How to repair grounds Fender 5F6A Bassman MojoTone kit Fix build errors Tube guitar amp Magic

Sent to D-lab by a fellow KZbinr Ron C. He built this kit hoping for the best, however struggled with noise, squeals, feedback issues, he decided to send it to me for evaluation. Well, the amp was built per the instructions. It looked very nice. I could tell that Ron spent the time to construct it neatly. The main problem turned out to be bad grounding, mostly in the preamp area. Back in the day, Fender utilized a brass plate that acted as a common ground plane. These new kits do not have that feature, so achieving a good ground on these chrome plated chassis is a challenge. I decided to install a ground bar for the preamp section, also installed a hard soldered ground lug in the power transformer area, separating as per Vintage amp designs. Magic! all of the problems disappeared! If you are struggling with noise out of control kit amp builds, look this over closely and incorporate these easy updates. You will be very happy with the final results.

[@rciancia]

Terry - What a great video and thank you so much for all of your work on this amp. I built this about 3 years ago when I was much less experienced and even though I looked it over, I was not able to find the ground issues - but thanks to you , I have learned a TON !!!! Thanks man... and thanks to Tony !!! That amp sounds great. lastly, I am glad you and Marcia enjoyed the wine.... no workbench is complete without some vino. DLAB Rocks !!!! Thanks guys....

[@d-labelectronics]

Hi Ron, Yes Sir, a great project. Appreciate the wine bonus! You are a good friend. TD

[@umajunkcollector]

Rin, looking forward to a vid of you playing bass on the amp when it gets back to you, perhaps SPILL THE WINE AND DIG THAT GIRL. The "ground" here could have some snow on it soon. BTW, Edie gets that good wine in a box, lol. But my brother Tim treated her to a bottle of her fave, Martini and Rossi Asti Spumanti, is that Italian by chance? Those old Fender Bassman amps do sound great. ENJOY! DON

[@rciancia]

@@umajunkcollector Thank you bro. This one kicked my butt, but thanks to Terry its gonna be a killer now. I am looking forward to taking her for a test run.

[@monto39]

I'm in the middle of a much simpler build (5E3 kit). This video helped confirm the grounding scheme I have set up should be good (fingers crossed). Especially helpful are all the other tidbits on resistor placement, etc. I also appreciate that a positive attitude was kept towards people building kits - so often amp techs take an attitude that we amateurs have no business building them.

[@paulsullivan6392]

You had WAAAAAAY to much fun with the intro on this one buddy. Well done.

[@bobblum5973]

"Proper testing of an amplifier requires the proper signal generator." "Hey, Tony, come over here a minute!"

[@THE1668KID]

Im drinking some great wine from Sicily watching your video

[@MadScientistGuitarLab]

Best beginning of a D-Lab ever! Love the car on a string and the “eye” of the old scope!

[@jwilko7998]

Wow Terry that was some big audio tube you un boxed right at the end and drinking the red liquid out of it!! Love the great content a pleasure to watch.... Thank you!

[@d-labelectronics]

Thank you my friend. I will continue to provide good content. Glad you like

[@daveogarf]

IT'S TONY FOR THE WIN! Terry fixes some minor problems, and Tony blasts the doors off with pure talent!

[@Bigjoedo66]

Another great repair Terry!!

[@kendipietro6855]

I can only imagine the fun you had soldering those preamp ground wires. It's like building a ship in a bottle. Nice work, as always.

[@robinosborne266]

Another great video Terry - keep ‘em coming!!

[@DoItYourselfMusician]

Great job Terry and Tony!

[@jerryking2418]

Great info on grounding. Thanks for sharing.

[@theguitaramptech]

Thank you for another excellent video, Terry. I admire your eagle eye spotting the tiniest of issues.

[@bobr8565]

You make it fun to watch..love the theatrics. Terry..cheers

[@Joshua-to5bl]

Thank you! Extremely helpful

[@shalmanezer4193]

Love the custom cinematic opening.

[@johnsimms3957]

Good job Terry.

[@donhiscock6933]

Hi Terry grate video love the refferance to the twilight zone love how you entertain us while showing us the right way of repairing thees amps thank for all your grate videos.

[@thomascoulter6121]

Delightful! Thank you!

