PROOF the RUSSIANS RIGGED this Guitar Rig!

This Sovtek MIG-50 head had several issues. The pots on these are crappy and need replaced, the caps are still original and it's time for those to go, the owner claimed Channel 2 wasn't working so we'll check that out, and we find some surprise issues with the bias circuit that cause the 5881 output tubes to red plate. At the end we'll demo this little monster with a 1970s Jolana Iris and a 1989 Charvel 750XL. Good times all around.
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[@TheGuitologist]

I just realized I left out an entire section of this repair... I found some old Sovtek MIG knobs in my parts stash from a different MIG I had a while back. I drilled them out and gave this amp a full compliment of original MIG knobs. I filmed that part but forgot about it in editing. Oops. Oh well.

[@TheGuitologist]

hahaha....yeah, it's the curse of the observant to be confused by my videos. :P

[@kabali1788]

Just shut up and play your guitar ( through the well repaired amp :) )

[@psychoticmemories2583]

You can always upload it again with the left out section included and call it PROOF the RUSSIANS RIGGED this Guitar Rig! - UNREDACTED!!

[@TheGuitologist]

The caps probably weigh more than any other component on the board, so they have the most inertia. If the amp is jostled, they may threaten to break the solder connections on the underside of the board. Those traces are fragile and it's best to do what you can to keep that from happening. Increases long-term reliability. Also, you'll notice I did not de-solder the original leads, but instead clipped them off the old caps and soldered the new caps to those. That kept me from having to disturb the traces on the board also. Too much iron heat and those can just call apart on you.

[@green323turbo]

Freddy Y, hot melt glue .. ( not silicone) ?

[@TheMtvdeath]

These amps were made in my hometown called Saratov (inscription under input holes says "Made in Russia, Saratov") =)

[@TheGuitologist]

Very cool. They've made your town famous.

[@AbsoluteRecoil]

In russian slang "Sarai" translates to shithole; so the fact that the prefix of the named city is pronounced that way it made that shithole very special!

[@joshuamauk6759]

Do you know the translation for the red script word on the Sovtek Mig 60 amps?

[@robertsmiczsmiczamplificat593]

Aleksey Chernozubkin i loved those amps brother. I sold at least 100 of them. I used to mod them and sell them. They ripped. I wish we could still get them.

[@evetsnitram8866]

Love the Russian amps, effects and synths. Its also cool to see a tech guy that can play!

[@gmccrarygm]

better than most instructional "how to" videos I've seen in a long time...props on your playing as well. some of us non-book learnin types really pick up quite a bit more info that is usefull by watching a master at his craft rather than sitting in a class listening to some necktie ramble on for hours. very informative and has qued my curiosity wich will promt me to definately watch alot more of your vids..thanks!

[@MAXIMUMintheHORMONE]

"All of the pots are shit", No truer words have ever been spoken.

[@OutLoudOutLoud]

DeoxIT, comrade. DeoxIT.

[@tims001]

Yeah mine are shit on my mig 50, the whole thing needs to be overhauled

[@joshuabloodsworth9495]

@@OutLoudOutLoud deoxit cant save a shitass pot

[@vargasjj510]

Wow, great details in this break down, and repair. I'm sure that was one more happy customer!, and we happy viewers, thank you for the slow rig down with so much details. I learned a lot. And the dive bomb w/o whammy bar was hilarious :D

[@rich227742]

You don't only know your shit about amps you can play also, very smooth playing

[@TheGuitologist]

Thanks, Rich.

[@SPINNINGMYWHEELS777]

one would hope those talking on youtube would have experience.

[@B3Band]

Why would someone talking about electronics repair need experience as a musician? Are you good at repairing amps? Maybe you shouldn't be playing guitar, then. Your logic.

[@B3Band]

Yeah, man, the way he hit those 5th and 7th frets on every string was badass...

[@DigBipper188]

In Mother russia, you don't fix amplifier. Amplifier fixes you.

[@andrewwagner6851]

I do not want castrated

[@terrypussypower]

@@andrewwagner6851. I do not want Novichoked!! 🤪

[@axelavila4816]

I’ve just got my own mig 50, I’ll take into consideration all theses suggestions. Thanks for uploading very very useful !

[@user-bl1yn5kt9n]

No L! And you'll never hear me correct about pronouncing again. Because I'm a working man from AL. Dang!! I love your work. The way you talk us through, while showing hands on, is great for me! Thank you brother.

