Need help with my JCM900 fast! - Jemsite
Tech: Setup, Repairs and Mods Guitar workbench discussion such as setup, repairs, mods, installing new parts and more.

 
LinkBack Thread Tools Display Modes
post #1 of 9 (permalink) Old 02-01-2006, 04:15 PM Thread Starter
 
Join Date: Mar 2005
Posts: 88
Need help with my JCM900 fast!

Mjello! I am doing a concert friday, and now my JCM 900 model 2100 is giving me a headache! It starts to fade out some times, I checked the cabels, and it is not them. What is wrong, and how do I solve the problem
Speedica is offline  
Sponsored Links
Advertisement
 
post #2 of 9 (permalink) Old 02-01-2006, 10:24 PM
 
Join Date: Jan 2005
Location: IA, USA
Posts: 1,008
Re: Need help with my JCM900 fast!

I believe when it starts fading it can mean the tubes are wearing out, but I could be wrong, somebody else correct me on this if so
nightfiend14 is offline  
post #3 of 9 (permalink) Old 02-01-2006, 11:05 PM
 
Join Date: Mar 2005
Posts: 442
Re: Need help with my JCM900 fast!

when ever i have volume probems with a tube amp the first thing i do is check the tubes, but im no pro on this so i cant give a definate answer, how long have the current tubes been in the head?
guitardevil2005 is offline  
post #4 of 9 (permalink) Old 02-01-2006, 11:13 PM
 
Join Date: Apr 2005
Posts: 1,183
Re: Need help with my JCM900 fast!

Check your amp, i had the same problem, also check the wiring inside the guitar it might've got whirled up.
carlos grijalva is offline  
post #5 of 9 (permalink) Old 02-02-2006, 12:47 PM Thread Starter
 
Join Date: Mar 2005
Posts: 88
Re: Need help with my JCM900 fast!

It's not my other gear, it's definitely the amp. I bought the amp used, but he said he just changed the tubes, and they look new to me. But maybe he lied to get it sold :P

I checked the wireing, and it's okay... So it's the tubes or what?
Speedica is offline  
post #6 of 9 (permalink) Old 02-02-2006, 12:55 PM
 
Join Date: Mar 2001
Location: Va Beach, VA
Posts: 1,416
Re: Need help with my JCM900 fast!

Get new tubes, preamp and power amp. Change them one at a time and test after each change. It might be a tube, it might be a socket. It's most likely a power amp tube issue if it is a tube issue at all, but preamp tubes are cheap so just cover all the bases. Problem solving is process of elimination so it's important to only change one thing at a time, check it, then change something else, check it...and so on.

If you've got a gig, even if you get this "fixed" I'd rent or borrow a backup just in case.
Gresh is offline  
post #7 of 9 (permalink) Old 02-02-2006, 05:05 PM
 
Join Date: Dec 2005
Location: Oxfordshire
Posts: 2,244
Re: Need help with my JCM900 fast!

Tubes!
Ant1981 is offline  
post #8 of 9 (permalink) Old 02-02-2006, 07:53 PM
rgr
 
Join Date: Dec 2000
Location: Longmont, Colorado
Posts: 1,882
Re: Need help with my JCM900 fast!

It would suck to spend the $ for a full set of tubes and that not be the problem, it's probably worth taking to a tech ASAP, it could be a loose tube socket, bad cap, who knows.

A backup set of tubes is never a bad idea, but no guarantee that it will fix this problem.
rgr is offline  
post #9 of 9 (permalink) Old 02-02-2006, 08:04 PM
 
Join Date: Sep 2001
Location: Dorset, UK
Posts: 330
Re: Need help with my JCM900 fast!

Take it to a tech and get it checked out. Just like your car needs to go into the shop for maintenance once in a while, tube amps need the same TLC.

You can buy new tubes and swap them out yourself by all means but the amp will most probably need to be rebiased for the new tubes slightly to get the amp sounding tip top. This is definitely a job for a specialist. This link describes the need for proper biasing better than i can:

http://www.watfordvalves.com/pdfs/guitarv10n3p120.pdf

Scroll down to page 3 where there is a whole section on biasing.

Good luck!
wallopwallop is offline  
Reply

Tags
power amp , preamp tube , tube amp , tube amps

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Jemsite forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address

IMPORTANT: You will be required to activate your account so please ensure that your email address is correct.

If you do not receive your activation check your spam folder before using the CONTACT US form (at the bottom right of each page).



Email Address:
OR

Log-in











Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
JCM900 NNS Gear, Equipment, Recording & Off Topic 27 01-10-2007 02:44 PM
Fs Jcm900 maliciousteve Classified Ads: Guitars and Gear 3 10-06-2005 07:20 PM
JCM900 or DSL100? Chud Gear, Equipment, Recording & Off Topic 35 09-07-2005 08:36 PM
FT:Marshall JCM900 MALAM Classified Ads: Guitars and Gear 0 07-14-2005 01:16 PM
Fast fret, going no where fast woodros Tech: Setup, Repairs and Mods 6 09-24-2002 11:09 PM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome