How to fix troubleshoot Fender Twin Reverb tube guitar amp Noise Buzz

Part 2. Repairing the Fender Twin Reverb from hiss, buzz, noise distortion. These amps have been in service over 50 years, therefore they will develop bad connections, corrosion, weak leaky components. All contribute to poor performance. This video will assist you to establish a common sense approach to isolating the typical failure areas. Thanks for sticking with me as I grow the D-lab channel. It has been a long journey, but worth it. TD

[@rickshaw6228]

Great listening to you! I was an ET in the Navy and now build and repair amps. Very good information and easy to follow.

[@rickcostin]

The green goo is a lubricant they use when manufacturing the wires, I'm a 240v sparky in Australia and have seen this on old PVC cables used in house wiring in the 70"s. You can clean it off but it's in the cable and will ooze out again, suspect it's non corrosive but just makes a mess. Thanks for the video's by the way very informative thanks Terry.

[@rickcostin]

From something found on the web, not too sure of the accuracy of this because I've found this green substance on cable you would not expect to have had any overheating such as lighting circuits, non toxic but then it goes on to say wear gloves when dealing with it...? Now and then on a job you may come across twin and earth cable that is oozing a strange green goo-like substance, almost like washing up liquid. The wet green liquid that you are seeing is the product of a reaction between decomposing plasticiser (a plasticiser is an oily liquid used in the manufacture of PVC compounds) and the copper conductors of PVC cables. It’s better known as cable ‘greening’. The decomposition of the plasticiser is caused by overheating the PVC compound. It is usually a slow process, but can be accelerated when high temperatures are involved. High temperatures can be caused by external reasons, but overloading and loose connections are two common examples. Although all cable grades of PVC may look the same, the cheaper grades can be more prone to producing the green goo. The main instances of ‘greening’ cable arose during the 1960’s and 1970’s, although some instances are still seen today. Inferior grades of plasticiser were prone to greening even if the cables were not overheated. The plasticiser of better grades of cable, such as those produced by Prysmian contain an antioxidant which inhibits the decomposition rate of the plasticiser when heated. Even these plasticisers can be broken down eventually under adverse conditions of heat, but are much better protected than those which do not contain an antioxidant. Although fumes may be given off when PVC is decomposing (this statement is applied to house wiring) it would not be considered to be a health hazard, but there is a danger that the breakdown of a cable could cause an electrical fire. The plasticiser itself is a clear oily liquid that is non-conductive. The green substance is a combination of copper oxide and plasticiser which is conductive. Therefore, whenever this green substance is found at socket outlets etc. it should be removed and the terminations cleaned (gloves should be worn) otherwise it is possible that tracking/overheating may occur. It is normally considered that if greening is found that rewiring should strongly be considered. If, however, it is considered that rewiring is not required and the effect on decoration and equipment is acceptable then the following actions are advised: Periodic inspection and testing is carried out Visual inspection of cable ends, equipment and cleaning/replacement is carried out as required That the resistance of conductors is monitored to ascertain that conductors are not being over oxidised (in parts of the cable that cannot be seen) and their resistance thereby increasing The question of how frequent inspection and testing should be carried out is a good one, but no established guidance exists. Therefore, only by experience of the particular installation concerned can the frequency of periodic inspection and testing be determined.

[@pezinski01]

D-lab productions, probably the best in the world

[@crazyuncleduke8012]

Oh how I remember those CBS era silver face Fender amps. They spent more time in the shop being repaired than being played through. :-)

[@remley8877]

Great video. Love the opening music too.

[@evananderson8452]

You're very good at what you do.

[@finnsuchara1992]

Usually thermal stressed are to blame for throws connections on the diodes, not vibration. love your vids, i would like to see more stereo amps, or test equipment related videos though.

[@ronnielobosmith4870]

Dude you're educational and funny totally rad channel man I dig it

[@Starcrunch72]

Terry, watching this video again and you mentioned Watts Audio--well that guy's shop is dead after some nefarious issues. So to redirect people to a better vendor 2 years later, I have used Doug Hoffman at Hoffman Amps for replacement eyelet/turret boards. He also runs/owns the el34 world amp forum. Just an update in March 2020.