[@DeadKoby]

In mother Russia, Guitar amps plays YOU.

[@debroahcain5191]

DeadKoby the father land make better amps

[@debroahcain5191]

DeadKoby some people make clones in America ten times better look up mega tone amp it small amp builder

[@DeadKoby]

I wouldn't doubt it. Sovtek Amps was Electro Harmonix kicking around getting into the amp biz. I figure they have such a big stake in the Reflektor tube plant... why not try.

[@umajunkcollector]

Fender and Marshall copy Rooshki amplifier

[@bytwyzz]

KRYPTONITE TUBES !

[@TheGuitologist]

Thanks for the comments...I actually have a bunch of phenolic sheets lying around, just wasn't sure what to call them. Thanks.

[@richardturk7162]

I had a 92 Mig 60 and it was a great sounding amp. Great video again Brad.

[@vmat1000]

i was always curious about these amps in the '90s but never heard or played thru one. This repair turned out great.

[@alvagoldbook2]

Back in the 90's, I always wanted to get one of these. I came so close to getting one, but never ended up pulling the trigger. Despite their fairly poor construction, the circuits are pretty cool and placed in a nice package. it's cool that the Tube Midget was so ahead of it's time, and paved the way for all the little lunch box amps we know today.

[@mikebuchanan-fatdaddysfine7513]

I've had one for 20 years. Still works and sounds great. Granted it sat under a sheet for over a decade. Broke it out in March and with a few pedals it gets the job done still....

[@chrismoore7359]

With the nation on lockdown its been such a pleasure watching your vids - one after another! Your content is highly addictive making me fear the impending doom of withdrawal once the pandemic is over. I'd dumpster dive with you any day brother!

[@jonlennon3348]

That brown board is phenolic resin impregnated cloth and they use it for varied purpose's such as a insulator etc.

[@akc5150]

Also the often sort after and very misunderstood material that was used on the neck pickup of Eddie Van Halens original Frankenstrat.

[@joelgrigsby96]

jon lennon Micarta is what it's commonly called.

[@Rob-ec8xv]

Yup. It's called micarta. We use it in the tool and die industry as an insulator between high voltage components and ground, or other tools. Usually welding equipment. It's hard, robust, and non conductive. It can also take high clamping force from fasteners without being crushed. They also make micarta washers and hollow rod to insulate screws and bolts from said energized equipment.

[@Paul-gz5dp]

On the board too much brown is carbon and does lead to a short circuit. I have found that a sand blaster with glass beads is a good thing to have when repairing equipment, as it allows removal of burn marks on boards so they can be repaired. Also after done cleaning such boards it helps to spray them with glyptal lacquer, and use the clear stuff on circuit boards. That is because it helps make them like new after they have been damaged and this is the only way those boards are easily repaired when a new one is not a possibility.

[@magicmaui77]

We call it Pertinax

[@offdutyjie]

You're a genius man! I've been wanting to get one for a while and you have a perfect video here taking a look at it lol!

[@JobyP]

Man.... I LOVE those Migs. That amp + anything Mahogany with a P90 in it = Rock and Roll! Great video!

[@TheGuitologist]

I had an LP Jr. just off camera. Mahogany and P90. Guess I shoulda grabbed it.

[@JobyP]

Yeah I love that Jr of yours....

[@mikkatuka3479]

Yeah, now go to gulag

[@davidallen346]

It did sound good after the repair I'm impressed

[@De4thInc4rn4te16]

@@beelbug2396 got a link?

[@Ezekiel33USA]

You do a very good job with this channel. You explain what your are doing and why you are doing it very well, plus you demonstrate the results very well too. I used to be an Electronic Technician in the Navy over 20 years ago and I haven't been involved in electronics in a very long time, but watching your channel has given me the bug to start getting back into it. I play guitar as well, so I might get into amp building. Unfortunately my electronics skills are very rusty, but you have given me the itch to dust them off. Thanks for what you do.

[@TheGuitologist]

I LOVE comments like this! I do hope you get back into the swing of things and remain interested. Go on Craiglist and find yourself a fixer-upper amp and dig in! A lot of times you can also find stuff in the CL free section for repair. Pick up an old console tube stereo amp or old organ and get your tinker on that way too. When you get up and going, make a KZbin video and link back here so we can see your progress.

[@nickd3593]

Really enjoying your videos man. Love the whole trouble shooting journey. Keep 'em coming !

