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Fender 5B3 tube amp

T

tube-a-lou

Addicted Member
Hi all,
I don't know if any of you guy's have experience with a Fender amp here but
it's tubes so here goes, I got this amp awhile ago and it was worked on and looking
the schematic there are five resistors that are 250K but were replaced with 220K,
I've been searching for nos 250K resistors but so far I found 270K which I have
but I found a source of 240K which is closer to the 250K so should I go for the
240K and take out the 220K to get closer to spec or would the 270K be good?

Thanks
5b3_lay #2.jpg
 
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220k will be fine. Those old Fenders often used parts with a 20% tolerance. Same goes for caps, if there's a .05uf it usually becomes a .047uf when replaced.

It's the beauty of Leo's stuff. Rugged and fault tolerant. I've seen old Fender amps that were working but technically they were blown up. Great stuff.
 
tube-a-lou said:
Hi all,
I don't know if any of you guy's have experience with a Fender amp here but
it's tubes so here goes, I got this amp awhile ago and it was worked on and looking
the schematic there are five resistors that are 250K but were replaced with 220K,
I've been searching for nos 250K resistors but so far I found 270K which I have
but I found a source of 240K which is closer to the 250K so should I go for the
240K and take out the 220K to get closer to spec or would the 270K be good?

Thanks
View attachment 2435589
Click to expand...

:eek2:
You have a working 5B3 TV Front Deluxe? First off, 220K-ohm is fine. The only resistor which maybe critical is the one hanging off the 6V6GT's cathode. It should be within +/-20% tolerance. I like metal oxide or wire-wound resistors in this 6V6 cathode position. I'd replace the bypass cap, too. Go to 25-mfd with 50-VDC rating, as house wiring voltages have increased in the last 70-years. That is a 70-year old amp! I'd replace all electrolytic caps and measure for DC leaks off those ancient Astron tone caps. I'd love to hear an audio file of this gem.

TV Front Deluxe (1950).jpg

TV Front Deluxe back (1950).jpg


Here's a schematic:

Deluxe 5B3 schematic.jpg
.

Here's my 1955 Champ. With what I changed in the circuit:
coupling cap voltage after (SMALL).jpg

Mine has Lupe Lopez's masking tape signature. Does yours?
lupe lopez.jpg
People have offered me over $4K for mine. I bet your Deluxe maybe worth nearly double. You may want to get that puppy insured.:idea: :D
 
Last edited:
Falstaff said:
Yeah, that's about twice the going rate but then again if it is a tone monster as many were/are...I would hesitate to sell.
Click to expand...

Remember, I replaced the 'lytic caps and checked for leaky coupling caps. Checked the resistor tolerances and put in an Weber Alnico speaker. I still have all the OEM parts. Many tweed Champs need servicing before they are reliable, again. :)
 
JohnT123 said:
Lupe, Lupita, Maria and Gloria have all turned up in my restorations. I always go to the masking tape as my first stop in any vintage Tweed amp.:)
Click to expand...

Every Fender tweed I've worked on has great soldering. Well laid-out wiring. The high standard started to slip in the late CBS era. Many mid-1970 through 80s era silverface circuits had rubber insulation on the wiring (I love cloth covered --- even though claimed not as safe), with messy layouts. Sad...

Pro_amp_1962_front2.jpg
My 1962 Pro layout.

VLR 1972 left side chassis.jpg
My 1972 Vibrolux Reverb layout.
 
Somehow I wound up with a few new stock Fender blue wax caps.
Anyway, I don't think I've ever seen these in any pictures of Fender amps.
I loooked them up and found they come in blue, yellow and red. Should I use them or just toss them?
 
Lavane said:
Somehow I wound up with a few new stock Fender blue wax caps.
Anyway, I don't think I've ever seen these in any pictures of Fender amps.
I loooked them up and found they come in blue, yellow and red. Should I use them or just toss them?
Click to expand...

Are they like the "blue bombers" in my Vibrolux Reverb photo (lower one)? They are not good caps. Those and the late 1970-80s flat-brown (with yellow lettering) caps. Cheap, yes. Tone, no. You are better off using SBE Orange Drops.

Bronco_1968_guts cap can.jpg

Dull brown coupling caps on right side of photo.
 
Mr Boochie said:
Are they like the "blue bombers" in my Vibrolux Reverb photo (lower one)? They are not good caps. Those and the late 1970-80s flat-brown (with yellow lettering) caps. Cheap, yes. Tone, no. You are better off using SBE Orange Drops.

View attachment 2436691

Dull brown coupling caps on right side of photo.
Click to expand...
No, they are cylindrical axial caps. They are wax and tin. I used one in a pinch until I ordered something else.
20211229_164834.jpg
 
I don't remember. Or why I even ordered them in the first place. Maybe I clicked on the wrong part at some point?
 
Lavane said:
I guess they are to replace the original vintage caps in some Fender amps? :dunno:
https://www.tubesandmore.com/products/capacitor-fender-150v-wax-paper
Some are mylar, some wax and paper, wax and tin, etc.
Click to expand...

Thanks, for the AES link. If you are looking to maintain some of the period vintage looks and tone... I like Jupiter caps.

https://www.partsconnexion.com/capacitors-film-jupiter-vintage-tone.html

https://www.partsconnexion.com/capacitors-film-jupiter-red-astron.html
 
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