How to fix Noise Fender Bassman 50 tube guitar 6L6 amp D-lab electronics repair shop

Lots of these Bassman amps rolling thru D-lab these days. This one is identified as a 50, seems to be the same as the others I have worked. It suffered from the typical noise generating issues. I had to repair that before installing the Master volume control. These amps are very nice, since they are not plagued by added features that also cause noise/hiss. If you like to use pedals and dont need spring reverb or tremolo this is the amp for you. Not too heavy and with the master volume mod, it can be throttled down for practice/recording level. D-lab has been swamped lately, however keeping the vintage amps as top priority as I know they are the kingpin for professional players. Thanks for sticking with me guys, I will keep the videos rolling. TD

[@michaelkesti3917]

Love the opening cavalcade of Bassmans.

[@budandbean1]

Thanks Terry, really like watching you work on the Bassman Amps because they aren’t too crowded to see what’s going on and when you explain something, it easy to see what you’re talking about. Thanks for the education. 😊

[@DavidBrown-ez5jc]

Terry you are a amp tech legend you explain and show great videos thanks for all these years of your master classes

[@mattdixon333]

too cool! I love these guitar amp videos. Thanks!

[@bobvines00]

Terry, Thank you for another informative video. I like seeing how you use a simple 'scope and an audio signal generator to find & show the noise created by failed/failing components. And what the replacements look like on the 'scope. Thanks again.

[@1truemoose]

It's a pleasure to see a real pro at work.

[@tomcurrie7249]

Orange drops in old Fender amps make me sad. Those blue caps are highly reliable. I agree changing the grid coupling caps to the power tubes. Shotgunning the blue caps for orange drops is unnecessary.

[@kosmicwizard]

Those aren't the same blue caps as in my 67 BF Bassman, these look just like the brown turds that are typically in SF heads, only they are blue for some reason? All of my blue Mallory's are original except for the 2 that feed the power tubes, I put 0.22 Jupiter caps in there, I don't want to risk blowing my NOS RCA powertubes. And if I don't teach my son amp repair before I pass and he brings it in for repairs and the tech pulls out all the caps arbitrarily, I will roll over in my grave!

[@TheRadioShop]

Great tutorial as always Terry.

[@RandallDibble]

Great Video - most importantly it applies to most all tube amp diagnostics and repair. It inspires me to dig into my old Traynor YBA-1 !

[@gabrielespinoza1303]

Español Español

[@richardweinberger6302]

Great information here. Thanks, Terry.

[@jackneff179]

Hi Terry nice video. I've been a ham since age 12 but having lived in CHina for13 years I couldn't continue here obviously. What really bothers me is that young folks aare not interested in the hobby any longer..what a pity. Their phone has taken over their somewhat limited minds. As a kid my biggest want was a DX100 but that never hapened. I joined the navy and rode submarines arund for 11 years as a radioman. I sure do miss the hobby. My last call sign wasVQ9TB WHILE AT DIEGO GARCIA AS A CONTRACTOR. hAD A LOT OF FUN WITH WITH THAT CALL. 73'S AND KEEP THE VIDEOS COMING

[@daveogarf]

I MISS MY BASSMANNNN! ‘68 silver face, used to play (Farfisa) organ bass through for our little garbage... uhh, garage band in the late ‘60s. It was a real workhorse, and did an amazing job(ber) with guitar, too. Thanks for the look back, Terry! (PS - grew up in Cheyenne, home of FE Warren AFB).

[@nine-graves]

What an intro!!! GJ and Keep up the good work Terry!

[@nor4277]

Learn some stuff here about caps,another great video ,I sure the owners going to be very happy .fender great stuff.meet video

[@electrolytics]

Thanks D-Lab.

[@sam127001]

very informative and interesting video !

[@rafaelcoli4797]

Hi Terry! Great video. Just bought an ab165 1967 silverface bassman with low volume and almost no break up. Any advice in what to look for?

[@Steve-wz5pz]

That little green cap was identical, down to the orange spot on top, to the one in my Bassman 50. Tremendous replacement coincidence, or they were stock. I'm thinking stock.

[@jorgemellooliveira9611]

ótimo vídeo congratulações

[@IronandWire]

I hope we can all agree it's about the circuit and not the original wiring/caps. Modern orange drops should sound as good if not better than the original components.

[@Paulmccarthy6801]

I finally got a chance to get in my bassman I was doing your tap test for noise oh boy lots of noise. There’s 2 or 3 things in there I tap on and it gets very noisy. When I get the money I have to send it out to you. I got the noise to stop for now by tapping on those things but I’m sure it will come back.

