How to repair Bias Electro Harmonix MIG-50 Tube Guitar amplifier

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  • เผยแพร่เมื่อ 28 ม.ค. 2025

ความคิดเห็น • 148

  • @d-labelectronics
    @d-labelectronics  5 ปีที่แล้ว +18

    Thank you all for the Birthday wishes. Love you all and thanks for being part of the D-Lab Family!

    • @l_shaun_bunds_l
      @l_shaun_bunds_l 5 ปีที่แล้ว

      Shoot me your intake address and I’ll send you a five pound spool of that solder

  • @schroee
    @schroee ปีที่แล้ว +2

    In the manual of the new MKII version, it mentions improvements in many sections of the amp, including the power supply. Perhaps they went on and fixed the bad soldering job?
    Happy belated Birthday, Terry. Amazing and very interesting video!

  • @dougmorisoli6482
    @dougmorisoli6482 5 ปีที่แล้ว +9

    Happy bday! 🎂🎉. The EHX MiG-50 is a “assembles in usa” reissue of the Sovtek Mig-50 made in Russia. Mike Matthews moved EHX to Russia in the 80s and made tubes and amps under Sovtek name. He brought EHX back to us later. But I bet you remember those old green Russian tank big muffs 😄

  • @Patrick_theshuttercanvas
    @Patrick_theshuttercanvas 3 ปีที่แล้ว +5

    This video has saved me hours of research. I love my EHX MIG-50 and now I know exactly what to do when I need to swap out the tubes. Subscribed! Thanks man.

  • @ringostarr4520
    @ringostarr4520 5 ปีที่แล้ว +1

    So we talked about prostate solder joints and your Johnson still works. Gotta love electronics sense of humor from a real pro. Happy birthday Terry!!

  • @MrLNielsen
    @MrLNielsen 5 ปีที่แล้ว +1

    Hope you had a great Birthday Terry

  • @Curtislow2
    @Curtislow2 5 ปีที่แล้ว +1

    HAPPY BIRTHDAY, Terry! Wish Mine still worked.LOL

  • @metalcavy33
    @metalcavy33 5 ปีที่แล้ว +1

    Happy Birthday D Lab

  • @barbmelle3136
    @barbmelle3136 5 ปีที่แล้ว +2

    From Leo: I have heard multiple comments where players do not like the sound of the MG50 chassis. If they come with the output tubes at less than 1/2 bias current, making that adjustment should really make the tubes more responsive. Happy birthday!

  • @Nirky
    @Nirky 5 ปีที่แล้ว +2

    Happy Birthday, D-Lab!

  • @fmercer54
    @fmercer54 5 ปีที่แล้ว +1

    Yup happy birthday Terry 🎂🍷

  • @sski
    @sski 5 ปีที่แล้ว +1

    Happy Birthday Terry!!

  • @Finom1
    @Finom1 5 ปีที่แล้ว +4

    Happy Birthday Terry, Bless you and your family!!!

  • @mattdixon333
    @mattdixon333 5 ปีที่แล้ว +1

    Happy Birthday Terry!

  • @simonsmith2802
    @simonsmith2802 5 ปีที่แล้ว +1

    And Happy Birthday Terry I hope you have had a great day

  • @Bigjoedo66
    @Bigjoedo66 5 ปีที่แล้ว +2

    Well done Terry!! Happy Birthday!!

  • @bretthibbs6083
    @bretthibbs6083 5 ปีที่แล้ว +1

    happy birthday Terry

  • @andrewgillis8572
    @andrewgillis8572 5 ปีที่แล้ว +1

    great video - hope i didn't seem harsh on the vintage show comment, you gave us plenty of detail in this one!

  • @lincolnmicrophonellc
    @lincolnmicrophonellc 5 ปีที่แล้ว +1

    Very nice of you to share the service procedure! Happy late birthday!

  • @thedevilinthecircuit1414
    @thedevilinthecircuit1414 2 ปีที่แล้ว

    You got a nod for recording track 10 on that CD. Cool!

  • @Marceloriighiii
    @Marceloriighiii 5 ปีที่แล้ว +1

    Happy birthday Terry, Cheers !!!

  • @Darrell_Coquillette
    @Darrell_Coquillette 5 ปีที่แล้ว +1

    Happy Birthday D-Lab! You still look younger then the equipment you repair.

  • @daveogarf
    @daveogarf 5 ปีที่แล้ว +4

    HAPPY BIRTHDAY, Terry! And may you (and Marsha) have many more.