[@JesusIsLordofMybeing]

As always Brad, Awesome work!!! Thank you so much for your guidance!! You ROCK BRO!!!!!! \m/

[@Incommensurate]

I love you you drop all this knowledge on tube amps and then play your ass off at the end

[@iantheorem]

You make really good videos, your well spoken, very knowledgeable and an all around cool guy! Any haters can bite it.

[@joearrue6819]

That amp sounds incredible! I´m always amazed at your skills man! i dont know 1/10 of the things you are mentioning but I keep watching (maybe ill learn by watching you haha)

[@thomasdoyle4485]

sounds good.... The material you pointed out inside the open transformer ends is a phenolic insulator. They use the same material in High Voltage 3 phase switch gear breakers between the phases.

[@johnthrelfall5]

Excellent troubleshoot , refurb & maintenance work!

[@TheGuitologist]

Thanks, John.

[@williamhill6705]

nice work,, its a few years ago i see that , but still good entertaining material, its got to be the most satisfying thing to trace and fix an awesome vintage piece of kit like that then put it through hoops ,sounded damn cool,!

[@Dan79istheman]

Great work Brad! Love your playing too...

[@TheGuitologist]

Thanks, Dan, as always. Good to hear from you.

[@scottson2]

Great video series BTW, i am learning a lot. QQ, for those large capacitors you replaced, did you just cut the old ones out and solder the ends to the old posts or did you completely remove them from the old board? I am currently trying to fix my fender red knob amp and would like learn some best practices... thanks..

[@charlesshaw9090]

Cool vid again. Love your playing. The fault was a bad connection on the bias diode. When it made contact you got the correct negative bias so the anode currents were correct. When it lost contact then the bias would be 0V dc causing huge anode currents which in turn caused the B+ to drop. Must be a pretty good power transformer because a lesser one would have dropped its voltage much quicker! This amp is a good example of why there should always be a correctly rated slow-blow fuse in the B+, for this amp T500mA.

[@jontallbacka9406]

excellent repair and likewise on the shreddin' - Keep safe and keep them videos commin'

[@kardRatzinger]

Nice Jolana, I have one myself, different model same tremolo unit. I was wondering about the preamp tubes in this - are they really 12AX7 or 6N2P?

[@marsmediapro]

I have just recently discovered your channel, beginning with the Marshall head found in the trash! I enjoy your repair videos- well done! When you change components out, like pots, caps, etc- do you rewrite the schematic to reflect any value changes?

[@skipsterz]

I still got a Sovtek MIG 100h. I had some minor issues with it over the years but for the price, it was well worth it. The 1/4" in/out jacks are crap and my bass pot did very little from new. Also had a noise issue that was related to the fact that it was "mishandled" during original transport, that caused the same one 5881 and fuses to blow. The amp tech pointed out the minor damage and was easily fixed. Currently going strong but Its had a bad high input jack for many years that I need to get around fixing. I just don't play it anymore. Good to see that other Sovteks are still kickin'.

[@matthewf1979]

What was the final plate voltage with the -77 grid vdc? The Sovtek 5881's are a 6L6GC internally, they can handle a few more than 19 watts PD. Those Mig 50's are pretty awesome amps. They basically slammed a 2204 and 5F6-A(with circuit revisions even) together, jacked up the juice and sold it for a price anyone could afford. (Wait a minute.....they just modded a 5F6A in reality🎸🤘) Regarding the transformers, I think the manufacturer only had tooling for one style bell for multiple transformers and filled the ends with material that's easy to cut/shape. Remember, we're talking about Russia here. The home of the stamped sheet metal assault rifles and hard liquor made from potatoes. Their shit just works. Another great video! Thanks!

[@TheGuitologist]

Plate voltage was about 525V. I didn't want to push the 5881 too hard. At this bias, they should last a long, long time in this amp. And it's still loud as piss.

[@TheGuitologist]

...and you're right about Russian engineering. Their military spec hardware is usually excellent. If it ain't broke, don't fix it. That was their motto. Well, that and "death to capitalist pig dogs". :P

[@bremsnix]

Yes, what they built out of metal usually was rock solid. My dad always tells this joke about Russian engineering: Do you know how Russians build a railroad engine? They take a huge block of metal and just cut away everything that doesn't belong there.

