BGW750C Stereo Power Amplifier No Sound Repair

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  • čas přidán 27. 08. 2024
  • This one has monster power when it works.
    Sound quality? There are much better sounding amps, but for pure ground shaking power, this one has it!

Komentáře • 192

  • @tyronenelson9124
    @tyronenelson9124 Před 3 lety +7

    Its good that you give the warnings of dangerous high voltages for the safety of other people with little to no knowledge of electrical equipment.

    • @rogertyler3237
      @rogertyler3237 Před 3 lety

      Me I Don't Mess With That Old
      Obsolete Stuff. I EOL It

    • @tyronenelson9124
      @tyronenelson9124 Před 3 lety

      @@rogertyler3237 You might not but a lot of people still do.

  • @smason
    @smason Před 3 lety +14

    In the very few repairs I've tackled, I've found a good solder re-flow will work wonders on older equipment. Excellent vid!

    • @12voltvids
      @12voltvids  Před 3 lety +6

      Yes likely a bad connection. More than likely the plug.

    • @joshm264
      @joshm264 Před 3 lety +3

      Yep, i got a Sega Genesis for $5 and fixed it by reflowing

  • @davenally8672
    @davenally8672 Před 3 lety +10

    I used to work on these death traps. Once I had a TO95 transistor blow into my forehead which left an impression for weeks, much to the amusement of my fellow technicians. As I'm sure you know, always be extra careful when working on such beasts as they don't give second chances. Loved and subbed the channel BTW!

    • @12voltvids
      @12voltvids  Před 3 lety +6

      I was once thrown across the shop my a microwave power supply. Everyone laughed.

    • @MetalGreggNY75
      @MetalGreggNY75 Před 3 lety +1

      Hearing & experiencing things like that is always fun, right!?!?…NOT!!

  • @jeremytravis360
    @jeremytravis360 Před 3 lety +8

    I worked in a big London West End Cinema when Earthquake was first shown.
    The film company sent a couple of engineers to install the Speaker and Amplifier.
    The sound was phenomenal. I often wondered if it would dislodge the old plaster ceilings when the films were shown.

  • @j.t.cooper2963
    @j.t.cooper2963 Před rokem +1

    I was 10 years old in 1974. I remember going to see Earthquake in "Sensurround" at the theaters and the seats did indeed shake. Little did I know that these were the amps used.

  • @andred1951
    @andred1951 Před 2 lety +2

    I worked for Automated Processes inc (API) in the 1970's. We made recording consoles for studios. We also made some amps for Sensoround used for Earthquake.

  • @markanderson350
    @markanderson350 Před 3 lety +3

    I watched earthquake way back, the sound was amazing. The whole theater shook.i was told it's a separate audio track triggered off the movie sound. I loved it and sad it will never come back.

  • @reacey
    @reacey Před 3 lety +5

    Watching this in England at 3 in the morning, love your videos.

    • @RWL2012
      @RWL2012 Před 3 lety +1

      I'm watching this in Wales at 3 in the afternoon :)

  • @J.Christ-man
    @J.Christ-man Před 3 lety +3

    I have a bgw 500d, I call it the "arch welder" 😂 I made a buddies house power dim with every bass punch during a New year's party. The only repairs I've made were changing out the big resistors as they do get very hot and I've had one burn up, not now with 10watt flame proof one's 👍. Get amp for sub channels with the high distortion as it's not as noticable.
    I also just remembered I had a similar issue with the plug connector having slight oxidation from living in the West coast of BC. Terminal fretting. Cleaned terminals and installed dielectric grease, all good now.
    Good job 👌 keeping the brute going 😁

  • @djfrank59
    @djfrank59 Před 3 lety +3

    The best solid state amplifier ever made. I used to be an authorized warranty station for them back in the late 80's early 90's.

    • @12voltvids
      @12voltvids  Před 3 lety +1

      Oh yes they were good. I would take one any day.

    • @jdmccorful
      @jdmccorful Před 3 lety

      Hey Frank, did you go to Chi?

    • @djfrank59
      @djfrank59 Před 3 lety

      @@jdmccorful No

    • @djfrank59
      @djfrank59 Před 3 lety +1

      @@12voltvids I have 2 750B's which have the LED level display. Currently using them in my stereo system with an Ashley 2 way active crossover.

    • @davenally8672
      @davenally8672 Před 3 lety +1

      Great amps agreed, but up your life insurance if you're working on them regularly

  • @neverknowit11
    @neverknowit11 Před 3 lety +6

    Brian Gary Walkner graduated from Alexander Hamilton High in maybe 1966-1968. My friend Jon Prudeaux who created his own company Crest Audio was one of the Engineers then. BGW was in Culver City California. They were the first company to use a Crow-Bar circuit to protect the Output Transistors. 100% Hand built and soldered Amplifiers.

