| Author |
Topic: Help with Fender Vibro Champ - vibrato not working.... |
Chuck Snider R.I.P.
From:
West Virginia, USA - Morgantown, WV
|
Posted 13 Oct 2009 2:44 pm |
|
I have what I believe is a '79 Fender Silverface Vibro Champ. I haven't had it long, and it seems to be working ok, except for the vibrato. I do have a an RCA jack given to me by Ken Fox to operate the vibrato on my Vibrosonic, and as far as I can tell from what little I can read in a schematic, it should also operate the vibrato on this little Vibro Champ. Are there any basic things I could check, and reseat (connectors or tubes) without burning my fingers off or getting knocked on my butt? I'm not too knowledgable of electronics, but i'm not afraid to check connectors or reseat stuff to see if it helps. However, I know some tube based electronics can bite!!! Would appreciate any help on this.
-Chuck
_________________
GFI U-12 Ultra Keyless, Carter Black U-12, both with Alumitones, and a sweet '70 Sho-Bud Permanent D-10, NV400 in Rick Johnson cabs, NV112, '73 Vibrosonic in Rick Johnson cabs, Hilton pedal, Steeler's Choice seat, Bessdang Gizmos from Dale Hansen, and a few other widgets and doodads.
I may not sound good, I just don't wanna sound bad. |
|
|
|
Ken Fox
From:
Nashville GA USA
|
Posted 13 Oct 2009 2:57 pm
|
|
Shorted RCA jack should start it. Could be the tube, could be one of the 3 caps in the circuit as well.
 |
|
|
|
Ben Jones
From:
Seattle, Washington, USA
|
Posted 13 Oct 2009 3:09 pm
|
|
the trem on my showman only works with the intensity between 8 and 10. It has the full range of intensity from non-existent to full on, but only between those two numbers. pardon the basic question and I am sure you have, but have you tried the trem with the intensity knob in all of its positions from 1 to 10 yet?
the trem on my vibro champ takes a moment to kick in also and oddly it will disappear if i turn the speed down below 2 no matter what the intensity.
neither of these trems get slow enough for me but Ive been too lazy to change those caps to slow it down
let us know what the problem was. |
|
|
|
Ken Fox
From:
Nashville GA USA
|
Posted 13 Oct 2009 3:25 pm
|
|
That is a different circuit than the Showman,
Ben, I have seen that before and it was a bad electrolytic cap in the circuit! Might be the same problem on yours.
 |
|
|
|
Chuck Snider R.I.P.
From:
West Virginia, USA - Morgantown, WV
|
Posted 13 Oct 2009 6:10 pm
|
|
Ken and Ben, thanks for the quick responses. Sounds like it might be best to track down a local tube mechanic. I can do soldering, but aside from just straight soldering, I don't know much (think zero) about electronic components. So, rather than smoking this little amp, I'll feel better running it into a shop. I will try the settings as you suggest Ben, and I'll give it a bit longer to warm up, maybe I was too quick to try it. If that makes a difference, I'll post an entry, otherwise figure it went to the doctor for Ken's suggested corrections.
Ken, if I lived closer I'd be dropping in and have you do your magic. By the way, that Vibrosonic you checked out for me sounds great!! I flushed out the pots with Funk-Out and that quieted down the idle noise.
Thanks guys!!!
-Chuck
_________________
GFI U-12 Ultra Keyless, Carter Black U-12, both with Alumitones, and a sweet '70 Sho-Bud Permanent D-10, NV400 in Rick Johnson cabs, NV112, '73 Vibrosonic in Rick Johnson cabs, Hilton pedal, Steeler's Choice seat, Bessdang Gizmos from Dale Hansen, and a few other widgets and doodads.
I may not sound good, I just don't wanna sound bad. |
|
|
|
Chuck Snider R.I.P.
From:
West Virginia, USA - Morgantown, WV
|
Posted 13 Oct 2009 6:26 pm
|
|
One thought just occurred to me after reading another post involving tube amps. If I understand correctly, the tube controling the vibrato is one of the 12AX7 tubes inside the little metal cans. Can I swap those two around to see if it changes anything? If the answer is yes, do I just merely pull them out and plug them in??? In other words, are there any settings for them or do you just plug them in and away you go? Or are they like I saw Ken doing at his shop and making some adjustments for some of the tubes?? I also could rob one of the 12AX7's from the Vibrosonic and try it just for diagnostic purposes?? Would that harm anything?
-Chuck
_________________
GFI U-12 Ultra Keyless, Carter Black U-12, both with Alumitones, and a sweet '70 Sho-Bud Permanent D-10, NV400 in Rick Johnson cabs, NV112, '73 Vibrosonic in Rick Johnson cabs, Hilton pedal, Steeler's Choice seat, Bessdang Gizmos from Dale Hansen, and a few other widgets and doodads.
I may not sound good, I just don't wanna sound bad. |
|
|
|
Raybob Bowman
From:
S. Lake Tahoe, CA, USA
|
Posted 13 Oct 2009 9:26 pm
|
|
| Chuck Snider wrote: |
One thought just occurred to me after reading another post involving tube amps. If I understand correctly, the tube controling the vibrato is one of the 12AX7 tubes inside the little metal cans. Can I swap those two around to see if it changes anything? If the answer is yes, do I just merely pull them out and plug them in??? In other words, are there any settings for them or do you just plug them in and away you go? Or are they like I saw Ken doing at his shop and making some adjustments for some of the tubes?? I also could rob one of the 12AX7's from the Vibrosonic and try it just for diagnostic purposes?? Would that harm anything?
-Chuck |
Swapping tubes is the easiest check you can do. Swap the 12AX7 with any other known good 12AX7. If you still have a problem, then you know it wasn't the tube.
_________________
Sierra U12 4+5 / 1933 Dobro / homemade Tele B-bender |
|
|
|
Chuck Snider R.I.P.
From:
West Virginia, USA - Morgantown, WV
|
Posted 14 Oct 2009 3:45 pm
|
|
Must be something else going on with this little guy. I swapped the 12AX7's around and it didn't make any difference at all. Gonna have to track down a good amp doc around here now.
-Chuck
_________________
GFI U-12 Ultra Keyless, Carter Black U-12, both with Alumitones, and a sweet '70 Sho-Bud Permanent D-10, NV400 in Rick Johnson cabs, NV112, '73 Vibrosonic in Rick Johnson cabs, Hilton pedal, Steeler's Choice seat, Bessdang Gizmos from Dale Hansen, and a few other widgets and doodads.
I may not sound good, I just don't wanna sound bad. |
|
|
|
Bob Bowden
From:
Vancouver, BC, Canada * R.I.P.
|
Posted 14 Oct 2009 6:45 pm
|
|
| I had a Vibro Champ several years ago with the same problem. Bought it cheap because the vibrato wasn't working. If I remember correctly, the vibrato started working after I replaced the electrolytic caps. |
|
|
|