[@gbowne1]

Their shuttle still exists but its rather dusty lol :)

[@russellhltn1396]

I'm thinking the manufacturer didn't have the equipment to stamp out the cupped metal ends we're used to. Or perhaps that equipment had higher priority jobs. The ends shown there just need one of those metal benders.

[@GrafStorm]

I have a Mig100 Sovtek made in Petersberg Russia. I've played it for years gigging in the US. Replaced the original tubes w/ Chinese "Sovtek" tubes purchased in the US. Never had any problems, used also in the studio for recording. This amp is a monster for those who are able to play, it delivers powerful tone and is loud. You must be able to properly set your system, just like any good 100W head, like a Marshall, etc. I love my Mig100 with the original 4x12 cab, I've had this as my main rig since 1998. Sovtek rocks!

[@lDNASTYl]

I've been a sub for a while I'm just mainly a diy guy. I don't know if you've done like lesson style videos before to teach people like basics for amp repair but I think that would be really awesome I for one would love to learn more. Anyway thanks for the vids keep em comin!

[@TheGuitologist]

Thanks for the encouragement. I could not do a better job than Uncle Doug. I encourage you to sub his channel for more basic instruction. kzbin.info

[@lDNASTYl]

thanks i havent heard of his channel but i will check it out thanks again

[@jonathanbelzley2877]

Thanks to KZbin, I now have an Uncle Doug, an Uncle Ben and a Guitologist. Thanks for the videos! I'm learning a lot.

[@RATTL3R186]

Fiber glass board is called phenolic,non-conductive etc. Was used by hot rodders back in the day to make carb spacers. Also used in tool and die work at times.

[@earthianfriendly5708]

Should it be pronounced "Soviet technology or Sovtek in short"

[@weedislegal4me2]

The fiberglass plates in the transformer you mentioned, are phenolic plates for heat dissipation.

[@domdingle311]

This amp is one with The Schwartz and so are you my friend ... great playing , tone and overall vid \m/

[@DaveFreyJr]

I just love your channel..i hope to have a youtube chanell one day..very informative, fun, instructional vdeos. Thank you Brad the guitlogist.

[@TheGuitologist]

Thanks for watching!

[@markholt2395]

I've had my mig50 since 95, and I have not needed to replace anything til just this year. Still love this thing as It takes pedals amazingly.

[@MrBeblis]

Another great video, my question is regarding that whitish substance you are using between the caps you raplaced, what is that and can silicone be used as well?

[@alexandrnikiti5895]

Good video! By the way how does charvel xl 750 compares sound wise to les paul? Is it somehow similar? How do you like that guitar is it as good as people are saying. I have a chance to buy one. Thanks

[@DreamWeaver3112]

Awsome vids,Great info,loved your intro joke,I swear I voted :O on one of those. Have you done in the past or maybe might see in the future a Soldano head? peace.

[@TheGuitologist]

Never so much as cracked open a Soldano. I've played through one or two before. Maybe one day we'll get to check one out here.

[@williambock1821]

Had the same problem with a Traynor YBA-4. The replaced bridge rectifier wasn’t rated high enough. When pressing on the board ,the current limiter would go out but when lifting up on it(with chopstick) the light would come on. Replaced with bridge rectifier made of discrete 3A rated diodes. Fixed.

[@johnstanley6977]

People like you give me hope for the future of guitars.

[@kinx001]

I really like the tone you got from that guitar/amp/speaker cab combination t ! I'm from Czech Republic and I grew up around these Jolana guitars, since they were the cheapest solidbodies for begginers to get when I started to play guitar (late 90s). I never liked them at the time, but they kinda grew on me. Do you have any mods / tips for this model? I only remember appaling vibrato/bridge system, frets that didn't last even looking at them and horrible open back tuners

[@jetteroheller]

Can’t even imagine what kind of list I’d show up on trying to get parts for this thing.

[@barrymccarus6982]

Amazing videos, been telling my buds.. Do you accept questions about amp problems? Thanks a lot for what your doin

[@theguitarczar]

If it is possible to do, would it change the sound drastically if you lowered the voltage a little so you could use different output tubes?

[@leewarren]

Nice fix Brad! In Russia, the knobs go to 13 (according to the front panel)! Regarding the transformers, maybe 'folded' sheet metal was a more cost effective solution, than 'stamped' bell covers. As a sidebar, in 1975, I worked for the Canadian distributor of Hiwatt, where CSA required us to rivet metal shrouds onto the Partridge transformers to suit their regulations!