    • @ny9h
      @ny9h Před 3 lety +1

      bgw TRIED TO GET USERS TO REALIZE THAT Crown DC-300 would max out & clip into efficient JBL speakers and burmn out the voice coil .... the trick was to run the amps at SOA safe operating area and NOT to clip them ..effectivlly causing 'DC' across the voice coil.. I sold many of BGWs amps in Illinois & Wisconson back in the 80s . Also the DC300 would blow a final and send the rails to the voice coil ...PUFF causing an out of warranty on the speakers ( JBL ) Our firm represented both JBL & BGW....back when JBL used indepentent sales rep companies...." good ole days"

    • @ny9h
      @ny9h Před 3 lety +1

      as far as distortion... I would suggestr you measure ...could be a WAY TOO CONSERVATIVE rating,

    • @FOH3663
      @FOH3663 Před 3 lety

      Nice to know!
      Thanks for that. Crest certainly took things to another level ...ie., robust, BIG power, high damping factor.
      Peavey bought Crest if I'm not mistaken.

    • @lunam7249
      @lunam7249 Před rokem

      ❤❤❤👏👏👏🔥🥇🌝

  • @1959Berre
    @1959Berre Před 3 lety +3

    "Earthquake"... Those were the days. I saw the movie in the theater when I was 15 years old. It was a thrill (pun intented). The story was second to none, it was all about the sensurround effect. I remember the great Charlton Heston, aka the mythical 'Ben Hur, playing the role of Stewart Graff, a construction worker in "Earthquake".

    • @guitareveryone
      @guitareveryone Před 3 lety

      I purchased a Universal 8 condensed 20 minute super 8 sound version of that film way back in the early 80’s from a company called Famous Films in Florida. I used to hook my projector speaker out to a cheap solid state guitar amp and crank it to get the rumble effect. And of course I’ve seen the movie in it entirety. Cool movie.

  • @christhompson6010
    @christhompson6010 Před 2 lety

    Wow i finally found someone who speaks english who deals with home theater and commercial amps and not car amps. will subscribe

  • @Godzilla941
    @Godzilla941 Před 3 lety +5

    Good way to effortlessly fry tweeter voice coils (whoops...) It's also easy to short component leads to the heatsink. I pre-cut all the leads through a perfboard when working on these to keep that from happening. It should be able to do 800W into 8 ohms in bridge configuration just before clipping...good for quickly heating a room and overheating the standard 16AWG AC line cord! Time to hook it up again since winter is almost here.
    I still can't get over the absolutely mental size of the power transformer and filter caps in these things...back when the purchase price got you a healthy portion of gravitational pull.

  • @michaelturner4457
    @michaelturner4457 Před 3 lety +2

    Watching this at 12:30pm here in Thailand. Nice amp.

  • @teresitamontebon5342
    @teresitamontebon5342 Před 3 lety +1

    Thank you Dave you give a warning for the high voltage amplifier.

  • @iceman45ification1
    @iceman45ification1 Před 3 lety +2

    That's a lot of T-03's in there. Bet that amp sounded amazing in it's day. 😍👌

    • @12voltvids
      @12voltvids  Před 3 lety +1

      Not the cleanest of amps but at 130db who cares.

    • @danmackintosh6325
      @danmackintosh6325 Před 3 lety

      Not sure how I missed this vid but found it now. These amps are awesome for how simple they are, there's a few similar (but obv. silicon) builds floating around YT where they simply point-point the whole thing together with no PCB or cabinet & I keep meaning to make one one day! At 130dB who's worried about THD numbers anyway, chances are what you're listening to wasn't produced enough to matter. Almost enough to drown out the wails of audiophools :D

  • @paul.l.haywood2421
    @paul.l.haywood2421 Před 3 lety +1

    ""Sensurround"" was this amplifier driving a Cerwin-Vega 18 inch subwoofer model 189 ES they were in a horn loaded cabinet, the type of horn depended on the theater they
    were installed in. The number of amps and subs depended on size of theater.

  • @elfd18s
    @elfd18s Před 3 lety

    Great Amplifer! The 750G had the best meters! The GTA & GTB were amazing sounding amplifiers.

  • @stefanmarinescu5086
    @stefanmarinescu5086 Před 3 lety +2

    Great video + bonus history... Thank you.

  • @rubenp8750
    @rubenp8750 Před 3 lety

    The 750 G was the last of those big amps. It had a large led display for output power and thermal light for power supply and heat sink and dc offset lights as well.

  • @bigsscore8378
    @bigsscore8378 Před 3 lety +2

    I enjoy your videos so much thank you very much keep up the good work.

  • @brotherspock8180
    @brotherspock8180 Před 2 lety +1

    I managed to collect three of the 500d models over the years. I think they are nicer looking than the 750s, having the brushed aluminum face plates. Supposedly they have less power than the 750s but the schematics for them as far as I could remember were essentially the same. I never knew why they were rated having a little less power.

  • @pauldionne2884
    @pauldionne2884 Před 3 lety

    Great job. Though it might also be a good idea to also touchup the solders on the socket for the wiring harness. Might have missed you giving it a good look over and determining it was OK.
    Nice to see the boards didn't show signs of overheating - must be well engineered.