[@TheBoptillyoudrop]

I had a Bassman years ago, I am really speculating in DYI’ing one. Terry Ned’s to make he’s own channel with some of that tough’n nasty good times guitar content? You are some great fellas. Thanks for the great videos!

[@tomasjones3755]

Great & practical video! Also - BEST D-Lab intro, so far. Hope you keep the Twilight Z theme going.

[@eckenstehernante1]

Hey Terry, thanks for the great video. Because of you i have build my own amp and no cablamo. Greetings from Germany

[@marekgitarzysta5193]

Wow. The best "amp repair" channel got even better 😎 I just adore your videos. They teach, they entertain. Why ask for more?

[@edwardhannigan6324]

Love it...Great repair and entertainment..! Mixed in with serious refreshments at the end..Thanks for sharing your expert knowledge..Ed..u.k..😀

[@P40Flyer]

Terry - I'm in the middle restoring a Ampeg Reverb Rocket 2. It has a slightly corroded chassis, and had may other issues (including being retubed wrong), your videos and tips have been indispensable to me as I work through this amp and getting it to work the way it should. Your modifications and tips on grounding are right on!

[@kxmrock]

Awesome Upgrade, Noticed 4ohm Load Resistor Prior to Playing it

[@PLINKER]

Thanks for helping Terry with the wine Marsha! There is no electronics involved with opening a bottle of wine. Help might be needed!

[@DeadKoby]

If you don't have a brass plate, a ground bus wire is a great option.

[@lincolnmicrophonellc]

Your videos are so fun and informing.

[@d-labelectronics]

Thank you Sir, Glad you like

[@fiddlix]

That amp sounds amazing. Thank you for sharing your work of excellence.

[@d-labelectronics]

Thank you Sir, Yes I was pleased with the turn out

[@willykanos1044]

The shop speaker looks home-made. I have built a few speakers in my time. Does your shop speaker have more than a woofer? Can you tell us what kind of speaker is in it?

[@doronlivny]

Terry, Your channel is growing on me... Great job! And as one wine enthusiast to another, I thought a little paring chart between wines and fixing tube amps is in order (measures are plate voltages): 150v-200v = Malbec 200v-300v = Merlot 300v - 400 = Pinot Noir 400v - 550v = Cab/Sauv 550v -over= Zinfandel Enjoy!

[@billedwards2657]

*cringes at existing grounding scheme* great info here especially about the requirements on these new kits. 👍

[@electrolytics]

Yeah.....there we go. Get a little freakiness in there. Thanks D-Lab.

[@victorbodon]

Thank you for making honest videos they have nothing to do with politics or the pandemic. It’s nice to be able to get away for 10 to 20 minutes at a time and know that I can watch your videos without having to worry about any drama. Thank you!

[@d-labelectronics]

Yes Sir, I feel the same

[@robinosborne266]

Hi Terry, sorry to be a bother to you, but the subtitles have disappeared on this latest video. Thanks for all of your content. I have learned a lot from your channel and have set myself the task of building my own amplifier (a very simple one) after I have had my surgery to fit a Cochlear Implant (bit pointless doing it at the minute as I wouldn’t be able to hear it!!!😂). Take care and thanks once again.

[@d-labelectronics]

Hello, Try again, I just made sure it was enabled

[@robinosborne266]

@@d-labelectronics Thank you Terry - it is so much appreciated. Take care and stay safe

[@tubeDude48]

You're 1 CRAZY DUDE! :D Love your video's

[@d-labelectronics]

Thanks man! I am staying true to the D-Lab path. More to come.

[@cheycasters]

Doctor Genius Terry. Dang you know your stuff!!! Killer

[@kxmrock]

He's Awesome

[@ElliotGKnapp]

I knew when I heard “grounded directly to the chassis” that we were gonna be in for some Snozzaramus!

[@d-labelectronics]

That iron has character!

[@johnnaighley9252]

Yep, no time to snooze for snozzeramus...

[@bkbinj6320]

@@d-labelectronics That iron is a character!

[@willykanos1044]

I have another kind of high-wattage iron. It's a 350 Watt Weller soldering gun that makes short work out of chassis soldering jobs. Got it at a yard sale.