  • @sammyrothrock6981
    @sammyrothrock6981 5 ปีที่แล้ว +1

    Wow 535 volts to the plates is pretty 🔥.. I had an old sovtek 50 watt tube midget back in the 90s That thing is probably close to 60 watts RMS.. Ringed solder joints are the Big enemy of PCB boards and heat is another. I always look especially at those power tube sockets. Good video Happy Bday Terry

  • @lavejim11
    @lavejim11 5 ปีที่แล้ว +1

    Happy Birthday Terry...Keep the videos coming!!

  • @josephmartinez3851
    @josephmartinez3851 5 ปีที่แล้ว +2

    Thank for spending your birthday with us...

  • @vijaymerceline
    @vijaymerceline 5 ปีที่แล้ว +1

    Happy Birthday Terry! Hope you had a wonderful day.

  • @TheRadioShop
    @TheRadioShop 5 ปีที่แล้ว +7

    A very Happy Birthday Terry. Really enjoyed the amp repair. Man that Johnson shirt is awesome! I have to get me some made. Need to start the cosmetic restoration on my two Viking II's soon. But in the mean time got a Apache TX-1 on the bench with no audio. Have a great week end.

    • @gbowne1
      @gbowne1 5 ปีที่แล้ว +1

      Have fun with the Apache :) I want the shirt too :)

  • @schreds8882
    @schreds8882 5 ปีที่แล้ว +1

    Happy Birthday, Terry! 🎂

  • @mendamp1715
    @mendamp1715 5 ปีที่แล้ว +1

    Happy Birthday, Terry! Always look forward to your videos!

  • @Cavemannspace
    @Cavemannspace 5 ปีที่แล้ว +1

    Congratulations on another successful orbit!

  • @rciancia
    @rciancia 5 ปีที่แล้ว +1

    Happy Birthday my friend... I call today Doubler Wine Saturday. Terry, its very hard to be sure, but the right Filter cap looks like the top is slightly bulging. Very hard to be sure so mentioning it just in case. The bias adjustment was very thoughtful by the manufacturer to put there.. that's a good DLAB product enhancement to see make and sell... :P hint hint... Happy birthday bud...

  • @gatekeeper65
    @gatekeeper65 5 ปีที่แล้ว +1

    Happy birthday good sir. I hope you have many, many more. I'll have a drink to your health.
    Your friend Megan sounds awesome, much luck to her in her career.

  • @drdfx159
    @drdfx159 5 ปีที่แล้ว +1

    Happy Birthday Terry! Thanks for sharing your knowledge!

  • @henkkman
    @henkkman 5 ปีที่แล้ว +1

    Happy birthday Terry! Great channel!

  • @preiter20
    @preiter20 5 ปีที่แล้ว +2

    Happy Birthday Terry! Thank you for sharing your vast knowledge with us and wishing for many, many happy returns!

  • @jeffdowning4877
    @jeffdowning4877 3 ปีที่แล้ว

    I have a Mig 60 and its recommended bias on schematic is 80mv, which is ihe same parallel config as the Mig50, so 40mv per tube. . But I think it uses EL34s so.....but looks like you found the answer from them and yours is 62-65mv. So I'll shut up now. Haha. You're the best! Cheers Komrad! Salute!

  • @bigmac965
    @bigmac965 5 ปีที่แล้ว +1

    Happy Birthday, Terry! Many thanks for sharing your knowledge and love of electronics. I'm saluting you with some vintage grape juice in my D-Lab wine glass. (Alas, I'm out of wine..)

  • @1967250s
    @1967250s 5 ปีที่แล้ว +1

    Many Happy Returns, Terry. Fun to watch your vids.

  • @w4jmc
    @w4jmc 5 ปีที่แล้ว +1

    Happy Birthday

  • @schreds8882
    @schreds8882 5 ปีที่แล้ว +3

    Ha! The solder spindle I inherited from my dad is Kester but it doesn't say what type it is. I'm sure he bought it back in the 80's or possibly the late 70's. I think this spindle will last the rest of my life. Don't worry, Terry, I don't solder often; I know my limitations. 😛

  • @greasymonkeyguitars9292
    @greasymonkeyguitars9292 5 ปีที่แล้ว +1

    Happy Birthday, D-lab!

  • @willievivanco1
    @willievivanco1 5 ปีที่แล้ว +1

    happy birthday my friend

  • @elvis_chen
    @elvis_chen 5 ปีที่แล้ว +1

    HAPPY BIRTHDAY TERRY!
    I like to say I enjoyed watching your videos, not only the knowledge you shared but also your calm voice is reassuring.