  • @rogertyler3237
    @rogertyler3237 Před 3 lety

    Just Like Those Old Tube Radio's & Tv's

  • @wendellporter4875
    @wendellporter4875 Před 3 lety +3

    i came across a 1970's cerwin vega amp it was being tossed i grabbed it i restored it and most of the output transistors where shorted, came out of a club if i recall

  • @3dsmaxrocks699
    @3dsmaxrocks699 Před 3 lety +1

    Nice job. Amazing skills you have!

  • @user-tc5nk6oq7u
    @user-tc5nk6oq7u Před 3 lety +2

    Hi mr good vare good
    Thes videoi. Thank you for thes video.
    Abdul. Iraq bagdhad

  • @hestheMaster
    @hestheMaster Před 3 lety

    So just re-seating the plug is the only thing you changed. That allowed the relay protection to kick in. So it works again. Nice !😉

  • @MetalGreggNY75
    @MetalGreggNY75 Před 3 lety

    Can you imagine going to a movie theater w/out having surround sound!?!? I remember those days….it’s wild to think that.

    • @12voltvids
      @12voltvids  Před 3 lety +1

      I haven't been to a movie theater in forever. Last one I saw was die another Day and before that lethal weapon 4 and that was 22 years ago.

    • @MetalGreggNY75
      @MetalGreggNY75 Před 3 lety

      @@12voltvids Last one I was at was Avengers End Game….I think.

    • @MetalGreggNY75
      @MetalGreggNY75 Před 3 lety

      Dave, Die Another Day is a pretty good James Bond Film….but Connery & Moore are my favorite Bonds.

  • @Antagon666
    @Antagon666 Před 3 lety

    That amplifier looks so cool ! Vintage electronics is the best, since the qaulity was on whole another level compared to " consumamble electronics" nowadays. Things were built to last nuclear war back then.

    • @12voltvids
      @12voltvids  Před 3 lety

      And very simple design compared to today's stuff.

  • @johnhodgson5313
    @johnhodgson5313 Před 2 lety +1

    Midway was another movie that used Sound surround.

  • @Mr39036ce
    @Mr39036ce Před 3 lety

    Most 50''s theater setups for sound were 4 channel magnetic. The channels were left center right and effects.

  • @1959Berre
    @1959Berre Před 3 lety +1

    I noticed a couple of suspicious 'rings' in the solder connections of the upper row of power transistors (22:35). Probably bad connection due to heat stress. That solder may have been reconnected when you unsoldered/soldered the emittor resistors prior to testing the transistors. Better reflow them all.

  • @tottimejdi5820
    @tottimejdi5820 Před 2 lety

    very nicely diesgned amp

  • @MrChrisRP
    @MrChrisRP Před 3 lety

    6 minutes in before work even, mind blown.

  • @er5406
    @er5406 Před 3 lety

    Lm318 opamps are still available, maybe obsolete but still available. We used to use many LM308 in geophysical electronics.

  • @Mr39036ce
    @Mr39036ce Před 3 lety

    Just FYI the LM 318h op amp is all over ebay for about $5-10. They like to take out a positive and a negative output when a channel goes. Will trip relay out if one gets leaky too.

  • @rohiteugenemurray7879
    @rohiteugenemurray7879 Před 3 lety

    You are simply the best. Love your videos!!!! :)

  • @lunam7249
    @lunam7249 Před rokem

    this has awesome sound quality, and terrifieing power

    • @12voltvids
      @12voltvids  Před rokem +1

      You think this thing has power you should see my crest vs900. Now that's power. 450 watts per channel!

    • @lunam7249
      @lunam7249 Před rokem

      @@12voltvids 1985 vs 2019 tech.....hhhmmmmm.....

    • @12voltvids
      @12voltvids  Před rokem +1

      @@lunam7249 crest vs900 is 1997 vintage.

    • @lunam7249
      @lunam7249 Před rokem

      @@12voltvids 1985 vs 1997 tech.... the guy that started crest, worked as a tech for BGW in the begining...lots of power you have.... sound similar to carver PM900 pro.....that has woofer killing powers!! i think is 450 into 8 ohms x 2 channel like yours...i owned a bunch of crest amps back in the day

    • @12voltvids
      @12voltvids  Před rokem +1

      @@lunam7249 260x2 into 8, 450 x 2 into 4. 1100 into 2 bridges mono.
      You are right the guy that started crest was an engineer with bgw on 70s. Crest was merged into Peavey. Yes it sounds simply amazing and will drive any speakers you can throw at it. It is pretty much unclipable as it has an electronic attenuator that will compress the input for peaks that would normally clip protecting speakers at that extreme power. I have killed a few speaker fuses by accident.

  • @38911bytefree
    @38911bytefree Před 3 lety

    Nice heavy duty contruction .. no expense

  • @Oldgamingfart
    @Oldgamingfart Před 3 lety +1

    Might be a good idea to advise the customer against hot-swapping cables or connectors on an absolute brute of an amplifier like this! It's asking for trouble! ⚡

  • @Thanson199415
    @Thanson199415 Před 3 lety +1

    Shame somebody takes your content, slows it down, and says it's theirs. :P ruthless people

    • @12voltvids
      @12voltvids  Před 3 lety +2

      Didn't take my content. Took musicbakery royalty Free music and slowed it down and claimed it was theirs. I used that track on a road trip video and got a claim. I disputed it as usual as I have a license to use it.

