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

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.

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.

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

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.

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

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.

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 !!

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.

pneumatic00 that was my initial and immediate assessment as well.

Leo wasn’t around for this crap...

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

Sounds like the filter caps inside the doghouse drying out

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

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.

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

And keep away from those Cesna's .

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).

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

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 !!!

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.

This is the sound he's feeding into the amp: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-0ggUPpEBD6s.html