[@dryocum]

I really like what you did on this repair! You are really inspiring me to try and build my first amp. I’m a Network Tech building servers, fixing PCs and configuring routers and such. Never really did any electronic stuff. But Mojotone has a few amp kits I’m looking at for my first build. Do you think someone with my background can pull off building a guitar amp from a kit as a first build. I’m looking at the MOJOTONE STUDIO ONE 1 WATT 2-CHANNEL AMPLIFIER KIT. I need a practice amp with low watts so, I thought this amp would be a great kit to start with. What do you think? I would really appreciate your advice...

[@axeman2638]

In Australia the main voltage is nominally 240v but it's often higher than that. Amps with transformers that only handle 220v run hot and break down more often. Combined with the hot weather here the extra heat from running 250v through amps made to handle 220v is often fatal.

[@jenniferwhitewolf3784]

I always establish negative bias supply first.. without it, obviously the power tubes will turn on hard and red plate... Been building hi fidelity tube gear since before you were born, so this is voice of experience. I must say though that you have learned the craft of musical instrument amps damn well and find your vids refreshingly competent, with a nice bit of music tossed in for great fun.

[@ITheFight]

super informative video - and great playing man!

[@GrooveDuude]

Great info sir. Thanks. P.s. I am going to fabricate and Tolex a missing faceplate on a Mig 60. Same size enclosure? My client is upstate so I can't get my hands on it. Would you be so kind as to help me with factory dimensions. I believe it screws secure from the inside. Any help is appreciated.

[@fongy200]

I think it's Mica that Sovtek used in their transformers for it's insulating properties. That would be my guess as to what those panels are on the power transformer. See watching them from 5 years ago, every upload watched i have gained some knowledge that i have been able to take away with me. Thanks Brad.

[@darrelbigdaddywhite]

Very good video. Question concerning tubes and red plating: If your tube is red plating does it always mean there is a fault or could it be just a bad tube? What would it cost to ship a amplifier head to you from Oklahoma? thanks in advance?

[@TheGuitologist]

Yes, it could be a tube. If it was just one tube, I would have suspected a tube first, but this was both, so I knew it was in the bias circuit. Cost to ship a head...probably around $35-$40. Right now I'm taking a hiatus from outside repairs though. Hit me up around July, I should start taking things in again around that time: bradlinzy at gmail

[@redfishbum]

Great video Brad, as usual. However, I hope you checked the fuse. I had an old amp that i bought a while back, recently checked it because you say it so much and low and behold, not the right amp value...LOL. Thanks man! Bart

[@douro20]

I've taken apart a couple of HP tube instruments which had coaxial electrolytics with safety sleeves over them for the same reason.

[@davidmorales1136]

Love your videos! 26 minutes in.. is that Maiden in the background??

[@Wardell43]

I bought a Mig 60 new and and Mig 50 at a pawn shop back in the 1990's. They didn't do much for me, but I've learned a lot about tube amps since then. They were a good cheap basic no frills amp. They were in serious need of upgrades as this video points out.

[@frontbum420]

Whats your background as a guitar player?Something about those three note fast runs that I can't place the origin

[@FuzzMasterGeneral]

Brad do you know about the electro harmonix mig 50 clone . Does it fix all the bugs that happen on the og mig. For 600 bucks a 50 watt tube amp seems nice.

[@yarmouk334]

I’ve been trying to find a demo of this into a new Marshall MX412 240watt. I might just get the new Electro-Harmonix MIG50 “reissue”... Thoughts? I’m new to amp and I don’t know much. I don’t want a straight dirty amp rig since I sometimes play some ambient post-rock stuff and some looping with fuzz. A lot of 70s style spacey prog-rock stuff. I’m playing through an old Peavey 212 Classic that needs some new pots.

[@grizzwald5093]

We used to have a Sovtek mig100, it was a beast and never had any issues even after years of gigging still running strong! P.S. Love the dumpster vids!

[@lynndenham5221]

The material on that transformer for caps is either micarta or glastic common electrical insulator from back in the day

[@witeshade]

A friend of mine used one of these amps in his stoner rock/post hardcore band and it really nailed that tone extremely well.

[@simons.2281]

a nice collection of funky vintage guitars you have there.

[@jonathanidol8277]

I've been gigging with one of these for years. It's an absolute beast!

[@michaelinglis8516]

When you first changed schematics I saw v1 said 12ax7 but your first schematic said 12ay7. You caught it elsewhere though, those are interchangeable though right( not identical though)? The 12ay7 being less gainy/ less output?