  • @2bad83
    @2bad83 Před 3 lety +5

    It’s called the magic touch 🤔

  • @tazmaniachill
    @tazmaniachill Před 3 lety +11

    3.10 am uk time, COVID victim no sleep I remember seeing earthquake

    • @OGmolton1
      @OGmolton1 Před 3 lety

      doing better I hope? that sounds pretty amazing, i can't believe they did all that for a movie

    • @Synthematix
      @Synthematix Před 3 lety

      uk here too ray 3am lol

  • @samuelsalins8309
    @samuelsalins8309 Před 3 lety +1

    Great video tnx. 👍.

  • @tyronenelson9124
    @tyronenelson9124 Před 3 lety +2

    So how exactly does 230 watts per channel end up being 750 watts bridged?

    • @solitaire5142
      @solitaire5142 Před 3 lety +1

      360 wpc @ 4 ohms = 720w @ 8 mono bridged. In reality they did closer to 800w

    • @lunam7249
      @lunam7249 Před rokem

      @@solitaire5142 they do more...this is underated......they are massive 8 ohm amplfiers

  • @Ratchet_effect
    @Ratchet_effect Před 3 lety

    You can still buy the LM318 in that TO-5 metal can style.
    Future reference' 1 Balance Compensation-1 2/3 Inputs 4 -V 5 Balance Compensation-3 6 Output 7 +V 8 Compensation-2

    • @12voltvids
      @12voltvids  Před 3 lety

      If you look at the board it has the layout for dip package.

    • @Ratchet_effect
      @Ratchet_effect Před 3 lety

      I don't think everyone will think of that, even if they could clearly see in the video, they'd still have issues? as the pin-out is in a circular orientation. Also if they had a burnt board etc.. having the text with the pin-out would help would it not?

    • @matambale
      @matambale Před 3 lety +1

      You can also bend the pins of an LM318 TO-5 package to fit its DIP layout.
      -- See docplayer.net/docs-images/41/2273859/images/page_15.jpg

  • @Ted_E_Bear
    @Ted_E_Bear Před 3 lety

    Need them all like this!

  • @SylvainBOSSON-og8fi
    @SylvainBOSSON-og8fi Před 3 lety

    it seems a real good ampliflfier good built

  • @zx8401ztv
    @zx8401ztv Před 3 lety

    A big old beast, a brute as you said :-D
    Oddly i thought there was a semi short through a mica insulator so the heatsink had power, the heatsink is earthed to the case so it could have leaked.
    I've had trouble with mica insulators and a tiny spec of solder :-(

  • @justinhiggins2210
    @justinhiggins2210 Před 3 lety +2

    A good speaker can make an average amp sound great, no amp no matter what the cost can make a bad speaker sound good.

    • @tyronenelson9124
      @tyronenelson9124 Před 3 lety

      Its not the equipment you use, its how you set it up that matters.

    • @lunam7249
      @lunam7249 Před rokem

      a good speaker and a good bgw amp can make you wet your diaper😂😂😂from pleasure

  • @coldfinger459sub0
    @coldfinger459sub0 Před 3 lety +1

    Cool history movie amp.

  • @pliedtka
    @pliedtka Před 3 lety

    Lucky again. Maybe cold solder, maybe oxydation on the plug/socket connection. I hate when the output section blows - it can take with it drivers, predrivers, VAS, voltage bias section 🥴🤬. This one has current limiter, so it would be hard to blow the OS. But try to get parts for some of the older gear, yeah.
    Now in the same chassis you can find 5kW of class D, but they're almost unfixable. I heard the N Cores from Hypex, very clean, high resolution amp. And my other friend picked up 2ch Pascals boards to try - integrated PS, bla, bla, but everything SMD.

    • @12voltvids
      @12voltvids  Před 3 lety

      Yup class D are certainly powerful and efficient. I still prefer the sound from my 40 watt vacuum tube amp. Mind you a tube amp requires very good efficient speakers and these days getting good efficient speakers cost an arm and leg.

  • @waynemckinnon1238
    @waynemckinnon1238 Před 3 lety +2

    Wow, Dave...I knew you were good but now you've entered the realm of "Magic". Just looking at a piece and laying hands on it is enough for the cure!! Hallelujah. And Thanks...
    BTW, it's: .1% THD for 225 watts per channel, 20 to 20,000 hz, both channels driven at full volume, with 2 volts input. Guaranteed no more than...
    Anything less, the distortion falls to very competitive numbers. In the .02 and less range. And...anyway, I doubt I'll ever make it sweat that much.
    You should hear it drive a pair of Magnepans, a notoriously difficult speaker for an amp to control.
    Enough, I'm beginning to sound like I'm defending my girlfriend. Thanks for saving her, Dave

    • @lunam7249
      @lunam7249 Před rokem

      that amp does really around 300wrms into 8 ohms x 2 chann !!😮

  • @zachnorton5233
    @zachnorton5233 Před 2 lety

    I have seen those wires going into the sound board's cannon plugs come loose from the plug. Maybe could contribute to the fault?

