How to repair Fender Deluxe Reverb Tube Guitar amp dead channel and random pop when power applied

This amp came to the shop with the complaint of vibro channel being very low in volume. That turned out to be an easy fix. Well of course other issues pop their ugly head. The eyelet board caps were dated, requiring replacement. Then there was a strange intermittent pop when power was applied. That turned out to be a very interesting problem. Great repair with big lessons learned. Watch and enjoy!

[@electroKrunch]

I always love watching what you do and your common sense fixes! Thanks for another cool vid, Terry!!

[@Retro.Studio]

Great work again Terry, as a guitarist always love to see variations mix of vintage ham radios and guitar amps.

[@danhorton6182]

I really appreciate you showing the actual work being done, I don’t even care that your hands get in the way!

[@rs8638]

Just found your channel. Definitely subscribed, you do thorough work which is rare this day and age. Kudos.

[@elwrongo]

Fabulous, just what the doctor ordered to soothe my cabin fever. Loved seeing the blow by blow soldering. Very good for morale to see the pros get hitched on tricky bits too. Great work D-Lab!

[@Mark-ry3ij]

this is what I've been waiting for! thanks terry!

[@robinr.2233]

Ha! Great to see you fight with the eyelet board like the rest of us, I thought maybe it was just me. Great video, as usual.

[@Bigjoedo66]

Another Great repair Video Terry!!

[@luthravin4774]

Extremely valuable schooling!! Thanks a bunch for this one DLab!!

[@waynekozak1462]

Oh No ! Not the old popping cap cage!!!!! LOL Terry you are the best. great video/repair as always. I love Tube Amp theatre.

[@renegade44040]

A1 repair. Very good to see that Fender put back into service proper. NEXT!!

[@harryklippton]

I hope your "NEXT! " is a Skip Simmons reference

[@faultlessguitarsandamps1116]

Well done Terry . Same here . I always cast my eye around for other issues and check it over thoroughly . I would hate for an amp to come back . Best regards and stay in the workshop for a few weeks until CV is all over . I'm slowly drinking my way through some nice Malbec red wines . Cheers Tony .

[@donaldfilbert4832]

That was some great sleuthing on the tube socket !! Also - some very informative CAP info. Thanks a ton for a very informative video !! ;) ;)

[@glenndavis6793]

Very tedious work awesome job as usual Plus you are the man

[@mikesmith8564]

Great video... The overhead shots work well...

[@RichardMcLamore]

thanks! i've been questioning whether i should replace the last 2 resistors in the neg bias line of my super champ--this (& another thread over on tdpri) is pushing me towards 'yes'

[@johnsimms3957]

Good job Terry!

[@stevehead365]

Not an arcing rectifier. My guess was wrong. Very unusual fault, well done for finding the cause.

[@kengevers8738]

Terry, the reason for the 2w- 100k plate load resistors is to lesson the thermal noise. You are better off to leave those resistors alone unless they have drifted.

[@BenState]

citation?

[@moodyga40]

fabo vide Terry one of my most favorite amp to work on

[@johnblystone8781]

I like the OH camera. Thx

[@richardbrobeck2384]

I also use The M150 caps but stopped making some of the values I used rebuilding my old radios and audio gear Terry

[@countryguitar4u]

love your videos, can you recommend any books or videos to learn how to do this? thanks Terry.

[@electroKrunch]

?? Terry, I've got a Hakko 936 clone solder station (TekPower TP936D 40W maybe?). What tips do you suggest I have on hand for this type of work? It appears I can use the 900 series tips with this thing.... Soldering on heavier objects (pot backs & such) has always been an issue with the pencil tip it came with. Thoughts?

[@jdmccorful]

Good work!

[@electroKrunch]

Does the replacement of the .047u with the .022u caps mello the tone of the amp at all?

[@grindinglicks]

Great video

[@LitesLAB]

This was excellent Terry! I learned a bunch in this one and it was nice seeing some of the troubles you go through during the repairs! If I need advice for something I’m currently building, can I reach out to you? There are 2 areas I have some questions about. I can send a vid?

[@d-labelectronics]

Yes my friend, Happy to help

[@rheadelascy-wells6476]

I have a Fender Twin Reverb Reissue Blackface with a completely dead channel (normal). Back story, this thing blew its mains transformer, so it has new mains transformer, new filter caps and resistors, new set of tubes, but still dead normal channel. Ideas?

