Featured Post

Echoluxe: Repairs Restorations Lessons Guitars

For Lesson Info Click Here For Repair Info Click Here

Tuesday, March 7, 2017

Ampeg SVT CL Blues

Ampeg SVT's could be the greatest bass amp of all-time.  Ampeg SVT-CL's could also be the most difficult and dangerous amp to service of all-time.  It's been well documented online, notably in this four page, 28 picture epic by: Bustedgear.com
SVT-VR (Vintage Reissue)
SVT-CL (Classic Reissue)
Here's a message I sent to famous touring band:

"It had at least six different problems, notably some bad power tubes, screen grid resistors and cathode power resistors.  There's no telling what took what down, it's the chicken or the egg really.  I'm sure it got worse and worse, eventually the amp was working against itself.

I know I ramble on about these.  They're a great bass amp.  The best.  But the way they're constructed is almost impossible to safely work on.  You have to dismantle and un-pancake pc boards to work on or replace components, removing the power tubes and all attaching sockets.  Once you get a feel for the damage you have to reassemble to test, repeat disassemble to repair, etc. ad nauseam.  Flipping around an 85 lb. amp is not easy, nor safe when there's close to 700 volts DC.  If anything touches any metal it's fireworks...sometimes the nuts pop off the chassis just when you've put it back together, you have to pull it apart to retrieve and start over...it's challenging.

To better appreciate/respect the amp and what goes into it take 2 minutes to browse these pics (this is not us):  http://www.bustedgear.com/repair_Ampeg_svt_classic_shutoff.html

Some guys prop it up with wood to test it, some stand it upright, it's just crazy.  So basically I got the new tubes in, it was still in fault mode.  There were some burnt components on the power tube board I replaced, still not right.  On the board (under the power tube board) there were some off voltages, isolated and replaced key resistors.  Things are lining up now.  I've had it on, on the bench, and it's been in the green for the last 2 hours.  Btw L., it's been on the bench since Tuesday when we hoisted it up there, I have not been able to move it nor complete any other jobs since."
SVT CL PC Board 1
SVT CL PC Board 3 (Board 2 Underneath)
SVT VR all on one board