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Post subject: Vibro-King Problems
Posted: Wed Oct 17, 2007 11:27 am
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:?: I have 1998 Vibro-King & the amp starts breaking up at about 3 on the volume. is it the tranny or the tubes? any ideas anyone? Is this a common problem with the VK? I also have a ticking sound with the vibrato channel.


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Posted: Tue Oct 23, 2007 5:23 pm
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My Vibro King Custom also has the ticking noise you mention. It never really bothered me, because I dont notice it when I am playing. I only notice it when it is quiet and I stop playing. I alway thought that is just the nature of the beast on the vibrato channel.


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Post subject: Re: Vibro-King Problems
Posted: Wed Oct 24, 2007 9:20 am
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[quote="plockamy"]:?: I have 1998 Vibro-King & the amp starts breaking up at about 3 on the volume. is it the tranny or the tubes? any ideas anyone? Is this a common problem with the VK? I also have a ticking sound with the vibrato channel.[/quote]


Try another set of power tubes, maybe some JJ's.

The ticking sound can be cured. Here's how you'd do it on an older amp:

"Ticking" Vibrato
Fiberboard contamination: Dust, dirt, and junk can let the LFO signal leak into the audio path. Vacuum the dust and dirt away.

Solder blobs from eyelets touching insulating board: Sometimes excess solder drips out the bottom of an eyelet and can intermittetly contact the insulating board, can cause ticking. Remelt the eyelets and examine the board underneath for any blobs dripped down.

Funny ground on some SF Fenders; On one of the signal tubes, the cathode cap was placed on the tube socket, and wired to a ground lug on the vibrato cancel jack instead of across the resistor on the fiberboard. The vibrato shares this ground line, and can the vibrato current can cause audible ticking in the audio path. Rewire the cap to another ground or relocate it to the board.

Poor Signal wire layout: signal wires run too close to vibrato leads can pick up the LFO signal. Move them around and see if the ticking goes away.

Bad repair/replacement foot switch cable: the Fender footswitch cable is not two conductor; it's single conductor shielded, plus single conductor. The reverb wire is shielded, vibrato wire is not. This keeps vibrato out of reverb. If you retrofit with two conductor shielded, you get vibrato ticking onto reverb audio.

Sharp tick in vibrato oscillator: On neon/LDR Fenders, on the neon bulb side of the module there is a 10M to one side of bulb, 100K to the bulb; from the 10M straight across the board is the gnd point of the LDR. Put a 0.02 cap from 10M/bulb to the ground point; this works by filtering the output of the oscillator.


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Post subject: Re: Vibro-King Problems
Posted: Wed Oct 24, 2007 9:23 am
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plockamy wrote:
:?: I have 1998 Vibro-King & the amp starts breaking up at about 3 on the volume. is it the tranny or the tubes? any ideas anyone? Is this a common problem with the VK? I also have a ticking sound with the vibrato channel.


Also, get the bias checked on the amp. If it's set too high the amp will distort earlier. Always rebias after a retube.

Dave


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Posted: Tue Oct 30, 2007 5:22 pm
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Every Vibro King that I have ever seen ticks when the vibrato is on. I have had brand new ones and they also tick right out of the box. I have seen some mods on the net about it. Check around. I am sure someone has a fix. Thanks, Jeff.


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Posted: Wed Oct 31, 2007 11:50 am
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Those amps were designed to break up on the early side, hence the lack of negative feedback loop. At 4.5, my VK is screaminbg like a Marshall (which also has no NFB). Nature of the beast.

The ticking trem can be fixed by adjusting the distance of the opto sender and receiver. Bruce Zinky, who designed the VK for Fender, walked me through this fix on the phone.

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