I’ve never had a problem with a well set up silverface circuit. I restored a 77 Super that blew the doors off my 66 recently and mine was sweet as hell.
Lubbock, Texas ... home of Buddy Holly and The Chirping Crickets ... and THE CACTUS CUTIES! Buddy mighta been using a Bassman or a Twin back in those days.
I just picked up a 71 Super Reverb Silver face, my first one. After watching your video I opened her up and was amazed at how clean the caps and chassis are, absolutely pristine, like new !!! Speakers are also pristine. I'm going to clean the pots and jacks and put her back together. Whole unit is in excellent condition. All tubes are RCA possibly originals ???
Great video. Very informative. I am doing the same kind of work to my 1974 Pro Reverb. The innards look identical. Glad you identified the 5uf 50 volt capacitor. I wasn't sure, because mine is also the same but I thought the number 2 had worn away!
The caps on the 6l6 grids are anti-oscillation and not negative feedbacks. Some call them "tone suckers" but I doubt removing them is audible if oscillation stays away.
They used to be made here in Lubbock TX. Texas Instruments is an interesting company. Not only do they make calculators, but I've heard that they hold the patent on the technology in javelin missiles. 🤯
Not in frame, but I have an identical calculator that belong to my grandfather. He was a math teacher in Lorenzo Texas. He was the first teacher there to get a handheld battery operated calculator. Circa 1971
I have a 69 SR that came with AB763 sticker but AB568 circuit, so I suppose they assembled whatever was available. Mine was blackfaced a while ago and sounds amazing. I am just surprised by the 74% power tube plate dissipation. Fender Amps are typically biased a bit on the cold side, I run mine at 60%, so 74% is quite high, sound meaty and be wearing out tubes quickly. The lead dressing on mine is (surprisingly) much cleaner, again huge variation right from the factory!?
this is a LONG SHOT but for that electrolytic cap that you replaced the 5uf 50vdc are there any others you can use?? it seems to be nearly impossible to find one to replace it with.
So that bypass cap corresponds to the triode that drives the optocoupler bulb. It's yet another subtle change in the circuit that actually happened with a later revision of the silver face. Because it doesn't correspond to anything within the signal path; I imagine whatever difference it makes is likely very subtle. My bet is that it limits the peak brightness of the neon bulb and perhaps optimizes the tremolo circuit as a whole, but it would be very interesting to swap it out with a 25uf and hear the difference. The 5uf appears on the AA1069 schematic and forward.
@@drew945101 Sorry, I was wrongly assuming it was the AB763. Mine is a 69 SR with the AB763 which I am in the midst of doing some maintenance on and the 25uf there was fresh in my mind.
@@jimlabos easy mistake to make, the differences are often subtle. Happens to me more often than I care to admit. Lol The differences can be so subtle that I often complete a servicing an amp with the "wrong" schematic and never even notice.
@@drew945101 The 5uF allows the tremolo speed control to track the adjustment of the pot more accurately. With old blackface amps that used 25uF in that position you would experience a delay in the term speed as you adjusted the pot. The 5uF fixes that and has no impact on tone whatsoever. Well done on the video by the way.
You should do yourself a big favor and ditch the wal-mart special soldering iron and get yourself at least a Hakko of some sort. A genuine one, not a Chinese knockoff.
