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Post subject: Re: 1971 Super Reverb
Posted: Wed Jun 28, 2017 6:34 pm
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What kind of gomer does that?

Drop and give me twenty, maggot!
it was hot,jjk and it took about 20 to clean the glass from the kitchen floor!

Quote:
The electrolytic caps looked like they were all replaced. Including the bypass. Seems to still have BALANCE POT. You may want to think about changing this to a BIAS POT.

Nice grab. How's the tone?
Haven't fired it up(a few of the tubes look iffy but will go through it after the cap job), figure the caps are all from 2000(replacements on the way, but think I missed one in my order earlier today after seeing the board{I missed the 5ufx25vdc cathode-vibrato cap will have to call them to see if they can add it to my order} ) Yes on the balance pot to Bias pot

PS: There are more pics if you want to follow the pic links to PB


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Post subject: Re: 1971 Super Reverb
Posted: Wed Jun 28, 2017 10:11 pm
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It looks like all the fundamentals are there to back-mod the chassis to AB763 specs. Once the caps are fit to fire up, start thinking about some minor rewiring. The matched quartet of CTS alnico's are the preferred speaker for a Super Reverb so you've got that base covered. Should be an easy project......

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: 1971 Super Reverb
Posted: Wed Jun 28, 2017 11:30 pm
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I have a few days before any lytics arrive so I will re-read The Tube Amp Book section on SF to BF mods.
The matching speakers were the straw for me making the bid initially.

I have a good stash of tubes to roll in it as well, been fortunate to get some sweetheart deals on Ebay over the last month plus and it came w/ nice looking tubes except for the broken one and its unmarked sibling and the 7025 w/ a glass bubble on the bottom(keeps the pins from seating all the way). Electrons will tell more of a story.


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Post subject: Re: 1971 Super Reverb
Posted: Thu Jun 29, 2017 3:19 am
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The CTS alnico ten is a great speaker. I put one in my '65 Princeton Reverb.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: 1971 Super Reverb
Posted: Fri Jun 30, 2017 7:48 pm
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Checking all the resistors, total count was 59 and making my cheat sheet today.
Found a couple 100k resistors on the legs of the 6.3v from the PT to the lamp(barely visible in one of the pics).. and a couple my meter wouldn't read in the PSU- bypassing the 80uf cans which read 90ish uf on my meter.

Mom update: at home and doing well :D


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Post subject: Re: 1971 Super Reverb
Posted: Fri Jun 30, 2017 9:51 pm
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sfceric64 wrote:
Mom update: at home and doing well :D

Found a couple 100k resistors on the legs of the 6.3v from the PT to the lamp(barely visible in one of the pics).


Good to hear about your Mom.

Those should be 100-ohm resistors (brown-black-brown), not 100K (brown-black-yellow).

:mrgreen:


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Post subject: Re: 1971 Super Reverb
Posted: Sat Jul 01, 2017 12:59 am
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BMW2002Ti wrote:
sfceric64 wrote:
Mom update: at home and doing well :D

Found a couple 100k resistors on the legs of the 6.3v from the PT to the lamp(barely visible in one of the pics).


Good to hear about your Mom.

Those should be 100-ohm resistors (brown-black-brown), not 100K (brown-black-yellow).

:mrgreen:
Yup, my bad they are 100-ohm(didn't think they were supposed to be there, from other thread chats) posted that before dinner and brain was partially fried.

I did just complete checking my work vs the spec's and have to replace 16 out of spec resistors.

In the doghouse, should those all be metal oxide or wire-wound 5 watt or is 3 watt enough, both dropping resistors measured over 2x the spec?
The 2x220K cap by-pass, I couldn't measure; will have to wait until I pull the caps. Should these also be MO/WW? I have some 2 watt CC laying around if they are enough.
Still have to figure out the required resistors for the balance pot to bias pot mod.

Thanks for keeping me in-line. :)


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Post subject: Re: 1971 Super Reverb
Posted: Sat Jul 01, 2017 1:12 am
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I like to use metal oxide (2 or 3-watt) or wire-wound 5-watt type resistors, under the the doghouse.

As for "blackfacing" mod... here's a link to ponder...

http://www.guitarplayer.com/miscellaneo ... -mod/15690


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Post subject: Re: 1971 Super Reverb
Posted: Sat Jul 01, 2017 1:23 am
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For the power rail, metal oxides all the way.

Arjay

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Post subject: Re: 1971 Super Reverb
Posted: Sat Jul 01, 2017 1:51 am
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BMW2002Ti wrote:
I like to use metal oxide (2 or 3-watt) or wire-wound 5-watt type resistors, under the the doghouse.

As for "blackfacing" mod... here's a link to ponder...

http://www.guitarplayer.com/miscellaneo ... -mod/15690

Thanks that was easy!! :mrgreen:
I didn't realize that I had to change the 5u4gb to a gz34/5ar4, we'll see about that part.


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Post subject: Re: 1971 Super Reverb
Posted: Sat Jul 01, 2017 2:27 am
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sfceric64 wrote:
I didn't realize that I had to change the 5u4gb to a gz34/5ar4, we'll see about that part.


All of Fender's GZ34-equipped amps began converting to the 5U4GT when Leo's original circuits were altered to the "new/improved" CBS revisions in 1968 (some models later than others).

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: 1971 Super Reverb
Posted: Sat Jul 01, 2017 2:35 am
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GZ34 will give you a stouter tone, than the 5U4GB. Higher B+, too. You definitely need to re-bias the 6L6GC idle bias, when you change-out the rectifiers.


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Post subject: Re: 1971 Super Reverb
Posted: Sat Jul 01, 2017 7:55 pm
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Got all the resistors ordered today and all in one EBay online store w/ only a few in-lieu of items.
NewOldSounds, I've shopped them several times and have a high confidence in them.
They didn't have any 1w CC's so I went w/ CF for all the pin 1/6 slots(6) plus the 1 needed for the bias mod.
The other was a 470-ohm for the Bronco cathode bypass cap.
Had to mix 3w & 5w MO to get the values I needed for both PSU's.


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Post subject: Re: 1971 Super Reverb
Posted: Mon Jul 03, 2017 11:20 am
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Ordered the remaining parts that I know I needed/wanted. New foot-switch, cover and chassis straps.
Cleaned the tilt back legs & corners, nice to have the originals w/ pat-pend markings.
The straps and handle ends just don't clean up very nice since they are coated.
Measured the reverb tank w/ the DMM, all ok (1-ohm & 171-ohm) and serviced the RCA cable ends.
On installing the tank w/ cardboard cover, most places I read to install the opening facing down.
Is that accurate for Fender style tanks w/ the rubber strips?


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Post subject: Re: 1971 Super Reverb
Posted: Mon Jul 03, 2017 11:43 am
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sfceric64 wrote:
On installing the tank w/ cardboard cover, most places I read to install the opening facing down.
Is that accurate for Fender style tanks w/ the rubber strips?


Correct -- open side down.

Is one of your tilt-back legs stamped with a serial number?

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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