McIntosh MC240 Amplifier Full Restoration and Recap in Detail
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- เผยแพร่เมื่อ 26 พ.ย. 2024
- BG116 - MC240 Amp Amplifier - Replacing power supply capacitors, selenium rectifier, rebuild bias supply. Replace electrolytic bypass caps, some aged coupling caps, test all 6L6GC and small signal tubes, bench test.
You are a technician expert especially services electronic audio. Thank you for sharing bro
Hello! I hope you are feeling well. This is a great video. I restored an MC40 last year and looking at a C11 preamp to refurb. You have great advice and practical intel to share, and it is most appreciated. I re-run this video as a sanity check for new projects. Thanks!
Great video ! I’m a retired electronic Engineer and own a Mc275 I purchased New 1970 . Thinking about recapping it because of the year although it sounds great . But excellent video . !!!!!
Build quality looks a lot better than the newer ones they make.
Great video for sure, it was so interesting to watch reminds me back in the days when I was learning how to fix those vacume tube amplifiers from my fanatic dad especially the Marshall band amps. And yes I still have my vacuumed amps and still love the acoustics that comes out of them. It's really ashamed that our new generations have no idea what they are missing out on this amazing technology. Thank you for this awesome video.
I love the MC240. I've been fortunate enough to work on two of them over the years. The first had the classic leaking bumblebee cap problem. The other had aging power supply 'lytics. By the way, I have a severe case of test bench equipment envy.
That old handwired stuff is the best. McIntosh uses pc boards now, like most other manufacturers. They may function the same but the mojo is in the handwiring!
Thanks for the video! Followed your advice on the selenium rectifier diode replacement and got the bias supply dead on at -46.0v.
Great video for a first look into one of these Mcintosh amps. Thanks
Good video to digest before I start on my 240 restoration
I fully restored a Tandberg Solvsuper 10 hybrid tube amplifier from 1968, it took 5 days and a lot of coffee. Only 6 watts per channel, actually gets way loud on some 70s 8 inch speakers I bought for $70, basically a $150 stereo system. The sound quality is insane, better than a $1000+ modern stereo system I heard a couple of weeks ago in a store.
Hello, what product do you use to polish, clean the exterior steel and remove the scratches?
If you ever start doing customer work again, I am in NC and I have two MC-240s and a MX-110 that most likely need to be serviced. They were serviced about 9 or 10 years ago, but have been in storage since then. I also have a new chassis for one of the MC-240s, but I know that would be a huge job.
what the song is playing in the end of video ?
You said it makes a difference in sound as to what kind of caps you use as to sound or bass. For coupling, if you use any brand of polypropylene cap with a good esr that tests good for voltage, will that sound good. Will it sound different if its polyethelyene or ceramic, oil, etc?
Nice video. I don't have very much experience with tubes, but I starting to get my interest back into the theroy
Great video !!!! The only thing I do different is I never Snip Wires I use a solder sucker. That way you don't need to Re-Strip them.I do snip those tabs.
Wow just found your video , Mac .. simply a work of art Great video
Have any spare vitamin Q capacitors?? Rebuiling my MC240.
Thanks!
very nice work. Many of the Russian ebay sellers have run out of the 600v rated K40 PIO caps, so have tried the Jupiter vintage tone, or the Jensen Copper foil caps. Some time try the MC240 with KT88s in place of the 6L6 outputs; more dynamic, with more of an ease to the sound.
You added one of the 470 ohm registor with one diode on Power rectifier mini board. How many watts 470 ohn? Is it 1watt or 2 watts or1/2 or 1/4 watt. Please let me know. Thanks.
I had a Card-Matic 121. It's a wildly different beast.
Love the channel and new subscriber. What is the brand are the Russian PIO caps?
It's easy to underestimate how much time it takes to rehab tube stuff; especially if you have a nice high-end piece and you're working in the high voltage section and you want to do a good job. It's just amazingly time-consuming.
I pulled mine out after many years with audio research pre amp .and found I had to turn the volume up alllll the way up to get the slightest sound out of it? Had phone to pre amp what would you say that is. Could you your input. Great video man thanks
That opening music was kicking!
What was that?
Great video, thanks.
Always hoping to stumble upon one of these in an estate sale....only way Ill ever afford one.
Thanks for all your work Mark.
Lee Stanford that’s how I found mine. Also had an MX110 pre-amp with it. Find of a lifetime!!
Thanks for the video. However, I notice you mention the chassis of the 240 is the same as that of the 275. I have both MC275 and MC240 so I know it is not true.
I tried a lot of tube combinations on this amplifier.....................here's one set , a combination i like very much.
5751 RCA ( black plates triple mica ) - ECC83 telefunken - 12BH7A GE - ECC83 Telefunken ( flat plates ) _7027A Sylvania .
I have an mc2115 that doesnt go pass system check when i turn it on.any suggestion what happened to it? I would like to have it repaired eventually.
Great video! I have my father's 240 and other components out for refurbishing right now. I hope they are doing as good a job! Unfortunately, mine is not near as pretty as this one. Does anyone do cosmetic restoration on these?
another great video...too bad it wasn't longer...love the older tube amps as well
Hi, love your videos, what do you think about replacing the 2 black capacitors in the voltage doubler with the authenticap 330MFD 250V instead of the 250MFD/250V?