  • @MikeY-hl5pi
    @MikeY-hl5pi 5 ปีที่แล้ว +1

    Happy Birthday! And nice video too!

  • @bmh67wa
    @bmh67wa 5 ปีที่แล้ว +1

    My Johnson (Messenger II black face CB) still works too.
    Happy getting older day!

  • @dhpbear2
    @dhpbear2 5 ปีที่แล้ว +1

    13:20 - Those test-points are a plus. Just make sure you don't short the probes to the chassis!
    Happy '39th' birthday :)

    • @johnb4024
      @johnb4024 ปีที่แล้ว

      Seems like a design flaw doesn't it?

  • @haroldsparkman6008
    @haroldsparkman6008 5 ปีที่แล้ว +5

    Happy birthday Terry. Another wine job. I mean fine job!

  • @jimtalltheislandbrothers6639
    @jimtalltheislandbrothers6639 5 ปีที่แล้ว +1

    Cheers to you Terry.

  • @strangequark420
    @strangequark420 5 ปีที่แล้ว +1

    Happy birthday!

  • @izzyauna8814
    @izzyauna8814 5 ปีที่แล้ว +1

    Happy B-day. Love the video

  • @jazzey69
    @jazzey69 5 ปีที่แล้ว +1

    Have a very happy Birthday terry...blessings from England UK...:-)

  • @mndean5652
    @mndean5652 5 ปีที่แล้ว +3

    "Tower, this is Ghost Rider requesting a flyby" - EH circus boards are a lot more entertaining than Fenders!

  • @blues61
    @blues61 5 ปีที่แล้ว +1

    Happy Birthday Mr. D-Lab! Wishing you a happy, healthy and prosperous year ahead. Glad to hear good news about your Johnson as well... :-)

  • @jimgiordano8218
    @jimgiordano8218 5 ปีที่แล้ว +1

    Happy Birthday Terry, and thank you for another great video.

  • @Jah_Rastafari_ORIG
    @Jah_Rastafari_ORIG 5 ปีที่แล้ว +1

    Happy birthday there, Dexter!
    (If you'll allow me some constructive criticism, the company in question pronounces their name, 'har-MON-nix')

  •  5 ปีที่แล้ว +1

    "FELIZ CUMPLEAÑOS TERRY"

  • @johnsimms3957
    @johnsimms3957 5 ปีที่แล้ว +1

    Great job Terry.

  • @jeffreypetchharrison4363
    @jeffreypetchharrison4363 5 ปีที่แล้ว +1

    happy birthday to you you old phart .. tnx from another old phart ..jeff

  • @rockettcrawford890
    @rockettcrawford890 5 ปีที่แล้ว +1

    Another great video. Happy birthday! Love it when you're working on tube amps.

  • @johnnaighley9252
    @johnnaighley9252 5 ปีที่แล้ว +1

    Happy belated birtday, Terry. You've inspired me so much with your numerous guitar amp projects. Thanks for that. I've accomplished to build some of them.

  • @roberthurless4615
    @roberthurless4615 5 ปีที่แล้ว +1

    Happy birthday Terry, and I am glad to hear that your Johnson still works. Ha-ha-ha

  • @theRodofwar
    @theRodofwar 5 ปีที่แล้ว +1

    WoW !!!! Happy B-day T-MAN !!!!!! Great Video !!!!!!!!!!!!

  • @Satchmoeddie
    @Satchmoeddie 5 ปีที่แล้ว +1

    When they build those pin 8 is the pin they used to adjust where the socket is set for height, and alignment so it's slid around until the socket is where it's supposed to be, and then pins 1-7 are soldered in, but all the flux was cooked off the pin 8s during the initial positioning of the sockets. They SHOULD suck that fluxed up crap solder off pin 8 and resolder it. NONE of those solder joints look acceptable let alone good. The ONLY time I add extra liquid flux is for chassis grounds, and a few select places where I'll use paste to avoid overheating, or for SMD stuff. There is a local boy made good who made amps for Deathlock and other Adult Swim shows, and his first amps were modified Sovteks. Very nicely modified Sovteks!