  • @frankreiserm.s.8039
    @frankreiserm.s.8039 Před 3 lety

    Why did you not hook it up to your function generator and scope? Not related to this video with its TO-3s, how do you quickly check TO82 BJTs in circuit to make sure that they are probably good?

  • @MarkCross62
    @MarkCross62 Před 2 lety

    Got several BGWs, my dad had a 1000, their first if I’m not mistaken. I have a 750g from 89’ that just started flashing idle lights on power up I can’t seem to fix. Need someone with some expertise.

  • @frankreiserm.s.8039
    @frankreiserm.s.8039 Před 3 lety

    When you disconnect your your speakers, why do you not have to insert a dummy load into the speaker outputs of the amp?

  • @laszlosokolai2858
    @laszlosokolai2858 Před 22 dny

    This is built like my threshold stasis

  • @technixbul
    @technixbul Před 3 lety

    I had the same problem 10 years ago, when you listen to quiet music it works perfectly when you turn the volume up under load and heat builds up, some of the end transistors defected and stuck closed and stay closed until the amp is energised and hot. That defect is extremely hard to find ... it took me half week to catch it and test transistors under load separate from the amp to see which one sticks.

    • @rogertyler3237
      @rogertyler3237 Před 3 lety

      No When That Equipment Is That Old
      It's Time To EOL It.

  • @russellhltn1396
    @russellhltn1396 Před 3 lety

    A big amp like that would be great for subs or the wolfer of a bi-amp design. I'd think low distortion wouldn't be as critical there.

    • @12voltvids
      @12voltvids  Před 3 lety +1

      That what they were used for in the movie theatres. Subs where distortion won't be noticed. Actually in any high power application because the ear doesn't detect distortion as easily at high volumes anyway.

  • @MrRadioGypsy
    @MrRadioGypsy Před 3 lety +2

    I was suspecting a fault on the relay board itself, creating its own 'false protection fault'.

    • @davidwaits9685
      @davidwaits9685 Před 3 lety

      Thank you, I am pulling out my 750c tonight and repairing it!

  • @MrMaxeemum
    @MrMaxeemum Před 3 lety

    I'm surprised you didn't clean up the plug and sockets. I suppose the act of unplugging and plugging them in again would clean up the contacts a bit but why not clean them while you are there especially if you suspected a bad contact? I'm not having a go at you it's just an observation and would love to hear your thoughts on that repair. Keep up the good work.

    • @12voltvids
      @12voltvids  Před 3 lety

      The mechanal action of unplugging and reconnecting will clean the connection.

    • @MrMaxeemum
      @MrMaxeemum Před 3 lety +2

      @@12voltvids Agreed but a little deoxit a brush and multiple insertions would have helped. Again, I'm not having a go, it's just a thought. I totally respect your work and I bow to your knowledge of older equipment. It's hard to get my true thoughts across in such short conversations without sounding abrupt, I promise you that is not my intention. Peace.

  • @giorgostexnikos6976
    @giorgostexnikos6976 Před 3 lety

    excellent video

  • @reginaldlawrence412
    @reginaldlawrence412 Před 3 lety

    I always liked that earthquake movie.

    • @FOH3663
      @FOH3663 Před 3 lety

      Indeed!
      The real star was the incredible 4x4 Chevy Blazer Charlton Heston drove around.

  • @waynepollard6879
    @waynepollard6879 Před 3 lety

    Just wondering if the pins were marking good contact !

  • @joelarthurs7552
    @joelarthurs7552 Před 3 lety

    Good work Brother

  • @jaceknasalski1422
    @jaceknasalski1422 Před 3 lety

    Nice beast! Just for a party in small apartment :) . Btw what is the maximum power you can draw from a regular power outlet in North America?

    • @12voltvids
      @12voltvids  Před 3 lety +1

      Standard outlet 15 amps for 120v, however there are higher 20 amp circuits for certain applications.

    • @jaceknasalski1422
      @jaceknasalski1422 Před 3 lety

      @@12voltvids thanks! In Europe (not UK) it is 3680 VA (230V x 16A).

    • @eDoc2020
      @eDoc2020 Před 3 lety

      While the outlets are 15 amps / 1800w it's worth noting that continuous loads can only draw 12 amps RMS. Alec from Technology Connections did a video about Space Heater Nonsense. The short version is they're virtually all rated 1500 watts.