[@thomascowan1825]

Very impressed Terry. I learn so much info from your description clearity. I wish I could get my amps to you. All of them need so much work. I'm just trying to preserve what they should be when they were new. Our techs seem to think, oh that's good enough state of mind, but that's not good enough for me. I can't even get descent test equipment here in CANADA and no one knows how to use it. Very frustrating. I'm sorry, didn't mean to complain.

[@scottmeacham937]

I understand your sentiment. I too have had some meh experiences with local techs up here in the Great White North so I taught myself how to. I've successively repaired all my amps needing it, done many mods to circuits now to suit my needs, done troubleshooting on several amps, and now built several amps from scratch and have also done some fun retrofits too. If you are in the Vancouver area and need some amp service done , message me. I insist on a perfectly operational amplifier and a satisfied customer. I even do radios too! I credit Terry here at D-Lab, Uncle Doug and Brad the Guitologist too, I've learned so much from their youtube channels; also trial and error, that's how you learn.

[@sparksblack]

This was excellent, thank you.

[@matthewf1979]

Replacement eyelet boards are the way to go on later Silverface amps. You can populate them with new components for under $50, including the filter cap board. A few hours later and you got a basically new amp that’s reliable and sounds great!

[@d-labelectronics]

Yes Sir, I will have to discuss with the owner and see if he wants to invest into it.

[@AliKiani7887]

Thanks Terry , so nice video, its awesome...

[@ewerton8463]

you're the walter white of electronics

[@shaftbox]

Hi Terry in the UK we had a problem with late 60’s early 70’s cables used in house wiring oozing dark green sticky goo, it is a problem with the plasticicer used in the PVC sheath on the cables it runs down the inner space between the insulation and the copper core we can leave it if found it’s not conductive or corrosive just really messy maybe it’s a similar thing you have, love watching your videos Mike

[@d-labelectronics]

Hi Mike, Great info. Yes, that sounds like whats going on. The green goo, only appears at connections where wires land. So, I think you nailed it. Thanks for commenting.

[@whatyoumakeofit6635]

Thanks great onfo. Amazing how youtube connects people across the world too share knowledge like that. Thanks

[@smstiao-tecnologia]

Hi Tery, one more nice job !

[@normjacques6853]

When you're poking around (I use a chopstick instead of a tuning instrument) try using a speaker instead of a dummy load. You'd be surprised at which components can act 'microphonic!'

[@burrmanchu687]

This guy is awesome.

[@jayybone6227]

Right on

[@billdyke9745]

That green goo? Ectoplasm. Probably the spirit of Leo Fender trying to tell you something... Black magic, man...

[@jorgemellooliveira9611]

ótimo trabalho congratulações

[@valentinafernandez1119]

Very good video! I also have a 70s twin and it has a strange problem, when I turn it on it works great, but after it heats up, if you turn up the volume of both the pre and master to 10, you notice that it has a pot noise when dirty and you move it. It seems to have the problem in some component that channel 1 and channel 2 share, because if I leave channel 1 at 0 and change channel 2 to 10, the noise starts. If I reverse the volumes, the noise can also be felt, but on channel 1 it is much more noticeable, like 80% on channel 1 and 20% on channel 2. Thank you very much in advance and sorry for the inconvenience.

[@packdawgs]

I haven't even watched past the open and I've subscribed because of that sweet music. What is it?

[@stevensalt2471]

We get a lot of green goo in domestic wiring in the uk. it is caused by a reaction a reaction between decomposing plasticiser and the copper conductors of PVC cables. The only problem it will cause is to the switching mechanism or other mechanical devices. Don't believe it will damage the circuit devices.

[@kenhancock8931]

FIRST thx terry exellent as always!!! ;-)

[@warioblast]

That intro music is really spooky.

[@rciancia]

I've fixed a bunch of these and also have seen the green goop... it is exactly what you stated. Not sure if it was glyptol or just a paint/dye of some sort. Either way, No Bueno !! Nice sleuthing job as usual ! Ron

[@d-labelectronics]

Thanks man, I plan to contact the owner and see if he wants the amp as it is now or if he'd rather have a new eyelet board installed, all new wire, etc. That would be costly and eats lots of shop hours. Hope your 2E26 build is going well.