[@dambuster6387]

Nice work, sounds great, I just bought a tube tester and tested ones that had been not in use for many years 6K7,s the grid leak was very high put them back into my national HRO from WW2 left it on for a few hours and retested them the grid leakage had vanished ? any Ideas Terry.

[@MikeGervasi]

Currently working on a Fender Champ build. His work did look nice and clean. so no fault there. It's easy to miss some things and sometimes the kit's methods aren't the best way of doing it.

[@michaelwoods9005]

There's "miss some things" and then there's "completely ignore the schematic and layout". This amp is the latter, lol.

[@ahmedlasfer8037]

hi, i love the credits d-lab zone, the guitar amp is really great and as usual i learned a lot of tricks i didn't know, please can you save me a drink of the red chappelet? lol

[@Bob-ir2bj]

Best intro ever! Oh yeah, and the video wasn't bad either.

[@Maxime1602]

hey man cool video i have the same issue on my princeton reverb i think will this also work?

[@jogreeen]

top vid

[@ertreri]

:) super video.

[@sunnyray7819]

Man, this amp looks super simple to build.. Not a ton of resistor and caps.. Class A..

[@matthewf1979]

I am a 5F6A specialist. I always, always, *ALWAYS* use a brass plate and follow the original design that left the factory in late 59/early 60. The Fender schematic is incorrect, the biggest things are the LTPPI, mid slope resistor, bass tone cap and the presence cap/pot/resistor. All of the things I’m talking about can be found here robrobinette.com/5F6A_Modifications.htm I wish Mojotone would send out a brass plate, they aren’t expensive ($3). I wish they would also fix the schematic they send out to their customers. It really is a good kit though, just needs some inexpensive tweaks. Thanks for the video, Terry!

[@brich2929]

@Matt Fields where do you source your plates?

[@michaelwoods9005]

I don't like their cap board layout for the 5F6A and 5F8A either- it has the grid filter and the preamp filter on the same ground wire. When I wired it their way I got horrible noise and motorboating. When I wired it per Rob Robinette's layout (reservoir and grid filters to the power ground, and preamp filter to the preamp ground buss) all was well.

[@bobblum5973]

Regardless of the (good) quality of the repair video, kudos on the toy intro, especially the Space Pod from Lost In Space! 😉

[@d-labelectronics]

Thanks man, I always love injecting some stale humor

[@bobblum5973]

@@d-labelectronics Hey, there's nothing wrong with a little retro(rocket) humor!

[@Retro.Studio]

Yessssss SNOZZARAMUSSSSS 🤟🏼

[@analogblues9606]

Hi Terry! I'm looking to buy a hi watt soldering iron to solder grounds to chassis. Could you please recommend how much wattage iron and maybe recommend one? Thanks

[@davidcrandall7715]

Perfect timing for this video, Terry. I am constructing a 5E7 just now and have encountered a few problems that I think relate to grounding. I was struggling with trying to figure out a scheme to run the ground wire. Currently mine is exposed above the circuit board. I also tried to solder on the backs of tone pots, but that is less than successful, so I have a second buss hanging in the air that connects to the input jacks. I knew this wasn't right, and was trying to come up with a solution to this very problem. Your video is the answer to the problems I am having right now. Thank you so much for putting this out there. How do we get in touch with you if this problem I am having persists?

[@d-labelectronics]

Cool deal man, Hope it helps, if not [e-mail]

[@ahmedlasfer8037]

salut, j'adore le générique d-lab zone, l'ampli guitar est vraiment genial et comme d'habitude j'ai bien appris des astuces que je ne connaissais pas, s'il vous plaît, pouvez vous me garder un verre du chappelet rouge? lol

[@ericmorrison794]

D lab rocks.if a person doesn't know who d lab is or uncle doug they are not cool in my book.

[@Roy-xe9is]

Just getting starting w building. Best kit for the 5F6A?

[@robinr.2233]

Chappellet....impressuve

[@swingarmer]

He chose the yellow code! :)

[@dhpbear2]

Wow, A Lost in Space 'Space Pod' model! (0:26) Rare?

[@gaylen8467]

Nice flying toy collection

[@d-labelectronics]

I also have a flying circus here

[@mikemiller4838]

What can u tell us about your tube tester

[@johnhbox7767]

Happy Christmas 3rd

[@brich2929]

Terry, you used an 18 ga. ground runner. What would be the benefit of that gauge versus using a slightly thinner gauge, say- 20ga.?