[@cjay2]

You're absolutely correct - those 100k's don't need to be 1W. Never thought of that before, but you're correct. The 1/2W 5% will do fine, with lower noise factor as well.

[@mikecamps7226]

to be more clear on the hot wire being switched and fused.....first order would be switch then fuse then to the transformer lead.....and since it has the auxiliary plug....that plug would be live all the time and not switched. SO considering who ever even uses that auxiliary plug.....it should be rendered out of circuit and dead.....and just there to fill the hole in the chassis unless you want to put in a cover for the hole and remove the plug completely

[@silasfatchett7380]

Higher power resistors create less Johnson noise. 1W is fine, 2W would be even better.

[@BenState]

@@silasfatchett7380 the difference is negligible at this temp and frequency.

[@lucianodebenedictis6014]

Don't you want to replace those wires? Every time there's arcing the insulation breakdown voltage goes down By the way I'm curious about that wire curled like a spring around another. Is that an half-assed shielding?

[@sting1111]

Terry vibrato is an Italian word pronounced vībrahtō. I love your channel. You teach me many things. I hope I don’t offend.

[@d-labelectronics]

Thank you Sir, No offense taken at all. Appreciate the input

[@cjay2]

@@d-labelectronics Just to be more explicit, because I don't know what the symbol lines mean on the i and o, the word in English is pronounced v-eye - brah - toh. In Italian it's pronounced vee - brah - toh. Just saying. Great video, great work and attention to detail. Bravo!

[@Davidjb37721]

Good job

[@bradbeasley7669]

excellent

[@steveh1273]

So what was going on with the bias circuit?

[@billbaxter2914]

Very nice.

[@mittman5331]

HI Terry, LOVE your channel, keep em coming and don't worry about all the trolls who've never even heated an iron complaining from their mother's basement. Anyway, the reason Fender used those big 1W plate resistors is because they ARE quiet compared with the 1/2 watt carbon comps. Same reason Matchless uses them in their amps. Those carbon comps have a very slight pleasing distortion (especially in spots where there is some current flowing) that is part of the vintage Fender sound. Great work as usual, love these videos!

[@sidbob169]

Here's a link to CC resistor distortion. www.geofex.com/article_folders/carbon_comp/carboncomp.htm

[@cjay2]

But as far as noise is concerned, those 1/2W metal films are much quieter than the carbon resistors.

[@mittman5331]

@@cjay2 Yes for sure. Just a different sound.

[@johnplaid648]

I grab my Kodak and take close up photos for future reference when I work on my PC.

[@emerson1978365]

Hi Terry, I am happy to talk with you. I have just a noob question , I hope not to be disturbing. ¿What kind/brand of video camera do you use for your videos?. Your camera just souns preety amazing to my ears, and your advice would be of great value to me because I work as a music teacher, and have the vide quality I need for making my video classes do to the quarrantine. Thank you for all your info, I am finishing my amp recently, and I always watch your videos searching for advice. God bless you.

[@d-labelectronics]

Hello, My camera is the Sony HDR-CX560V

[@emerson1978365]

@@d-labelectronics thank you so much!!!

[@waynegram8907]

Dlabs, what is so special about using those yellow Mallory M150 series caps? I don't get why you use the M150 series any reasons why?

[@p_mouse8676]

BTW, not ALL ceramic caps are bad. There are different types, and especially the C0G (NP0) are VERY temperature stable and often perform even better than certain film capacitors. They are probably difficult to get for these high voltages, but for low voltages it works great (and they are a lot cheaper)

[@cjay2]

The NPO's usually come in the small RF values, where the temp stability is needed. I don't think you'd see them in the .01uF range, especially in a guitar amp.

[@stepvanjoe3469]

"Do it right the third time", now that's a moto to steer clear of

[@Paul-ow6of]

Oh, nice Kenwood R-2000 Sitting over your shoulder.

[@d-labelectronics]

Yes Sir, just integrated it into the work bench

[@douro20]

Looks like the cover for the supply filter caps has been replaced.

[@d-labelectronics]

Yes, maybe the old one was arched up!

[@roberthurless4615]

Terry, i have seen the Techtronix 391A meter on Amazon for about $180.00. For about $20.00 more there is one that is calibrated and comes with a certificate. Do I need the calibrated model for tube amp work?

[@conjering]

YES

[@roberthurless4615]

Okay, thank you. Twenty bucks more isn’t much anyway.

