Vibrato suddenly dead (M3). Where to begin?

[Guest]

Argh, I have to put my tonewheel experiments on hold because of a sudden crisis with my M3. Yesterday everything was sounding peachy. I decided to clean off some of the layers of dust &amp; grime back there, and now the vibrato doesn't work at all.</P>


When I engage the vibrato, the volume drops to a whisper (and there's no hint of vibrato). This happens on either manual, although the organ playsfine for whichever manual isnot using vibrato.Anothernew problem is that theorgan crackles like a bowl of Rice Crispies.</P>


I have no clue where to begin looking for trouble. I have a feeling it could be the amp, because aside from dusting &amp; swabbing, the onlymeddling I did wasto pull outthe tubes, clean the contacts and re-insert them ...but I suppose it's possible I damaged a tube in the process. I've tried re-cleaning and re-re-inserting them, but there's no change. All tubes seem to work--at least theyall glow.</P>


If I can get proof that the vibrato scanner is working, then the vibrato amp is definitely the problem. But where to I tap in to find out? [*-)]</P>

[geoelectro]

Re: Vibrato suddenly dead (M3). Where to begin?



There are two 6AU6a tubes in your amp just to the right of the 12AX7a tube that is near the center of the amp. One 6AU6a tube is for vibrato while the other is the straight channel. You can swap them with each other to see if it's a tube problem. If the problem moves to the non-vibrato making the vibrato work after swapping, you have a bad tube.</p>

George
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[Guest]

Re: Vibrato suddenly dead (M3). Where to begin?



geo, once again that was the perfect diagnosis! I swapped the tubes, and suddenly vibrato worked &amp; clean went quiet. Now I just need to pick up a new 6AU6a and I'll be back in action. They seem to be pretty inexpensive &amp; easy to find on ebay. MUCHOS GRACIAS!!</P>


P.S. Can you or anyone else recommend a good brand of 6AU6a? I found a seller who has an assorted lot, and he's asking me which I prefer. Who manufactured the original "Hammond" branded tubes?</P>