[@rciancia]

Thanks Terry... I finished the build and now am lead dressing and throwing the scope-a-ramus on there to start checking things out. A quick test shows alot of gain, almost too much.. so honing in to that area.. ( this is a dual 6AQ5 build). All to be covered in the next video. Good stuff as always on the DLAB channel !!

[@paulumbriaco9247]

How about a video about checking a fixed bias twin amp to be sure it is operating correctly.

[@Tonetwisters]

I own a 1976 Twin Reverb Amp which I have had for several years. It was last worked on by a nationally known amp tech, and sounds as technically "right" as an amp should sound. However, these amps (blackfaced and all) tend to sound very sterile, as they are very clear, clean amps. I think the next tech who gets a hold of it, will "warm" it up a bit, as he is able ...

[@cgavin1]

A lot of those amps are usually biased badly. On the later fixed bias they are often biased very cold. You can fix that easily! I have a 1977 that has not been modified other than replacing the filter caps and electolytics. Its the much loathed ultralinear model. It has TONS of character and sounds great. A huge part of getting good tone out of a Fender twin is knowing how to use the EQ (because of the way the circuit is put together its all interactive). The old "666" setting is the best I find. 6 vol, 6 tone, 3 mid, 3 bass, 3 reverb 3 master vol. Do this for both channels even if like most people you don't use the normal channel. The two channels are also interactive. The second biggest factor is the speakers. You'll definitely want some modern 75w Eminence Legend 1258's. HUGE improvement in midrange and bottom end. I also strongly recommend using higher gain 12ax7's like JJECC83S. You can actually get some grit using the above channel vol on 6 and that EQ with a humbucker with the MV on 3. I can honestly say that my amp sounds anything but sterile! PS: Its very important to actually use the hum balance pot to get your output tube voltage matched. You get a lot of noise if you don't (especially if you use unmatched tubes) and the amp can get mushy and flubby.

[@EternallyRound]

The green goo may be contact cleaner that someone sprayed into the input plugs.

[@pneumatic00]

Think there's the possibility that the green goo is the remnants of some acid flux solder? Maybe the previous tweaker didn't load up on acid core solder, but used his iron accidentally on purpose using the wrong kind of solder. (acid + copper = green) I've seen that green goo before. I hear ya that it could be an inspection thing, with a dab of paint, but I don't think that's what it is/was; first, it was only on a few solder joints, second, it was still wet. My vote: acid core solder residue on whatever soldering iron did those joints. Nice video, Terry!

[@stevensantos369]

pneumatic00 that was my initial and immediate assessment as well.

[@rickcostin]

Not really sure about the accuracy of this info from the web , If true there would be a lot of rewiring of 1970 houses especially the part about fire risks, I recon I did question the toxicity of this substance at the time when I was working with it regularly but got no answers at the time. "The plasticiser itself is a clear oily liquid that is non-conductive. The green substance is a combination of copper oxide and plasticiser which is conductive. Therefore, whenever this green substance is found at socket outlets etc. it should be removed and the terminations cleaned (gloves should be worn) otherwise it is possible that tracking/overheating may occur. It is normally considered that if greening is found that rewiring should strongly be considered. "

[@jonathanhorne6503]

I seen that same green goo on silverface fenders. Never on black or Brownface amps. The silverface amps used different wire with a vinyl insulation. I don’t know for sure what it is.

[@TheGalaxyhopper]

too cool.

[@fmercer54]

That was Awsome, good health ....😜🍷

[@Banjoandguns]

How do you feel about me using a variac As a attenuator on a fender twin. I bring it down to about 85v

[@sauerdrops484]

I love my Luxo too :-)

[@dhpbear2]

3:19 - Oh boy! Leo got a pretty good deal on white hook-up wire back then :)

[@irieanimalcare2736]

Leo wasn’t around for this crap...

[@damianstrochnetter9735]

Right, right, right, right.....

[@sting1111]

Ya those boards take on moisture and warp thereby breaking connections.

[@taejun9017]

Hi I have a twin reverb that was smoking as you described, I applied red wine but it didn't seem to fix the issue, the smoke actually increased. I was wondering maybe since I used Merlot could that be the problem, maybe a cab or pinot instead? Any help here is appreciated!

