In article <4isb5r$fa--(at)--enator-bedfellow.MIT.EDU>, theodri--(at)--(Theodric
Young) wrote:

> I just got a blackface 70 Watt Fender Pro Reverb (1981 I believe). When
> I checked it out at the store, there was a ticking sound in the output
> that could be heard when the master volume knob was turned up....
>
> At first, the guys at the store said they would fix that under
> warranty. However, after consulting with their amp repair guy, they
> now say that that ticking is present in all of those particular amps.
> The problem, they say is that the plate wire is too colse to the grid
> wire on one of the tubes. They can fix it, supposedly, by installing
> a capacitor somewhere, although it comes under the category of a
> modification, not a repair, so I'd have to pay for their labor.
>
> This ticking really isn't all that loud and I could certainly live
> with it, but I'm curious as to whether or not anyone else has ever
> come across this, and if so, how they fixed it.
>
> Also, if anyone knows where I could get ahold of schematics for this
> amp, I'd greatly appreciate it.
>
> Thanks in advance.
>
> -Theodric Young
>

The ticking is a common problem. It can be often be reduced by redressing
the wiring. Silverface amps are usually worse than blackface which had
neater wiring.

The ticking can usually be eliminated by installing a 0.01 µF cap from one
side of the LDR assembly to ground. The cap goes on the side that is
connected to the 10 Meg resistor. This fix is described in Weber's book
which also includes schematics (Along with his personal opinions on
everything. The reader needs to sort out the facts from the hype). If you
are not comfortable working on your own amp then any good tech should know
about this fix.

IMHO the store should have fixed this under warranty as promised. It's no
big deal. I think Fender even put out a service bulletin describing the
fix.

Good Luck,
Tom Phillips

From Dr.Distortio--(at)--bs.mhv.net Sat Mar 23 15:48:22 CST 1996
Article: 11792 of alt.guitar.amps
From: Dr.Distortio--(at)--bs.mhv.net (Dr Distortion)
Newsgroups: alt.guitar.amps
Subject: Re: vibrato fix for Fender Pro Reverb
Date: 22 Mar 1996 20:50:29 GMT
Organization: MHVNet, the Mid Hudson Valley's Internet connection
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Theodoric,
That ticking you hear is a common problem. It's caused either by HF hash
>from the neon bulb in the tremolo optocoupler, hash from the oscillator
circuit itself, or a combination of both. The leads that carry the preamp
signal to the input of the phase inverter are perilously close to the
trem circuit, so unwanted coupling occurs easily. A good tech can improve
the situation substantially by cleaning up the lead dress around the
tremolo and phase inverter circuits. Also, that .02 cap you often see
placed across the neon in the silverface amps can make a big difference.
The cap is of a large enough value to help shunt HF hash, but small
enough that it doesn't form an accidental relaxation oscillator with the
neon :)
At any rate, make sure your tech has experience with old Fenders. This
is a common problem which an experienced tech can rectify without much
trouble in most cases. Guys who don't have a good grasp of these circuits
are likely to be left scratching their heads for hours, on the other hand.

Index:

1974 prices	3 Spring Reverb Tanks	3 Wire Cord installation	5R4 not enough current
5V4 in BF Deluxe	6550s in Super	68 Princeton Rectifier	68 Super Reverb
6L6 in Champ Again	6L6 in Deluxe LV	6L6 in Deluxe Reverb	6SC7 to 12AX7
6V6 In 6L6 Amp Test	6V6 in Showman Test	6V6s in Super	AA vs AB 763
AA763 vs AB763	Alternative Switches	Bad Fender Mods	Bandmaster Cathode Bias
Bassman 10 info	Bassman Head Running 2ohms	Beef Up Tweed Champ	Birth of Fender Reverb
Blackface Cabinet Dates	Blackface Pro	Blame UL	Blues Deluxe review
Brown Bassman Transformers	Brownface Trem Pulse	Brownface Tremolux Cabinets	CBS Deluxe Reverb Changes
Champ 8ohms	Champ problems	Champ speakers	Champ Transformers
Choke Specs	Clean Ckt Board	Concert Head Footswitch	Dead Amp Checkout
Deluxe Cathode Bias Mod	Deluxe reissue vs original	Deluxe Tweed vs BF	Design Eras
Detailed AB568 test	diy	Dr Z Harp Amp Mods	Early Blackfacing
Ed Jahns Xformers	Eyelet Board Problems	Faceplate Restoration	Factory Mistakes
Fender 6V6 Overvoltage	Fender AA568 circuit	Fender Alternative Footswitches	Fender Amp Covering
Fender Amp Dating	Fender amp tremolo	Fender Amp Tremolos	Fender bad Supers
Fender BF Bassman mods	Fender BF SF changes	Fender Bias Pot Failures	Fender Bias Schemes
Fender Blackface	Fender Blues Deluxe Settings	Fender brownface topology	Fender Cap Replacements
Fender Channel Coupling Caps	Fender Combo Reverb trick	Fender Concert Reissue	Fender Concert Tremolo
Fender Correct Tubes	Fender coupling caps	Fender decrease reverb mix	Fender Deluxe Power Trans
Fender Deluxe reissue	Fender diodes	Fender Ext Spkr Jack	Fender Grill Cloth
Fender ID circuits	Fender Input Jacks	Fender Midrange Knob	Fender neg feedback
Fender Normal Channel	Fender replacement parts	Fender Reverb Both Channels	Fender Reverb FX loop
Fender Reverb Reissue	Fender Reverb Transformer	Fender RI Reverb mods	Fender RI Reverb Tube
Fender RI Reverb Tweaks	Fender SF vs BF	Fender Silverface facts	Fender speaker recs
Fender Super 60 price	Fender Super pricing	Fender SuperChamps	Fender The Twin
Fender tone circuit boost	Fender Tone Circuit	Fender Tone Circuits	Fender Transformer Codes
Fender Treble Caps	Fender Tube Chart Dates	Fender Vib Rev Pedal	Fender vibrato pot
Fender Vibrato Ticking	Fender Vibro King circuit	Fender Vibrolux RI review	Fender VibroVerb
Fender Was Dumb	fender	Footswitch specs	Grid Blocking
Homebrew Vibroverb	Invert normal channel	Knob Changes	More Pro Reverb
Narrow Deluxe Chassis	No 5R4s	Normal Channel Delay	PA 100
Pot Tapers	Princeton Adjustable Bias	Princeton driver mods	Princeton Mods
Princeton PI Headroom	Princeton PI Heater Cathode v	Princeton PI Mod Layout	Princeton Reverb Power
Princeton Reverb Tweaks	Princeton tone bypass	Princeton Vs Deluxe	Princeton with 5881s
Pro Reverb baffles	Pro Reverb History	Pro Reverb Orig Speakers	Pro Reverb Parts
Pro Reverb Questions	Pro Reverb Speakers	Pro with a 15	Proper Blackfacing
Pull Boost Failures	Red Knob Twin problems	Reduce Champ Screen Voltage	Replacing Glued Baffles
Restoring Grille Cloth	Reverb Amp Effects Loop	Reverb Fixes	Reverb Pan Bottom
Reverb Trans Specs	Reverb Unit Mods Page	RI Bassman Mods	Rivera Designed Fenders
Scrape Vibrato Pot	Screen Resistors	SF Deluxe mods	SF Deluxe Reverb Questions
SF Reverb Cathode Resistor	SF Vibrolux Changes	Shielding Plate Problems	Showman vs Twin
Silverface Changes	Silverface Pro Reverbs	Small Trannys Sometimes Better	Super Champ 6C10
Super Molestation	Super Too Much Bass	Tolex Repairs	Tremolo Tick Tips
Tweed Champ Filter Caps	Tweed Deluxe Bypass Cap	Tweed Deluxe Transformers	Tweed Twins
Twin Reverb History	Twin Reverb overdrive	Twin Reverb Variants	Vibrato Click Fixes
Vibrato Tick Svc Bltn 9	Vibro King fat switch	Vibro King info	Vibroverb tone
What is Hi Pot	What Makes Fender Sound	What Was Ice Cube	Why 68K Input Resistors
Why No More Cloth Wire	Why Silverface Changes