    • @hubzcaps
      @hubzcaps Před 3 lety

      1.5KW

    • @FOH3663
      @FOH3663 Před 3 lety

      The maximum amount of power you can draw?
      𝟭𝟬𝟬𝗮𝗺𝗽𝘀 for a couple seconds.
      To avoid nuisance tripping, a breaker will pass extra-ordinary amounts of current for surprisingly long periods of time.
      A 20 amp circuit can pass 7-8 times the rated 20amp trip amount, ... for up to a second or more.
      It will allow up to 3x the rated amount for up to 10sec or so.
      It can allow up to 1.5x, to 2x the rated amount for a period extending as long as 30 seconds!
      Thats;
      𝟭𝟬𝟬𝗮𝗺𝗽𝘀 𝗳𝗼𝗿 𝗮𝗿𝗼𝘂𝗻𝗱 𝟭-𝟮 𝘀𝗲𝗰𝗼𝗻𝗱𝘀, 𝗮𝗯𝗼𝘂𝘁 𝟲𝟬𝗮𝗺𝗽𝘀 𝗳𝗼𝗿 𝗮𝗿𝗼𝘂𝗻𝗱 𝟭𝟬 𝘀𝗲𝗰𝗼𝗻𝗱𝘀, 𝗮𝗻𝗱 𝘁𝗵𝗲 𝗰𝗶𝗿𝗰𝘂𝗶𝘁 𝘄𝗶𝗹𝗹 𝗮𝗹𝗹𝗼𝘄 𝟯𝟬-𝟰𝟬𝗮𝗺𝗽𝘀 𝗳𝗼𝗿 𝗮𝘀 𝗹𝗼𝗻𝗴 𝗮𝘀 𝟯𝟬 𝘀𝗲𝗰𝗼𝗻𝗱𝘀!
      All from a 20 circuit!

  • @minnesota-boston9620
    @minnesota-boston9620 Před 3 lety

    Wow, good job.

  • @cocosloan3748
    @cocosloan3748 Před 3 lety

    OP amp +drivers + parallel output transistors and output current protection and thats it ? Result - distorted sound AF :)

    • @12voltvids
      @12voltvids  Před 3 lety

      Not the cleanest sound but bipolar transistors like bipolar people are a little distorted anyway.

  • @JoseAlvarez-bs8js
    @JoseAlvarez-bs8js Před 3 lety

    Good job

  • @OGmolton1
    @OGmolton1 Před 3 lety

    is it possible whatever protection circuit it has just needed to be reset somehow and unplugging that channel did the trick?

    • @12voltvids
      @12voltvids  Před 3 lety +1

      No, any protection circuit would reset as soon as power removed. These type of Amps don't have any logic. They monitor for any DC voltage on output and if any detected it opens the speaker relay. Once the voltage goes away the relay closes.

  • @stphinkle
    @stphinkle Před 3 lety

    Wonder if that type of amp would make a good PA amp for bands or performing arts.

    • @12voltvids
      @12voltvids  Před 3 lety

      Yes you can beat on it all night. Many clubs and bars use these type of Amps.

  • @russellhltn1396
    @russellhltn1396 Před 3 lety

    My theory is that you had a weak solder joint that caved under the surge of that loud "pop". Resoldering fixed it.

    • @12voltvids
      @12voltvids  Před 3 lety

      Possible or the plug connection failed.

  • @Bushougoma
    @Bushougoma Před 3 lety

    How dare that weak breaker trip having to cope with the inrush of that beer can sized filter cap :-).

    • @12voltvids
      @12voltvids  Před 3 lety

      With the lights on, they draw about 650 watts for the studio lights and the inrush from firing this brute up no wonder the breaker tripped. I have 2 circuits in the garage. Lights and garage opener on 1 and bench on the other. Plus 2 240 plugs for my car charger and heat. Draw lots of amps in here.

  • @harryconover289
    @harryconover289 Před 3 lety

    The switch to put in mono is likely the problem Clean its contacts

  • @electron0002
    @electron0002 Před 3 lety +1

    I would of stuck the diagram under the lid for the next time in for repair

  • @lunam7249
    @lunam7249 Před rokem

    3000 watts of mosfets!!! 150watts x 12 per channel!

  • @jasonthejawman5442
    @jasonthejawman5442 Před 3 lety

    I remember this music bakery this song

  • @bujfvjg7222
    @bujfvjg7222 Před 3 lety

    155v? You should see me wondering about attempting to bias my 100w valve amplifier with 460v across the rail!....

    • @12voltvids
      @12voltvids  Před 3 lety

      That's easy as you are just looking at the voltage drop across the kathode resistor.

  • @JasonHalversonjaydog
    @JasonHalversonjaydog Před 3 lety

    yeah on 120 volts that'll draw about 6 amps at 750 watts

    • @12voltvids
      @12voltvids  Před 3 lety +1

      Inrush is probably closer to 15.

    • @eDoc2020
      @eDoc2020 Před 3 lety

      That's assuming 100% efficiency and perfect power factor. In reality around 75% amp efficiency and 0.75 PF is reasonable, so it's more like 12 amps draw. Definitely overkill for a home theater.

    • @FOH3663
      @FOH3663 Před 3 lety +1

      @@eDoc2020
      Overkill is certainly relative.
      However, for subwoofer duty, and to adequately track the big pulses of low freqs that accompany the deepest effects, not overkill at all.
      Actually, it's likely inadequate.
      To maintain the same dB level, a subwoofer driver requires a 4x increase in excursion for every octave downward. That multiplies quite quickly.
      Plus, our hearing requires significant additional dB levels as the freqs extend lower.
      For 90dB@40hz, we require 18dB more to hear the same relative loudness @20hz.
      18dB = 64x increase in power!
      So, especially in the home theater, subwoofer realm, it's not overkill.

