| Author | Message | ||
     Chris Nevins (rhythmseeker) Username: rhythmseeker Registered: 03-2012 |
Pulled this cool amp out of someone's trash!!! After what looked like a rabbit had made a nest inside the cab, I replaced the chewed tolex and grillcloth, and reconed the massive EV 12L. Thankfully the chassis was immaculte with zero rust anywhere. Threw in some NOS 6L6GC's and she fired up okay, but static white noise plagues it. It's only in main inputs, but if I plug into 100mv or 3v line-in inputs, she's quiet as can be. Does this indicate a pre amp issue? I recently replaced the two monster 100MFD/450v caps under the 'doghouse', hoping this would fix the noise, but to no avail. I would really like to use this amp as more than a paperweight, but noise is just to much. I have done amp work on 100% tube amps but, this SS stuff is scary. I don't want to ruin this jem. Thanks for any help.}}} | ||
| Lars Verholt (lmv) Username: lmv Registered: 11-2009 |
Hi Chris, If we assume that the noise is originating in a stage preceeding the 100mV insert point, the level of noise should be controlled by the gain control as well as the master volume. Pull IC-1 (front end) and IC-5 (reverb drive/recovery). Insert IC-5 in IC-1's place and fire up. You will not have any reverb at this point but if the noise is gone and you have a good sounding straight signal, you know that the original IC-1 is bad. This is purdy much like troubleshooting the 'frying bacon' sound in a Deluxe Reverb - swap two 12AX7 tubes and see if that makes a difference. PS - nice score! Hope this helps, -Lars Verholt | ||
| Jeremy Shaw (jemshaw) Username: jemshaw Registered: 09-2006 |
Yes nice score! pictures please (which is a bit cheeky as I havent figured out how to do that yet. | ||
| Chris Nevins (rhythmseeker) Username: rhythmseeker Registered: 03-2012 |
Thanks for the kudos! I consider myself lucky to have the opportunity to rescue her. Okay, I located the target ICs and am going to see what happens tomorrow. Keeping fingers crossed. | ||
| Chris Nevins (rhythmseeker) Username: rhythmseeker Registered: 03-2012 |
Made the switch and she plays like a champ! Way too easy, too! Now just need to order a new IC. I noticed there are many choices, differentiated by a suffix like: "CN", "ACN", "AMH" Besides the price, what's the difference? Should I order enough to replace all seven ICs, or maintain the "if it ain't broke, don't fix it" rule? Thanks again! | ||
| Lars Verholt (lmv) Username: lmv Registered: 11-2009 |
Hi Chris, if you ask me, it's not that critical which one you get. Make sure it's the correct package (DIP). Sure, order a couple of extra ones just so you can replace if another one goes noisy. Cheers, Lars Verholt www.captain-foldback.com |