SUPPLY caps and voltage in this stage. Replace parts, if needed.

3.) Check the bypass caps. Replace if needed.

4.) Check the idle bias on the output tubes (6L6GCs). Adjust to specs.

5.) Check or test tubes for weak ones and noise. Replace, as needed.

6.) Put in a three-lead AC power line. With chassis grounded. Bypass any ground switch & eliminate the "death caps." If they are present in your amp.

7.) Have him or you or both of you test drive the amp is his shop. Before taking home.


+1 on all counts

I'd simply add that the speakers should be pulled and inspected for any cone damage caused by rodents "dining" on the paper cones over the intervening years. Years ago I traded for a '66 Vibrolux Reverb that had been stored like that......long-term internment during which rats had feasted on the amp's Oxfords for about five years. They even ate the rubberized surrounds!

:mrgreen:

Arjay

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


Top
Profile
Post subject: Re: '71 Twin Reverb-New Amp Day for me-questions..
Posted: Thu Oct 25, 2012 9:58 am
Offline
Professional Musician
Professional Musician
User avatar

Joined: Sun Feb 15, 2009 3:52 pm
Posts: 2005
masterhacker wrote:
How do you post pics?


Look here:
viewtopic.php?f=2&t=52777

_________________
-T

"You can't spend what you ain't got, you can't lose what you ain't never had" ~ McKinley Morganfield


Top
Profile
Post subject: Re: '71 Twin Reverb-New Amp Day for me-questions..
Posted: Thu Oct 25, 2012 1:18 pm
Offline
Rock Star
Rock Star
User avatar

Joined: Sat Jul 03, 2010 2:18 pm
Posts: 6544
To demostrate...

Well, I use Photobucket (you need a "cloud" Net site to upload your photos, first). Then, scroll over the links below the photo to the IMG Code (for this site). And Copy and paste. So... this:

{IMG}http://i1191.photobucket.com/albums/z461/BMW2002Ti/Mary_zps83e1419f.jpg{/IMG}


Becomes this, with [img] replacing {img}




Image


Top
Profile
Post subject: Re: '71 Twin Reverb-New Amp Day for me-questions..
Posted: Fri Oct 26, 2012 1:35 pm
Offline
Professional Musician
Professional Musician
User avatar

Joined: Sun Feb 15, 2009 3:52 pm
Posts: 2005
BMW2002Ti wrote:
To demostrate...

Well, I use Photobucket (you need a "cloud" Net site to upload your photos, first). Then, scroll over the links below the photo to the IMG Code (for this site). And Copy and paste. So... this:

{IMG}http://i1191.photobucket.com/albums/z461/BMW2002Ti/Mary_zps83e1419f.jpg{/IMG}


Becomes this, with [img] replacing {img}





Image


Demo huh? :lol:

_________________
-T

"You can't spend what you ain't got, you can't lose what you ain't never had" ~ McKinley Morganfield


Top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 7 posts ] 

All times are UTC - 7 hours

Fender Play Winter Sale 2020

Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to: