Sudden Volume Jump - 1965 Blackface Fender Deluxe Reverb

[concordia]

My beloved 1965 blackface Fender Deluxe Reverb has been misbehaving -- The volume will sometimes suddenly get very loud and distorted. Seems to happen randomly - not necessarily after getting hot.

I have to turn the guitar volume down to 3 or 4 to cause any decrease. And below that there is no volume at all.

Could it just be a faulty volume pot? They are well-lubed with DeoxIt but I confess that the volume pot has been sitting on 2 for many years!

Any suggestions appreciated!!

[pdf64]

Does the volume on the other channel work properly?

[concordia]

Many thanks, pdf64, for your suggestion. Seems obvious now ... but that's hindsight!

Will try over the next few weeks and report back. Thanks once again.

[concordia]

Sudden Volume Jump - 1965 Blackface Fender Deluxe Reverb

pdf64, sorry for taking so long to respond. (It's taken a long time to be able to reproduce the problem AND to check the other channel.)

The answer to your question is yes, the other channel has the same problem: The volume suddenly gets extremely high on both channels.

Any further suggestions appreciated.

[pdf64]

One possible cause is the power amp global negative feedback loop opening up - dry joint, broken wire, bad resistor etc.
Try tacking a switch in series with the wire from the speaker jack socket to the 820ohm; does operating that give the same effect? Pete.

[concordia]

Thanks, Pete.

If I understand you correctly, I would lift the hot wire to the speaker jack and insert a temporary switch between the wire ad the jack; and then observe if flipping the switch causes a jump in volume?

[pdf64]

Nearly - it's not the hot wire from the output transfomer (that would switch the speaker off!) but rather the wire that goes from the speaker jack socket to the 820 ohm feedback resistor. I'll try to link to an annoted layout diagram. Pete.

[theshredmasta]

fender deluxe blackface, Distortion, Cracks, Volume Altercations..

My beloved 1965 blackface Fender Deluxe Reverb has been misbehaving -- The volume will sometimes suddenly get very loud and distorted. Seems to happen randomly - not necessarily after getting hot.

I have to turn the guitar volume down to 3 or 4 to cause any decrease. And below that there is no volume at all.

Could it just be a faulty volume pot? They are well-lubed with DeoxIt but I confess that the volume pot has been sitting on 2 for many years!

Any suggestions appreciated!!

Fender Deluxe 1965
This is what I have found to be the case with two of my vintage amps, One basic clean the pots with electronic cleaner, I do not recommend changing the Pot unless you know that is the problem, In most casses this would not be the solution from my experience, But this will only stop the cracking while changing your volume level up or down.. What I believe the real problem would be is the big power electrolytic's, as well as the bypass filter, which are also electrolytic's, but much smaller.
The big rectangular box with four screws is where the caps are located, I use sprague Electrolytic's, Some others caps I have heard about, you may loose the bottom end. Do not touch the positive side of caps until discharged, or you could die, its simple process but do your research and make sure they are not holding any volts before attempting to remove and install the new power caps, positive to positive a must..
Next you will find inside the chassis either brown paper / white plastic covered depending bypass filters, 65 brown paper / silverface white plastic or whatever.. 25mfd 25vdc some have double caps in them, they do not make the double ones that I know of, you will have to buy two caps instead, I also strongly recommend sprague caps, some value will be different on other caps, try to keep the same value's, change out all these filters and your problem should go away, but no promise from me.
I have done this to both my vintage amps and both are working great.
I am not responsible if you attempt this and shock yourself and die, I am not responsible if your amp is still screwed up after you do all the work, Just found that in two amps it worked for me, one amp I thought i blew the speakers, As I said I have done this to two of my amps, and never had any problems.
All the caps coast me around $45 dollars but the parts / vashey/sprague caps are climbing the latter fast, I don't think you will find them around next year..
Best Regards
Shredmasta