[@jamiboothe]

Portughoul! What was that sound bite you used?

[@halbertking2683]

D Lab Zone with Thing , how much better can it get ?

[@SwanseaTitanFan]

Terry, by now you should be able to play a few cowboy cords or at least smoke on the water.

[@Spookieham]

Would love to send you a bottle of Margaret River red from Western Australia but you can't ship wine into the US☹️

[@ix-Xafra]

I have a soldering iron and am in Queensland Horsetrailier. Send wine here ;)

[@dhpbear2]

Link to Ron C's KZbin page - kzbin.info/door/tBhBfhFQwBt5xsryxA_grA

[@Starcrunch72]

Are we seeing a pattern here with the Mojo kits? Slightly incomplete instructions? or Schematics? Anyway, Terry would the "Hakko 557V-V12 200W Matchless Soldering Iron" available on Amazon a decent replacement for the Snozoramus?

[@KK4CNM]

You left the demo audio in from Pond5

[@THE1668KID]

Good evening from Italy.. I have a question. A few days ago I bought an old vintage tube radio/turntable. I just bought it last week. I used it a few times with no problems. And then On friday I plugged it in again to listen to my records. But this time unfortunately sparks went off when I plugged it in. This action produced sparks from the outlet and cut off all the power in the house. Im hoping I did not ruin by Lesa Gutex turntable. Any feedback from you would be appreciated. Have a great day.

[@pneumatic00]

Most likely, an old tube radio or amp might have sat on a shelf for 30 years before you bought it and plugged it in for the first time in those 30 years. The most likely problem is the failure of electrolytic caps that just dry out and go bad over time, especially that much time. It's also possible that the power cord dried out in a way you didn't notice and the insulation on the power cord failed, the conductors touched and shorted. Without seeing it, obviously I am only guessing, but those are the most likely problems. Usually, if you get sparks from either of those issues, it will not destroy anything else. It CAN, but probably not. Got to get it to a repair tech!

[@THE1668KID]

@@pneumatic00 Thank you so much for taking the time to write back and togive me such knowledgeable advice.

[@pneumatic00]

@@THE1668KID You're welcome! I miei migliori auguri per te!

[@steveh1273]

what is that stud you are using to mount the grounding tabs for the transformer (the 1st tab you installed; looks like a rivet)?

[@d-labelectronics]

Hello, Yes a steel pop rivet, ground the metal under then soldered

[@scienceobrien8335]

Nice work, how did you get your training? I’m always amazed at guys who can figure that stuff out.. 73’s KI6NVP

[@d-labelectronics]

Hello, I was USAF for 12 yrs working on Minuteman missile systems

[@jeremiahlyleseditor437]

Great Video. Terry, I did not see where you grounded the positive side of the bias capacitors. You mentioned that there was a jumper missing and after the repair there still was none, what happened.

[@d-labelectronics]

Its connected to the end of the ground buss, Also connects the Presence & Mid pots, Yellow wire with a red end

[@dougtaylor7724]

What is the action figure? I had one with a backpack called Major Matt Mason as I remember that looked like that but was smaller. Oops, you mentioned it later in the video. I got my toy guy in 1970-71.

[@d-labelectronics]

That is Captain Lazer, He was a Major Matt Mason figure offered in aprox 1969

[@fen79strat]

Q: could you use copper shielding tape behind pots to connect for casing ground?

[@hestheMaster]

Weak fix. Get some wire and do what Terry did.

[@fen79strat]

@@hestheMaster thanks for your opinion but the question wasn't directed to you,

[@hestheMaster]

@@fen79strat Terry won't answer you on this one! Your even LUCKY I did! Comments section is opened to everyone and anyone , unless you know a rules change I'm not aware of.

[@fen79strat]

@@hestheMaster I told you thanks. Not really sure why you think I'm lucky; some narcissist insults my question that was posed to someone else. Now please lend me your magic mirror so I can be as great as you! Now have a great day.

[@hestheMaster]

@@fen79strat Well you made your mistake thinking that only Terry would answer a question posted here! That is why I foolishly thought you were of sound upbringing kid. Doesn't take a narcissist to do that in any comments section but you need to see other videos where others do the exact same thing! If you want him to answer YOUR question personally here is Mr.Dayton's email: [e-mail]

[@gigmandrew8975]

Did you sand the chassis where you installed the terminal board for the ground?