    • @lunam7249
      @lunam7249 Před rokem

      that amp can pull around 15 amperes...10 continous...for sure, in music stadium

  • @GeorgeGeorge-xj2bc
    @GeorgeGeorge-xj2bc Před 3 lety +1

    The worst failures are when replacing output transistors and have missed to find out a burned kilohm resistor somewhere in the driving circuit or a leakage small transistor or a burned pcb trace that is not visible and when test it blows again with flash light in the fuses along with the short circuit sound.And have lost money with a couple of hours and then start again from zero.Freaking experiences.

    • @12voltvids
      @12voltvids  Před 3 lety

      Yup always quote double the price for parts just incase they all have to be changed again and get a deposit in advance.

    • @eDoc2020
      @eDoc2020 Před 3 lety

      That's why it's a good idea to use a series lightbulb when working on power electronics. It won't protect everything but it should help save the big expensive parts.

  • @moodyga40
    @moodyga40 Před 3 lety

    good amp i owned one

  • @stopthephilosophicalzombie9017

    How do you drain the capacitors?

    • @12voltvids
      @12voltvids  Před 3 lety

      Turn off the power.

    • @stopthephilosophicalzombie9017
      @stopthephilosophicalzombie9017 Před 3 lety

      @@12voltvids Then why are people always warning you not to shock yourself on capacitors of unplugged equipment? You really do have a way of being an unhelpful smartass.

    • @12voltvids
      @12voltvids  Před 3 lety

      Any properly designed equipment will have resistors across the caps to discharge them when power is removed. Tube gear is different. They use high voltage and the caps can hold a charge so you need to discharge with a resistor or throw a screwdriver across and draw sparks.

    • @solitaire5142
      @solitaire5142 Před 3 lety

      There is a draining resistor mounted on the chassis between the filter caps

    • @12voltvids
      @12voltvids  Před 3 lety

      @@solitaire5142
      This is to protect the op amps from damage from loss of one of the rails. This ensures that both + and - rails are fully discharged.

  • @graboid116
    @graboid116 Před 3 lety

    At 31:44 sounded like a drum solo or something

  • @Synthematix
    @Synthematix Před 3 lety +1

    Youre brave messing with this, one mistake and youre dead

    • @12voltvids
      @12voltvids  Před 3 lety +1

      It's really not that bad. I'm a professional remember. I am aware of the risks and take all precautions.

  • @PhuckHue2
    @PhuckHue2 Před 3 lety

    silver micas. nice

  • @sirsuse
    @sirsuse Před 3 lety

    I really hate when the happens. You don't really know if you actually fixed the issue.

    • @12voltvids
      @12voltvids  Před 3 lety

      It's a pita when it happens. Suspect it was the connector as that was all that was faulty.

    • @sirsuse
      @sirsuse Před 3 lety

      @@12voltvids Very good chance. It is a beast! Love it!

  • @fagundesmartins7061
    @fagundesmartins7061 Před rokem

    repair ok best

  • @emilvladoiu91
    @emilvladoiu91 Před 3 lety +1

    Dude...just remove that metal can opamp,fit a new dip8 socket and fit a new opamp,you could use: LM318,LF351n,NE5534 and god knows how many more lol,how to say that you can't fix it if the opamp is dead?!?! Come on man....i moddified my BGW a lot,change also the supply zenners for the opamp with lower voltage as the opamp on these amps ar powered to maximum +-20vcc and in case of a shock they will die,i reduced the opamp voltage in mine to +-5VCC and use a LF351N,no problems ever since,don't you ever say that you cannot fix something,there are thousands of ways to fix something,and these old designs are toys for me,i don't even need schematics for them,so be a pro,not a amature.

    • @12voltvids
      @12voltvids  Před 3 lety

      Op amp is fine. Not about to change something on spec. Perhaps you would and then change the customer only to have a pissed off customer when it breaks again. I hand back no change because it didn't fail. When it came back it the fault remained long enough to find the fault in the speaker protection circuit. This is why I have very loyal customers that constantly bring me stuff. Because i don't charge them 95 to do a "diagnostic' and even when it works find something to change to justify that charge only to have it break down because that guess didn't fix the intermittent. I only change parts after I can demonstrate the fault or if it is a catastrophic failure. Same as I don't shotgun cap replacements. That is a sure sign of an amateur that doesn't understand how they work and how they fail.

    • @emilvladoiu91
      @emilvladoiu91 Před 3 lety

      @@12voltvids You can always make them better,if you know the parts,you know the specs then is easy to make them unbreakabile,you should know that op is on is full rated voltage and that will kill him,changeing two zenner wont kill anyone and the opamp will say thank you,but your interest is to get damaged sooner or later...more money for you,i get the ideea,what about the customer?? they have no fking ideea what's inside of a amp or how it works so i really don't care about that,if they know better than me,i suggest them to fix them by themself,none of my amps that i fixed or moddified in the last 15 years failed,not even one of them,good parts ar indeed exepensive,but i respect myself and my work.