[@MidnightVisions]

@5:00, that fiberglass material is called Micarta, it is an aviation grade insulator.

[@glasstronic]

Very cool! What is the type diode you you installed? Just curious; looks like old stock? Russian made?

[@TheGuitologist]

It's a silicon diode. It was an NOS one I got in some large parts haul a while back. Not sure on the model number. I just checked the voltage rating and knew it would work.

[@jonnybeck6723]

You really balanced and blueprinted (and then some) that Sovtek... Into another clean streetrod ala the Guitologist

[@henryhunter5026]

Those boards on the ends of the transformers were made of a type of bakelite. Iworked in the transformer business in the U.K, around 35 years ago and we used it a lot.

[@ScottFrein]

I had one of these many years ago, The channel one volume actually impacts channel two as well, if you crank both up it screams.

[@hammies.]

AHHHHHHH!!!!

[@smw397]

Where did you find that second schematic with all the part numbers included? I've been looking for that forever and all I can ever find is more links to the same original one by Bruce Collins.

[@FirstNameLastName-mo9li]

I have one of these bad boys. Replaced all the pots and all of the internal wiring. PCB looks and feels a bit cheap, but seems to be holding up pretty well. I am a little worried about the xformers, though. I run it through the stock 4 x 10 speakers of my early Fender Blues DeVille. It sounds like a piano! Turn it up and it produces beautiful, natural overdrive. I love this amp.

[@calescapee9642]

Those boards on the XFMRs are made of Micarta. I used to have a Skateboard made of this.

[@jayadams3244]

I have one of the new mig 50s and one of the power tubes like popped and vented out the top or something. Is that probably just a tube defect or indication of something else. The amp can only be like 2 years old so I can imagine any serious problems yet i hope.

[@SaultiBalldeip]

You did some real good probing there, real good!

[@TheGuitologist]

That's what she said. :P

[@MegaKnyte]

Just a guess on the transformer .. possibly they didn't completely enclose the transformer in metal like the old SUNN 1000S and 1200S amps with the Dynaco transformers .. and it was cheaper to put those bolted on covers as Gaussian covers

[@FIN_Der-Otter]

came here by accident, totally subbed.. awesome video! felt like watching a treasure hunt

[@Edyth_Hedd]

Guitologist, do the Sovtek tubes use the same numbering system as American tubes would use?

[@tokairic3925]

I read somewhere that metal plates around the transformers act like a shield to reduce hum.

[@MHSDankusPotatus]

I love your tiesco collection. that e110 looks to be in great shape

[@KC9MDO]

I have 92 Marshall with stock sovtek Tubes (valves) why is that? Just asking thanks.

[@Slicklickz]

I was a dealer for New Sensor from 1989-1991,aka Electro Harmonix.Mike Matthews told me it was pronounced with a hard "O" like in Soviet.,and being the owner of the factory,I'll take his word over anyone else's.

[@satchmodog2]

Great, now I need one of these amps

[@frantisca]

Do I pronounce Bradisky or Bradov ?... ;-) Well done mate ! And smooth playin' \m/

[@shimonbenloulou1778]

wow thats amazing tone! is that the amp or your magic?

[@gumbomudderx7503]

Old video so I don’t know if you’ll ever see this comment...but anyway, The input power voltage that is switchable from 110 American to 220 European, can a switch like that be installed on most amps? The reason I ask is I have two Redbear MK60’s that are 220V for the European market. I purchased a step up/step down transformer off of eBay to bump the 110volts from my wall outlet to 220volts to power them, but I can only do one at a time plus it’s a pretty clumsy set up and a pain to move around that way. It’d be nice to just be able to switch them to 110V and plug them in.

[@thetenarms]

What is the value of the bias diode you replaced?

[@crunchybobjones]

Micarta is that fiber board in the transformers, My uncle worked for Westinghouse for 25 years, They used that in transformers for insulation and spacers.

[@ALtheDoctorWho]

Yes that was the first thing I notices The Trans construction. I have a 60 Mig Sounds very close to a 50 watt Marshall Plexi

[@aynrandy1]

I remember an old guitar player mag that talked about these before they were shipped and the article said it was being started by Mike Matthews, who started electro-harmonix.

[@m600blu]

that material on the transformers is called phenolic a very strong wood composite good for high voltage and high temps.