1979 Fender Super Six Reverb Restoration

[Wittgenstein]

I bought this non-working 1979 Fender Super Six Reverb a few years back off Craigslist for $250 and I'm finally getting around to getting her running again. All six original speakers (Quam branded) were toast and falling apart. I was lucky enough to have a buddy donate six original 10-inch Jensens speakers that came out of his Super Six Reverb!

When I cracked it open I noticed that the artificial center tap had burned up and the 470-ohm screen resistors were cracked and drifted. I'm thinking/ hoping that it was just a power tube shorting internally that burned the parts up. I can see that someone had already changed the filter caps, but I will have to go back and double check their work.


What I have done:
Added two 100-Ohm resistors to make a new artificial center tap from heater to ground.
Installed new 470-ohm wire wound resistors on all the power tubes.
Reran the wiring from the 3-prong power plug to eliminate the auxiliary plug and polarity switch.

Next Steps / Questions:
I was planning on giving it a once-over one more time, and then trying to fire it up for the first time to see what it does. I'm hoping that it was just a bad power tube that caused all the troubles. I figure that will help me diagnose whatever else is wrong with this amp and let me know if the transformers are still good.

Is there anything else that I should check before trying to power it on or something I am missing?

The board is severely warped and probably has tweed disease, so I imagine at some point I will have to make up a new board from Garolite to replace it, but I wanted to see how it sounded now before all that work. From my experience with these old Fender amps, I am also suspect of many of the blue and brown "turd" capacitors. I worked on a different Super Six a few years ago back and got it running again, so I am just trying to familiarize myself with the process again.

Flickr Images Linked Below:

• Super Six Craigslist Listing
• Super Six Front
• Super Six Gut-shot
• Super Six Original Condition
• Super Six Burned Resistors
• Super Six Caps Replaced Before
• Super Six Replacement Speakers Front
• Super Six Replacement Speakers Rear
• Super Six New Artificial Center Taps
• Super Six New Screen Resistors
  
  
  

[Justin Thomas]

I was going to say make sure the bias supply caps were changed too, but they were. The 470Ω resistors are the screen resistors, not cathode resistors. Otherwise I wouldn't hesitate to fire it up as it is. I'd probably add some 1Ω@1% resistors on each power tube cathode, just for the sake of easy measuring & math...

That's a sweet amp for sure.

Justin

[Wittgenstein]

I was going to say make sure the bias supply caps were changed too, but they were. The 470Ω resistors are the screen resistors, not cathode resistors. Otherwise I wouldn't hesitate to fire it up as it is. I'd probably add some 1Ω@1% resistors on each power tube cathode, just for the sake of easy measuring & math...

That's a sweet amp for sure.

Justin

Yes, screen resistors is what I meant, thanks! That is a good call on the 1-ohm resistors for easier testing. I ended up doing that on the last Super Six I worked on and it made life a lot easier.

[Randall]

I'd fire it up on a light bulb limiter with no power tubes first.

[Leo_Gnardo]

From my experience with these old Fender amps, I am also suspect of many of the blue and brown "turd" capacitors.

Although our friend at D-Lab on YouseTube has a phobia about these, I can say in my experience it's rare that the "turd caps" are really leaky or totally dysfunctional. I'd say, just march through the usual suspects, and you'll have a fine working amp. Good on you for scoring Jensen replacements for those Quams. Once you have everything else ironed out, if you still want to, swap in some Mallory 150 or Panasonic MPP film or orange drops (orange turds in my book.) FWIW I've had lots of old Fenders & other amps sound perfectly good even with the ahem... unsightly caps installed.

[Wittgenstein]

I had some time this weekend to mess around a bit more with this amp. I dug the old light bulb limiter out of storage and fired it up without any tubes and had no issues. I then installed all the preamp tubes and gave it another test without trouble. Finally after wiring up a old 2 x 12 cab for 4 ohms, I added some known working 6L6 power tubes and gave it a final test with the light bulb limiter and still everything was fine, but it was too late to play loud and really test it out.

Last night I had a chance to open her up and man that is one loud amp. I made a RCA shorting jack to test the tremolo circuit and it sounded great. It gets much slower and nice sounding than some of my other Fender amps. The reverb was on without shorting the RCA jack (not sure if that is normal), but I was able to turn it off by plugging in the RCA shorting jack. There is decent hum when the amp is turned up and touching the chassis with my finger makes it quiet down a bit, so I know it needs a bit of love. All the pots need a cleaning, but I was able to work out much of the scratchiness just by swiping the pots back and forth.

I still need to order and install the 1Ohm resistors off the power tubes for testing, check all the voltages, check for leaky capacitors, etc... but overall I'm super happy with the progress and the fact that every channel was loud and working, and the tremolo and reverb circuits seem healthy and sound good.

[Randall]

I used to do sound in a big club years ago. Albert Collins came in one night with his big ole band, and he was using this amp. Man that sucka was LOUD. I don't think I ever needed to put him in the mix.

[Leo_Gnardo]

I used to do sound in a big club years ago. Albert Collins came in one night with his big ole band, and he was using this amp. Man that sucka was LOUD. I don't think I ever needed to put him in the mix.

Legends of the Iceman! Same happened here at the local rock club. Albert's sound chased most of 600 capacity crowd out into the street, where they could hear him perfectly well.

[66 Kicks]

Any chance that's really a 1973?

[Wittgenstein]

Any chance that's really a 1973?

It very possibly could be. I can pull the serial numbers off the transformers and chassis tonight and try to date it. I just assumed it was a late run due to the Quam speakers and push/pull master volume pot.

[Helmholtz]

due to the Quam speakers

How Quam speakers? The speakers in your picture look exactly like CTS alnicos:



Did you check the manufacturer code (CTS: 137, Quam: 270)?

[Wittgenstein]

How Quam speakers? The speakers in your picture look exactly like CTS alnicos:

When I got the amp it had six Quam speakers (pictured below) that were all falling apart. I replaced them with six vintage CTS alnicos that came out of another Super Six.

[Helmholtz]

I see, thanks. Seems the Quams were no guitars speakers anyway (no paper edge).

[Leo_Gnardo]

Quam story

Quam afaik mostly made speakers intended for distributed PA, like the ones found in office & supermarket ceilings. However late 80's early 90's a Quam 10 inch model was offered by the high quality amp manufacturer THD, an option for their version of the Fender 5F6A Bassman, also as a general replacement speaker. FWIW I wasn't much impressed with those speakers, however the amp is an entirely different story - incredibly well built. But it shows Quam was striving for a place in the MI market. Also, in the 1960-90's folks looking for any replacement speaker might find some more or less useful Quam at a local electronics distributor or PA installer for cheap.

[Wittgenstein]

Any chance that's really a 1973?

You are absolutely correct, thanks. The power transformer, choke, and reverb driver are all from the middle to end of 1973 and the output transformer was made in late 72. The chassis code A67260 falls right in the 1973 range (A50500 to A68000 - 1973). Everything looked original, but it's nice to date it and know they were all from the factory. How can I edit the title of the thread to change the year?