[@shckltnebay]

If there is fair about of wax on the board shouldnt you suck the solder out of the hole before removing components?

[@xklopan]

Good thing you wasn’t touching that cover at the time of the issue!

[@daleburrell6273]

Why?

[@Retro.Studio]

Dale Burrell because of High Voltage transfer to grounded chassis parts. Imagine further when it hits it constantly plug in your guitar when having a pacemaker. You will get a inside meltdown or definitely cardiac arrhythmia.

[@daleburrell6273]

@@Retro.Studio THAT'S VERY UNLIKELY-!!!

[@Retro.Studio]

Dale Burrell with short debunking we have nothing, so tell us

[@geoepi321975]

Mr Carlson says that these yellow caps have polarity placement

[@geoepi321975]

@Hansel Franzen yes outside foil winding and inner side

[@brich2929]

he is right. The difference is very negligible, byt if you're anal about it, go test them first.

[@Jah_Rastafari_ORIG]

"Chocolate Drops"...? I've always called them 'Brown Turds'...

[@jimmusson]

me too.

[@jonathanhorne6503]

Me too. Were any of them leaking? I like the sound of the Mallory M-150 series but I also don’t like to just shotgun a board. The brown turds in my 1967 drip edge DLR are fine.

[@Retro.Studio]

jonathan horne interesting, can you explain what difference in sounds is with capacitors? If the value matches It getting particular voltages en pass it trough. the only thing i can inmagine is if they reliable or not.

[@jonathanhorne6503]

Retro4fun I’m not sure what dielectric is used in the brown turds. Mallory 150 polypropylene are great, DIY makers standard. Leaky caps, no matter the type sound like crap. It allows dc voltage on the grids, which effects the tube bias and sound, at worst it can burn up a good tube. In circuit measure the DC on the grid side of the cap and replace if more than a few 10ths of a volt.

[@Tonetwisters]

I think Terry is trying to be family oriented, perhaps, which is okay with me, in this world. Although, I understand the sentiment. As a guitarist, I would personally much rather some SoZos or Jupiters ...

[@jjsant3250]

Test the turds for value and leakage. I bet they are perfect.

[@dancoe4489]

Metal film resistors are much more quiet and hold value better, than the carbon composition resistors.

[@raulhernandez4300]

You added a current sense resistor, it's not a shunt resistor!

[@moodyga40]

the previous work looks catawampus

[@gerthalberg9735]

No Terry they don’t Call them chockolate drop caps, they call them Brown turds

[@MartynCole]

I'd have a panic attack if someone asked me fix something like that.

[@MadScientistGuitarLab]

After the easy fix you decided to change all those caps and drifty carbon resistors. I am really surprised you did that unless the owner wanted you to do that. Leaky caps and drifty resistors may have done so in a way that the player likes.

[@d-labelectronics]

Yes, owner requested

[@cjay2]

Leaky caps will blow out vacuum tubes. Drifty resistors can do the same. Both problems contribute to the death of the amplifier.

[@ptamp]

Why change the 3 caps in the oscillator circuit? there's no signal going through there. Besides maybe the little bit of microphonic in the disc caps in older amps is part of the mojo. I've noticed that old tweed solid core grid wires in the preamp are microphonic if you tap on them. Who says that's bad? I think it's part of the sound Change my mind.

[@d-labelectronics]

I perform the repair as requested by the owner

[@cjay2]

The oscillator caps are running between 1 and 10 Hz. There's no way that you'd hear any change in vibrato frequency in that range if those caps were microphonic. So it wouldn't be a part of the mojo.

[@Nirky]

Snow Pig says I'm first. :)

[@Texasbluestunes]

Dog TUUUURDS!

[@dwightjt]

What happened to the unger in this video? Hmhuhuhuhyahhyahyhahyahyehyahyalyakyak

[@MikeJones-ro5nl]

"vibRAYtoe"? No it's "vibRAHToe"

[@patrickmay9034]

...let's call the whole thing off

[@tonystephen6312]

Americans often say vibraytoe - doesnt matter really!

[@silasfatchett7380]

If you are going to call the effect by the wrong name (it's tremolo, not vibrato) you may as well pronounce it incorrectly. (Not you personally, people in general.)

[@Tonetwisters]

Well. My apologies, but I'm about to quit KZbin because of all the lying Biden ads.

[@silasfatchett7380]

'Bye.

[@grindinglicks]

Great video