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The last of the five Fender Deluxe Reverbs I've had in the shop....this one was noted to having a Hi Pitch Squeal when turned on, switching out of Standby. As luck would have it, I was unable to repeat the problem on the bench. Went thru the usual motions to try and induce it with no luck. Last time this same amp had the problem, it would squeal as soon as you turned it on (last October). I didn't find it then either. Though then, I did notice Vibrato Ch V2 preamp tube was vibration sensitive. I've tapped on all of the tubes, both with and without the shields installed. Tapped on the power tubes, rectifier tube, hammered on the cabinet, hammered on the reverb tank, Reverb level turned up.
I searched thru my Service Notes database, setting the search for Fender, Model, Asset #, and then scrolled thru the 12 years of records to find each and every Fender amp that has had this issue. Most I found were related to the Reverb circuit....a Vibrolux Reverb last year had too much Reverb return gain, and lowered that by 10dB to cure it, still having plenty of gain for the tank. One other amp that had loud squeal was a SF Twin Reverb, whose power tube sockets were all loose, one not even showing the tube lit up. Had to re-tension the tube socket contacts, then the squeal problem was gone.
So, while I again didn't find the cause, I did find this is a repeat offender, and will hopefully find the issue. For now, it's been put back into play. Nice to have that ever-growing data base on every amp and project that has come thru the shop!
Anyone find this hi-pitch squeal problem before?
I searched thru my Service Notes database, setting the search for Fender, Model, Asset #, and then scrolled thru the 12 years of records to find each and every Fender amp that has had this issue. Most I found were related to the Reverb circuit....a Vibrolux Reverb last year had too much Reverb return gain, and lowered that by 10dB to cure it, still having plenty of gain for the tank. One other amp that had loud squeal was a SF Twin Reverb, whose power tube sockets were all loose, one not even showing the tube lit up. Had to re-tension the tube socket contacts, then the squeal problem was gone.
So, while I again didn't find the cause, I did find this is a repeat offender, and will hopefully find the issue. For now, it's been put back into play. Nice to have that ever-growing data base on every amp and project that has come thru the shop!
Anyone find this hi-pitch squeal problem before?
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