1998 Fender Vibro King ground issues and other problems

[jalexquijano]

Recently bought a used 1998 Fender Vibro King from Texas Guitar Center. Unfortunately it came with the tolex on the left corner torn and he wood underneath fractured. Asides from that i have a weird grounding issue which is always present and only goes away when you touch either the metal bridge of the guitar, the tuning pegs or any metal part or screw of the amp. I got fed up and took the amp to the tech and told him too look for any unsoldered or molested ground.

I would like to know if this issue can be solved or should i just return the amp to Guitar Center? This amp is custom made and point to point soldering no PCB. Any recommendations on changing the output transformer or any other upgrades?

[The Dude]

Check continuity of chassis to ground pin on the AC plug. Sounds like your chassis is not grounded.

[Leo_Gnardo]

changing the output transformer

If it ain't broke, don't "fix it." Square away your grounding problem first & foremost, then enjoy your amp.

[jalexquijano]

Check continuity of chassis to ground pin on the AC plug. Sounds like your chassis is not grounded.

this was checked and its not the problem. it only happens when i remove my hand from the strings, the amp or any métal pats

[J M Fahey]

Then the wall outlet ground is suspect.

As a side note:
* does amp hum with all controls set to 0?
* does it hum with all guitar controls set to 0?
* what happens when you unplug guitar cord from amplifier?


Get a long enough single conductor cable, wrap one end around some cold water tap, touch other end to chassis, what happens?

[Jazz P Bass]

Has a different guitar and cable been used in the check?

[jalexquijano]

Then the wall outlet ground is suspect.

As a side note:
* does amp hum with all controls set to 0?
* does it hum with all guitar controls set to 0?
* what happens when you unplug guitar cord from amplifier?


Get a long enough single conductor cable, wrap one end around some cold water tap, touch other end to chassis, what happens?

Believe me i just tested 4 of my tube amps with a telecaster which is single coil and a gibson 335 in the same outlet and none of them produce hum variation when i touch any metal part of the amp or the guitar. I even tested with a marshall 1959 hw which is point to point and there is variation. The problem must be in the amp grounding. The filter caps dont look as they have been swapped but i believe this is irrelevant.

[jalexquijano]

Then the wall outlet ground is suspect.

As a side note:
* does amp hum with all controls set to 0?
* does it hum with all guitar controls set to 0?
* what happens when you unplug guitar cord from amplifier?


Get a long enough single conductor cable, wrap one end around some cold water tap, touch other end to chassis, what happens?

Hum is reduced when i touch any metal part of the guitar or amp. I tested another model of this amp at a music store and it did not have this hand on hand off hum difference

[jalexquijano]

I checked each and every connection of the amp and do see anything disconnected.

[Jazz P Bass]

Take it back!

[nevetslab]

I tested another model of this amp at a music store and it did not have this hand on hand off hum difference

I've got to go along with Jazz P Bass on this one, as the other one at the music store didn't have this problem. I assume they will honor the complaint and allow return for the other one. Shame.....nice amps.