[@videolabguy]

GC chemicals company is or was the number one site on the federal toxic clean up list many years ago. It was also a related company of Jerrold antennas and JFD manufacturing. Nothing will ever grow on their site again. In high school I worked for a fellow who used a GC "rubber restorer" product on tape recorders and turn tables. If he simply opened the bottle in the shop, I was sick for a week. Can taste it as I type this. He died a horrible death of cancer. If it is says GC on the bottle, I give it a very wide berth!!!! I can't believe they are still in business! They have killed more people than world war III!

[@CaffeineInjected]

Wow that looks like a tough job. Can i send you my 79 twin reverb. It needs work! I'm serious too.

[@O.W_Films]

Green goo is old soldering paste, when you solder long enough you see them on old pipes or electronics.

[@renegade44040]

With all the green goo and wax how did a Fender Twin become a highly sought after amp?

[@cuztomaudio810]

Have you worked on the Fender Twin Reverb reissue? The one with the PCB.

[@raoulduke806]

BTW is this an ultralinear 135w twin ?

[@oelcudildiego5057]

Goodevening....i have question.....i have a Fender Quad Reverb My Capacitor Mallory 25uf 25v has been damage... what capacitor and what value of UF and value of Volts of the capacitor i replace to the orginal capacitor( Mallory 25uf 25v)... Thank you Very much...😊

[@gillamb8669]

Hi Terry. I’ve searched for the schematic for this model & don’t find it. I found 4 different schematics and layouts that don’t resemble mine. This one is exactly the one I have. Do you remember which schematic this one is, and where can I find it? Thanks.

[@luthiervandros]

I’ve got a 76 ultralinear 135 on my bench. Gah. The wax is from heat in some cases.

[@k9wyre]

Terry, Do you accept donations of used tube amplifiers to feature in your videos. I’m a new subscriber and love your videos. Very educational and entertaining.

[@d-labelectronics]

Hello, Yes Sir, always welcome. I love featuring the odd balls. Be glad to repair it or retro fit, with a KZbin vid for all to enjoy

[@raoulduke806]

how is your guitar learning endeavour doing ?

[@Tonetwisters]

The thing to do, is not just make these amps serviceable, but make them sound like they have some personality, some warmth and the kind of tone you can't wait to plug into and flip on, rather than just a "loud machine." In other words, look for components you can switch out that bring life to them that is better than what CBS intended. Just because Leo or CBS made them, doesn't mean they are as good as they could/should be. I have one of these amps and I never turn it on because it has no life to it. And that's coming from a player of 57+ years ...

[@dhpbear2]

I assume the amp still has the 50mV hum?

[@Wizzle]

I can't find Part 1, help?

[@JustinHallPlus]

My 71 ywin reverb has low volume and a buzz even with the volume at 0. can you help me troubleshoot? I think the bias caps are okay, reading 51 v and 62 v when the amp is on. On the second blue ugly cap from the end it starts at about 400 volts and then starts dropping as the hum gets louder. Any ideas? the amp still amplifies, but it's like theres a resistor pulling an input to ground somewhere.

[@fredguitarman3536]

Sounds like the filter caps inside the doghouse drying out

[@daveogarf]

PROPS for "resistoroid"!

[@roberthurless3295]

Hi Terry, where do you get you GC Isopropyl alcohol from? CE doesn't carry it.

[@d-labelectronics]

I used to buy it thru MCM electronics. I believe now it is packaged as a Tenma brand, buy it is 100%

[@pneumatic00]

Isopropyl alcohol actually can not get stronger than 91% (the rest is water) unless fairly expensive chemical treatment (beyond simple distillation) is used because it forms an azeotrope and can't be distilled any stronger. You can buy 91% isopropyl at any drug store, just be sure it is the 91% and not the 70%. The 91% costs more than the 70%. The 91% is fine for flux removal. If I was cleaning tape heads, I would probably insist on 99.8%, it will be much more expensive.