    • @12voltvids
      @12voltvids  Před 3 lety

      @@emilvladoiu91 they are operated at the designed voltage for a reason. Changing to a lower voltage for op amp will also change the charastics of the sound. Running a component at the max spec voltage will not shorten it's life. They have a designed operating voltage and that designed maximum operating voltage is still well below the voltage that will damage the component. Over current on the other hand will damage the device as current equals heat and heat damages parts but you already know this. There is a difference between max operational voltage and absolute maximum voltage. Many designs do operate close to the max operational voltage, right up to the limit. This is where the device is at its most efficient, signal to noise ratio of the highest, linearity at the highest. This is why they run them there. Changing the zener to a lower value because you think that will prolong the life of a part is nonsence. It lowers the dynamic range and the signal to noise ratio. Modders think they can outsmart the engineer that designed it. The engineer did the calculations. The exception is when the engineer makes a design change when a problem crops up and the factory issues a service bulletin.

    • @emilvladoiu91
      @emilvladoiu91 Před 3 lety +1

      Then can you explain why more then 80% of the bgw-s faults lays in the faulty op-amp's and blown outputs?? so in your opinion you should drive all the op amps and the semiconductors to maximum voltage....now i see why your amplifiers fails and mine doesn't.
      You speak about SNR on a power amp?!? I hope this was a joke....like someone will keep an almost 1kw amplifier as headphone amplifier to keep an eye on SNR ratio.
      My goal is to make an amplifier bulletproof,Crown Macrotech's have 100Db SNR,this one have 106Db,do you think that my low voltage op now will loose more than 6Db ??? i don't think so....so is at least as better as a proper Crown Macrotech from this point of view but now is stabile and no more fried op amps on my BGW's.

    • @12voltvids
      @12voltvids  Před 3 lety +1

      @@emilvladoiu91 blown outputs generally from overloading the output.
      Many of those faults with the op amps were not because of over voltage due to the design they were over voltage due to the zener diode failing and going open, or the solder connections to the zener breaking down due to thermal stresses from repeated heating and cooling. When the connection fails the zener might as well not be there and full supply voltage kills the op amp. When I was in the business I saw so many failed amps that were caused by broken solder connections in the driver stage. Changing to a lower voltage zener won't do you any good if the zener goes open or the solder fails on it. This app had no problem in the amplifier board the problem ended up being on the relay. Broken solder the number one problem with most electronics. Cracks solder or cold solder is the number one cause of component failure other than user error for example shorted speaker wires.

  • @danielsaturnino5715
    @danielsaturnino5715 Před 3 lety +2

    Vintage smd tech :)

  • @jeffclark5206
    @jeffclark5206 Před 3 lety

    I swear I see a cheap 2 prong power brick inside there in the mess of wires.

    • @12voltvids
      @12voltvids  Před 3 lety +2

      Yup that is a cheap power brick i put in several years ago to run the quiet fan because the original one sounded like a jet engine.

    • @jeffclark5206
      @jeffclark5206 Před 3 lety

      @@12voltvids as long as it works right lol

  • @stphinkle
    @stphinkle Před 3 lety

    Looks like your meter needs a new battery.

    • @12voltvids
      @12voltvids  Před 3 lety

      Yup it does. Pandemic remember. I avoid going to stores unless i have to. Bas enough i have to work in people's homes with full ppe on.

    • @eDoc2020
      @eDoc2020 Před 3 lety

      At least it's a Fluke so it should shut down before it malfunctions. Cheap DMMs like I have read high as the batteries go. I don't know how long it took me struggling with a 5v supply that was reading 8v. I even replaced the TL431 because it wasn't conducting even though the input appeared to be well over 2.5v. After that I've been more careful.

    • @12voltvids
      @12voltvids  Před 3 lety

      @@eDoc2020
      It will be a fluke if it is accurate when the battery gets too low, and no it doesn't shut down but the display starts to fade and then the readings go out.

  • @rogertyler3237
    @rogertyler3237 Před 3 lety

    Might As Well Tell The Owner To EOL It

    • @12voltvids
      @12voltvids  Před 3 lety

      Why would he do that?

    • @rogertyler3237
      @rogertyler3237 Před 3 lety

      @@12voltvids sometimes
      Those Old 70's Amps
      & Receivers Aren't
      Worth Fixing.
      If The Parts Are
      Obsolete.
      I Remember I Had
      An Old 7p,s Yamaha Stereo
      Receiver The Power Supply Was Bad &
      I Called About A New one
      & It Cost More
      Then It Was Worth. So
      So I EOL'D it.

    • @12voltvids
      @12voltvids  Před 3 lety

      @@rogertyler3237 only when parts unavailable.

    • @rogertyler3237
      @rogertyler3237 Před 3 lety

      @@12voltvids I Found All Kinds Of
      Led TV Parts On Amazon. I Didn't
      Think They Had All Those Parts.
      Well At least I Know Where To Go
      To Get A Parts If I Need Them.