    • @Satchmoeddie
      @Satchmoeddie 5 ปีที่แล้ว +1

      And why do you need to look up the bias current? Set those tubes up for 60-80% plate dissipation for Watts, and see where the customer likes the sound. Below 60% it gets muddy, above 80% you eat tubes faster. Ohm's Law! NOS Sylvania 6L6GC STR 415s can be biased at 90% or more, but this new Sino/Russian/Slovakian made stuff? NO WAY. 73s KI7AQJ

  • @jamiemascola6614
    @jamiemascola6614 2 ปีที่แล้ว

    Happy belated, Terry! Looks like a bad wave-solder job. Either they didn't get their flux spray right, or ran the conveyor too fast. The tube sockets would have been masked off for wave with Kaptan tape, and done with selective solder or manually soldered after all of the top layer components went down.

  • @cclol8786
    @cclol8786 5 ปีที่แล้ว +1

    Happy birthday Terry, and thanks for the video : another great one and some more to learn for us... I thought birthday gifts were the other way around! 😃

  • @carstenvalentina
    @carstenvalentina 5 ปีที่แล้ว +1

    Happy Birthday!

  • @freddycookjr.2164
    @freddycookjr.2164 5 ปีที่แล้ว +1

    HAPPY BIRTHDAY THX FOR YOUR SERVICE SO MUCH CONFUSING AMP TECH ON WEB YOU ARE STRAIGHT TO THE POINT LOVE IT

  • @langhilau
    @langhilau 5 ปีที่แล้ว +1

    Happy Happy birthday Terry, just like vino you and your videos get better with age. I hope you have many more also tell Marsha to be extra nice to you, LoL

  • @fatman8x57
    @fatman8x57 5 ปีที่แล้ว +1

    I'm betting the schematic you found was for the older ones that were made and distributed by sovtek. The new EHX ones have a completely different layout and I bet they added the bias section.

  • @DeadKoby
    @DeadKoby 5 ปีที่แล้ว +5

    The Sovtek Mig-50 was made in the 90's with Russian style parts. the EH version would be considered a re-issue, and uses "general" electronic parts. If you see the original, the resistors and pots are especially unusual, and may have been soviet surplus.

  • @patrickkoenigsfeld1253
    @patrickkoenigsfeld1253 3 ปีที่แล้ว

    You sir, are a treasure trove of information. Subscribed. Can't wait to watch everything you do.

  • @HBSuccess
    @HBSuccess 5 ปีที่แล้ว +1

    Happy Birthday T-man! Hope you found a nice ‘07 Duckhorn Cab or similar to celebrate 🎉 🥳

  • @kaleoride
    @kaleoride 4 ปีที่แล้ว +2

    Great amp, I have two of those, very clean, the best pedal platform

    • @algorithm007ify
      @algorithm007ify 2 ปีที่แล้ว

      Agreed..especially for the price.

  • @chitafast5976
    @chitafast5976 3 ปีที่แล้ว +1

    Love your videos, actually I fixed a few amps because of your knowledge!!! I just want to say thanks and keep them coming

  • @ferraridinoman
    @ferraridinoman 5 ปีที่แล้ว +1

    Happy Birthday Young Terry! (Must be pushing 30 this year!!) ha ha!

  • @GonzGunner
    @GonzGunner 3 ปีที่แล้ว

    I really love watching your videos and I have learned a lot, beyond just being satisfied that I could change tubes and bias an amp. You point out what's wrong, why it is causing the problem, and how to repair it and what parts to buy and where to get them. And you are a Godzilla fan to boot! I love Godzilla! But to be honest, I think the best Godzilla movie was the first one, it encompassed all aspects of the human condition against the backdrop of the emerging Cold War, not to mention it was scary as hell! My favorite, ( and yes, I think the most scary scene ) was when Dr. Yamane, with his daughter and his team, with Steve Martin (Raymond Burr) in tow, were on Odo Island, walking up the hill, and Godzilla appears, and as they all start to run, he lets out that vicious, bone chilling roar!

  • @kirkmurphy2165
    @kirkmurphy2165 5 ปีที่แล้ว +1

    Terry, hello and Happy Birthday belated. I thought that bias feature was really neat and thoughtful how the company
    put that on the back. I was intrigued they bias both tubes through a single circuit rather than biasing each tube separately.
    I do understand cost is involved though. So unless you do some probing and calculations a person won't know if each tube
    is truly biased equally. I mean, sometimes tubes aren't matched. Is this a correct assumption? Anyway, it is still a nice feature.
    I enjoy your videos and am learning through them and others.Reading books as well to possibly have a small repair shop to
    supplement my retirement income when that happens, shortly.
    Thanks, Kirk Murphy

  • @rubyrosemicrophone5018
    @rubyrosemicrophone5018 5 ปีที่แล้ว +1

    Happy b-day!