[@brich2929]

Terry, any insight on what is going on with Watts Tube Audio? Also, what's your alternative since it looks like he isn't in business anymore

[@d-labelectronics]

Hey man, I will see if I can contact him. It's been a while since I've ordered

[@driftertravelerman6893]

Yeah ive had this one under a blanket in a closet for the last 28 years i guess, It hums and my dad messed with the wire and it made the buzzing worse.

[@exciter2506]

Terry, you look like a Dentist. I would still rather have you work on my amp than my teeth.

[@patrickmay9034]

And keep away from those Cesna's .

[@RobertKohut]

Nice job!! No kiddin'...LOL

[@kornami8678]

Green nail polish?

[@giwrgoshai9715]

I have a very old fender booster and when i try to open it it doesn't work

[@jedhatcher252]

Mine has all the sudden started to have a hum noise that is pissing me off.

[@dhpbear2]

Fender should have used green FLUX instead! :)

[@johnbellas490]

Hello Terry!! Good video as always !! The green goo, I wonder if its acidic or alkaline? Do you have any pH test strips? maybe next time you come across this stuff you might be able to do a pH test on the green slime? I am just curious. John Bellas KC2UVN

[@whicks24]

My first thought on seeing the green goo was, "...somebody used expired anti-sabotage enamel or flux". It would be very interesting to know the pH (said in an Arte Johnson voice).

[@kendavis8046]

And you have to be of the same vintage as both Terry and me to even understand the Arte Johnson reference! Thx.

[@johnbellas490]

I remember the show and Arte Johnson's portrayal of the German WW2 officer, but never watched the show much. Yes I remember --------- VEERRRRRY INTERESTINNNNGG !!!

[@lightshadows1997]

I have the same amp. It needs some attention! Can I have you fix it for me? Seriously!

[@richpiccerillo2301]

I have a fender red knob" the twin"( 100 watt )amp what's up the volume control it's more like an on off switch I can't use it cause its to sensitive what do you recommend .What kind of vol pot should I get that's not as touchy .and or should I just invest in an aattenutor

[@stevensantos369]

Rich Piccerillo I don't know anyone who has a twin 70s silverface...but some of you may not know that the master volume has a 2nd feature. It will pull out for extra gain or distortion. That may be your problem. Iam not sure what a red knob has.

[@RobertKohut]

Ecto Plasm...who you gonna call?

[@markankarbergwork]

UNCLE DOUG CAN YOU PLEASE BUILD A 135 WATT FENDER TWIN 1973-1975 MASTER ( NO MASTER ) BEST EYE LET BEST PRE AMP TUBES BEST CLEAN POWER TUBES RCA 7539 ,RCA 7522 ,RCA 7526 RCA 7522 POWER 6L6 ? .BEST POWER TRANSFORMER BEST POINT TO POINT WIRE ECT SPEAKER JBL D 130 f .15 inch .ALL NEW ALL BEST DOUG CAN DO . THANK YOU , DOUG .

[@DeDeNoM]

So the D in D-lab is for dental?

[@mikeferris408]

Ya, my brand new twinreverb starts out with a feedback sound that creeps in as soon as i takenit off standby n gets louder n louder n so on.. it does it with or with out anything plugged into it. Dam near at 2 grand this fender amp should definitely not be doing this! Ya... im pretty pissed off.

[@kornami8678]

Put on your white lab coat or smock and we'll call you Dr. Terry.

[@stevebrown4085]

Dentist - smentish a neurosurgeon!

[@Badhands55]

It would cost more to repair than it is worth

[@dhpbear2]

8:30 - As much as I love the oscillatin' television, a speaker would work better for this :)

[@jakobsaternus3526]

This is the sound he's feeding into the amp: kzbin.info/www/bejne/ZpjKhoOmeqd3bNU

[@barbmelle3136]

From Leo: Looks like someone used plumbers acid flux when soldering.

[@freecitizen2760]

I like these old amps because I learn by working on them. If you don't want to spend time and money doing this, buy a reproduction.

[@willywong3243]

Please text me if you can Thanks

[@Turboy65]

Don't let somebody service your amp if he refers to resistors as "resistoroids".

[@billdyke9745]

That green goo? Ectoplasm. Probably the spirit of Leo Fender trying to tell you something... Black magic, man...