[@d-labelectronics]

Yes, used a dremel tool

[@timmooney7528]

Was that amp all stock and un-touched, as in it worked somehow when it left the factory?

[@d-labelectronics]

Nope, this was a kit. Check out MojoTone on the web

[@atech9020]

I am not a fan of using the back of the pots as a grounding point. I think it looks bad, and IF the case ever loses continuity, you have no more ground. So I always run any ground to a grounding bus. This ensures that all necessary grounds go to a single electrical conductor that can then be connected to a common ground following good star grounding methods.

[@BebetaYoPapaniKoka]

first one! :)

[@Roy-xe9is]

I trust anyone who starts the clip w a glass of red

[@taylorfusion]

Fact check I’m not so sure about some of the ghouls coming from Portugal!

[@p_mouse8676]

@ 2:34 , you're not only relying on the integrity of the chassis, but this is also the perfectly recipe for ground loops. and other issues. Btw, according to nowadays standards, a ground/earth has to bolted on with it's own lug on a clean sanded area on the chassis and tightened with serrated washers (ideally with a lock nut) That way you also don't need an heavy soldering iron, solder can get brittle after a while, although a washer could corrode as well I guess.

[@tperki2322]

Here is the link to Ron's channel: kzbin.info/door/tBhBfhFQwBt5xsryxA_grA. Had to transcribe that off the screen LOL. Great work Terry. Hope you enjoyed that Cab, looked really inky. Mmmm.

[@moodyga40]

looks like death cap fitted

[@d-labelectronics]

That Cap is actually on the HV Stby switch

[@michaelwoods9005]

That's the "anti-pop" cap on the standby switch. A 100K 2W resistor across the switch works too, and allows just enough current through to slowly charge the reservoir caps as the rectifier warms up.

[@hestheMaster]

Ghouls buy their cookies from the ghoul scouts. Hungarian ghouls love ghoul-lash. At parties they love drinking ghoul-aid. I was at my ghoul-friends but later played a round of ghoulf with some fiends. OK I'm done. Good fix Terry. Cheers !🍷🍷🍷

[@d-labelectronics]

Thanks for being there for me Sir

[@dalesmith4089]

What/Who was that clip from?

[@hestheMaster]

@@dalesmith4089 My own commentary was a recreation of things said by Ron Sweed as The Ghoul on decades old Detroit TV! I know cheesy at best but if you don't remember kids TV back then that was show hosts for kids did back then. Google Ron Sweed or see some stuff by him on KZbin.

[@hestheMaster]

@@dalesmith4089 At 4:50 you hear Ghoulardi who was a horror movie host on Cleveland TV back in the early 1960's. Well he may have said those things I wrote over the years , it was all live TV back then. Look him up on KZbin. He was really Ernie Anderson and very good friend to Tim Conway and was the Carol Burnett Show announcer. Some thought it was actor Lyle Waggoner's voice but no that was Anderson.

[@dalesmith4089]

@@hestheMaster Yaah, I *thought* so! Turn Blue! I'm from Cleveland, (where the ghoul broadcasted from) and the Ghoul was just part of the culture back then. Rememner, Parma, Spelled Backward, is A M R A P.. (There actually is an Amprap street in Parma).

[@jeremyturner2873]

Mmm... Right on the edge of breakup. That guy will take pedals like a MF!

[@merrittderr9708]

As always I enjoyed the video. Don't know what the quality of the instructions are in those kits, but clearly they aren't good enough. And I enjoy Tony's playing, but I wish you guys would wear masks when you are in that room together. Maybe you hadn't heard about the pandemic?

[@codpug]

dlab is my favorite drunkard

[@roberthurless4615]

I am wondering how long you and Marsha have been married?

[@d-labelectronics]

A bit over 36 yrs

[@roberthurless4615]

@@d-labelectronics it is 37 years for us.

[@ivanduke]

Snozzzzzz!

[@cjay2]

You've truly lost your mind, now. Perhaps you should move on to solid state repairs or elementary basketweaving? (joking).

[@bluesky6361]

Really stupid intro. Just based on that, I didn't bother to watch any further.