  • @rayinpau.s.a.6351
    @rayinpau.s.a.6351 5 ปีที่แล้ว +1

    Hi Terry , I wanted to ask you , I have a Marantz receiver and it has a hissing sound in the left side that is intermittent . do you repair things for viewers ? Please Sir , I trust in you , and would really like to have it working . I just found your site and have watched you do walk arounds with your Wife . you seem to know a lot about stereos . I appreciate your time . let me know how we can go about taking care of the Marantz . Thank You Terry and Happy Birthday ! . Ray in Pa

  • @SuperBuzzbomb
    @SuperBuzzbomb 5 ปีที่แล้ว +2

    I see a Sencore SG-165 in the background. Have you used it on any of your repairs/ restorations? How about a video of it in use? Happy Birthday!

  • @8xlaxx
    @8xlaxx 5 ปีที่แล้ว +1

    Happy BDay Terry! Enjoy some 14Hands tonight. Keep the Johnson happy! HA

  • @jakeblues3676
    @jakeblues3676 5 ปีที่แล้ว +2

    Happy Birthday Terry, love Da Johnson’s too!!
    Question: because of all the cold and non-existent solider joints and with those being double sided boards why did you not unplug the wires and pull the boards to check both sides?? While I know it’s a huge pain it would be a much better observation and chance to confirm every joint is properly soldiered eliminating bad joints.

  • @terencekaye9948
    @terencekaye9948 5 ปีที่แล้ว +1

    Happy Birthday Ter.. :)
    Can I get a hard copy of the Tecn info for biasing.. I'll try and email you,,, Thank you..

  • @Alex-ze9tv
    @Alex-ze9tv 4 ปีที่แล้ว +1

    With 5881 mine it only goes up to 55. Can I piggy back a resistor on the existing resistor?

  • @douro20
    @douro20 5 ปีที่แล้ว +1

    I say the power supply caps probably won't give you much trouble but I would still replace the rest of the electrolytics with better quality ones.

  • @Electrondivize
    @Electrondivize 5 ปีที่แล้ว +2

    Why is it you set up the bios so well for each tube,, and not check the DC offset

  • @s68139c
    @s68139c 2 ปีที่แล้ว

    Very informative! You rule! Appreciate this so much!

  • @clint4004
    @clint4004 5 ปีที่แล้ว +1

    Ever think of making a Marshall type amp out of a Dynaco Mark III Transformers and such??

  • @kendavis8046
    @kendavis8046 5 ปีที่แล้ว +2

    Well, happy birthday! You are almost a Libra, my own sign. (But to be completely honest, I give no credence to how the stars were aligned when I was born, because that would be just silly.)

  • @clivedavies3
    @clivedavies3 5 ปีที่แล้ว +1

    Really enjoyed your video love ham radios everything I own is valve including guitar amps keep up the good work. Happy birthday by the way.

  • @TheNewNoise7
    @TheNewNoise7 ปีที่แล้ว +1

    Anyone know the functions of v1 v2 and v3 preamp tubes? Curious if different tubes will yield different sounds…

  • @MrArfisher
    @MrArfisher 5 ปีที่แล้ว +1

    Happy birthday, man. I wonder what year you're at and...how that amp sounds?

  • @bobbymacisontv
    @bobbymacisontv 9 หลายเดือนก่อน

    Love this amp I just got one new. The only wish I have is a lower noise floor. Any ideas how to tackle that?

  • @RobertKohut
    @RobertKohut 5 ปีที่แล้ว +1

    Good job old man.... :-) (that's a Happy Birthday) :-)

  • @luzsounds
    @luzsounds 2 ปีที่แล้ว

    Great video. How can I find the spec sheet to bias a Sovtek MIG 50H? I'm asummnig the 50 and 50h have different schematics.

  • @galloway7448
    @galloway7448 5 ปีที่แล้ว +1

    Great channel. Great people!! Thank you for your knowledge and entertainment 😎🤘🏻🎸

  • @drivedentfreecom
    @drivedentfreecom 3 ปีที่แล้ว +1

    Do you happen to know the value of resistor 35?
    Thanks.

  • @sgtrutters5892
    @sgtrutters5892 5 ปีที่แล้ว +1

    Happy birthday! I do have a question on your Ungar iron, I'm looking for a decent iron for chassis work, can you tell us the model of the tip and handle?

  • @jamesschroeder3313
    @jamesschroeder3313 5 ปีที่แล้ว +6

    Well we now know how to get a broke Johnson up and working without D-Lab.
    Try to insert a little blue pill in the input jack.
    Finally if you can't turn off your Johnson after four hours pull the plug.