[@kendellbise8875]

Were can i learn how to hook up an oscilloscope to the amp board so i can see faults in the components the way you do? Im not trying to become a tech like you i just want to be able to find and replace faulty caps etc. the way you do, i have a delta blues that squeals like a stuck pig on the OD channel and growles on the clean channel, one power tube and two pre amp tubes are microphonic, iv orded new tubes but if there are faults on the board putting them in will just wast em. any suggestions? Im 65 so i do everything slow and patiently.

[@RobertKohut]

Nice!!

[@bobyk87]

Those coiled wire cable shielding I never seen before.

[@jonathanbobohunt6507]

I believe the 3 prong plug is original on this. I am working on one now and it has a 3 prong. the aa371 schematic shows a 3 prong cord also.

[@flintdavis2]

Thanks

[@nickbracamonte]

Ahhh man I want your soldering iron.

[@joaofernandes6323]

Awesome

[@markvincent522]

Terry rules!

[@AntonioCavicchioni]

Master class! Thank you very much for this video. You teach! No wine this time?

[@d-labelectronics]

Hello, Yes, had some wine after the repair, just did not show it due to time constraints. Glad you like ; )

[@dhpbear2]

For testing noise floor, wouldn't it be easier to connect the speaker so you can hear the noise audibly when you tap the components?

[@d-labelectronics]

Scope is my go to instrument, you could use a speaker

[@mikeviking6144]

Sometimes the speaker will act like a microphone and pick the taps and thumps, then relay them to the scope. Using the dummy load eliminates this

[@flintdavis2]

⁠@@d-labelectronics brand new$1,100 fender bassman tube amp on clearance at GC I offered $100 they wanted $300 , plugged it in at store in made a loud noise one tube was flashing, then the amp went dead. I want to try and fix it. After watching your videos I think I can. Or can I ship you the guts for repair?

[@kenhancock8931]

First ;-) thx for the vid terry

[@RobertKohut]

You the Man (Bassman)....LOL

[@Only1Shadow]

Ceramic Disc caps are intended for RF circuits and non-critical applications - they very rarely go bad, and don't tend to drift, but the ceramic is usually somewhat piezoelectric making them microphonic in right from the factory... They gotta go. Carbon resistors drift and can tend to be noisy as well, so unless somebody wants it to look original I only put metal film resistors back in. High Quality components make a difference!!!

[@TheRoiderien]

+ the use of metal film caps--they're stable and QUIET

[@MrAletube]

those are very old technology,today we can have certain type of ceramic that are also very good for audio,but mostly at low voltage.

[@kosmicwizard]

I am in the carbon camp, they add mojo

[@DennisMurphey]

I have a 1990 Fender JAM 25 watt SS with 12 inch 8 ohm speaker. Do you have or help me make the SS portion a preAmp then put a 25 watt Tube Amp for he speaker in the combo box or as a set-top head. I need to tap speaker signal out of the unit before the SS Amp. Need to learn where that is. Where do you get detailed schematics? What parts should be replaced in the SS circuitry? Can i replace push button with pots for more tuning control. Truly enjoy your crazy stuff. Need help arround the edges. Dennis

[@DennisMurphey]

Where can I get Schematics of fender stuff?

[@DennisMurphey]

Got the schematics from Fender now I need someone that knows what he is doing?

[@RaulHernandez-lg5nw]

Bend the retainer arms up and they will work!!

[@daveogarf]

Tweakity doo-dahhh (5:34), tweakity-dee ayy. Wonder who is microphonic... today...

[@christopherreed2694]

Will you be my dad ? You rule man

[@williamscaliarini8201]

I have heard ceramic caps are responsible for the old fen sound

[@MrAletube]

people can believe to anything,and most of the tube amp gurus wisdom statements are all made up to sell something. try for yourself with a bunch of different flavor caps,and make blind tests with your friends,then draw the conclusions.

[@LuchoJ2110]

As long as the caps are the same specs (value,etc). The amp circuit and everything should be the same,nothing in the equation has changed , just replacing an old one for a newer one. Therefore no noticeable change in the sound.

[@josephfelice601]

VERY interesting. Outside of noise, would these microphonic components be complementary to the tone? From my experiences, the most scientifically correct circuit does not yield the best tone. Thanks for posting!!!!

[@paulkielt9301]

Those kind of retainers are a total bullshit! I never saw power tubes escape at night when you're sleeping. If your tubes move it's a good sign you have some cheap sockets.

[@peterstacey3720]

Why do americans. Say sorder. When it is soldar ?.????

[@edwardebel1847]

Why do Brits say shed-ule when its sked-ule? What shule (school) did you all attend? Or did you grow up on a shooner (Schooner?) And BTW, we DO say "solder"...you folks just have hearing issues...just sayin'...you want to pick on Terry? Bring it! (Just kidding...maybe you're not even a Brit...Aussie? Or South Effrican? Kiwi?...)