Hi
Thank you for your generous sharing of your skills. I live in Riverside, California and have a C39 preamplifier with a “humm”. Can you refer me to a capable and ethical technician in my area?
Kind regards
Ref Tomerlin
What silicon diode did you use to replace the selenium rectifier?
I looked up the eBay price for this kit... 250 dollars is a bit of cash! Mouser has equivalents by Vishay at perhaps 40 dollars. Wouldn't look nearly as nice, however.
links?
Yeah, I'd just do a Mouser order, and I'd get the can caps from Hayseed Hamfest. Save some money. Or save a LOT of money and just use regular electrolytics under the chassis instead of can caps.
Nice work,maybe one if these days I will do mine.Any suggestions on restoring the corroded chrome?
Whats the value of main coupling caps in MC240? Is it. 47uf 600V x 4?
The centre piece of the right hand capacitor is not ground. It is 475V. This is the top capacitor in the voltage doubler. Positive terminal is B+ voltage, negative terminal is half that, which is why you need an insulated case.
your own record label? How does that work?
Whats the name of the band? sounds great.
42:56 nice quick discharge haha you touched the earth by mistake before your magic resistor pen. That was funny. Not so good for the cap though. But your making nice video's and good repairs enjoyed watching it.
101st comment, what's the artist / title of the song at the end? The Donners?
The bumblebees should all be replaced. Even if they test good they could end up failing shortly after the client gets the amp back.
@@danielthomas3057 Yeah I was thinking the same thing too. Maybe Solene or Mundorf caps perhaps? Orange drops? Trouble is, the music signal flows through theses caps, apparently contributing to the sound of the Mac. I dunno how much though. If they need to be replaced then they need to be replaced! The others, I spose if they're still good after 50 years they should probly last another 20?
Never seen one that nice!
Does anyone know the songs played at the end of the video? cheers
hell we use too ck tubes had no idea what a laptop was back in the late 70's
Another great video Mark. I have really been enjoying your videos and have learned a lot from them. I do have a question for you on capacitors substitutions. I have a bunch of new Mallory yellow caps and a bunch of orange drops for a Magnavox 8802 amp I'm recapping. Will either of them be fine or is there an advantage of one over the other?
Thanks, Tony
I imagine there is no difference in sound, as long as the specs on each cap are reasonably close. There may still not be an audible difference even if one cap has less leakage and different Q and D. As it's only 4 caps, I would do one channel with orange and one with yellow and test on a scope and load, see if there are any measurable differences while swapping pairs of tubes to cancel out the effects the tubes may have on channel imbalance. Then listen to some tunes on speakers and see what's up! Report back on Audiokarma with detailed notation of the measurements, and settle the great tube amp capacitor debate once and for all!
Probably too much error for real science, but better than people listening for differences, hours apart.
Evan Fitzgerald the caps are all the same values just rated for higher voltage. It will be an interesting test and I will put it out on AK. Thanks for the input.
Really a job for someone with too much free time, like myself during the summer. But fun!
WELL DONE
Nice video! Did you ever do a video on your variac? It looks like a custom unit. Love to see the construction details and circuit. The built in load limiter is intriguing.
rb you
42:46 No smoke ? No spark ? :)
Excellent video, thanks so much!!! 100th comment :)
Anyone knows song/artist at 58:18 ??
Why 100+100uf when the can its replacing is 100+30? Is this an error??
I like to respect and stay as close as possible to the original values, in my MC 240 i used one 100+100 µF and one 47+47 uF , both 500 VDC.
it would be a good idea to find a source of new old stock Bumble Bee capacitors as they would make the unit look authentic.
No it wouldn't. You should use modern components. You're not looking at the amp, you're listening to it, and you're relying on capacitors not to leak. You may as well leave the old ones in there if you want to just preserve the look. And not turn it on.
The Rolls-Royce of tube amplifier
Hey Mark, speaking of DeoxIt D5, who was the winner of the video contest?
don't think they have announced yet
On all the MACs, I change out those 10k/2 watts to a 10k 3 w CF and 12K / 2 watters in the phase inverter to voltage amp. I change out the 12k 2 watt PI to voltage amp resistors to 5 watt CF or WW. only reason I do is because the 2 watters always run warm to me.
Joke: How did the technician know he was doing something right? Someone sends their prized McIntosh for him to repair! Truth.
Where do you buy a kit at. Thank you
Guy only sells via ebay. Just search for MC240 power supply
You can also get can capacitors from Hayseed Hamfest. They'll make whatever you need. I just got a new one to replace the old one in a Heathkit AA32 that I have.
well done good job
Love my Mc but not one employee had white gloves during the install.....just saying.
I have 1 just found it. It turns on
good sound !!
I would never leave a single bumble bee cap in an amp.
They are terrible for reliability. Especially plate to output grid, where even a micro -amp will cook the output tubes. While I will keep an open mind regarding the tone of caps, my engineer's hat calls BS. I have never seen any compelling evidence that a good modern cap
would make any 'sonic' difference at all.
Opraser de montar um destes não tem igual, í aí Moizes Nardom.
I had to look away when you took that wire brush so close to the chrome on that chassis. yikes
Its a pretty soft brass brush, no damage done. you can hold it on your hand all day long and feel no pain
Do you know exactly which brush is? I would like to try buy the same
Tube tester is worth more than the amp...
Bumble Bees Suck people need to learn that. Theres no such thing as Mojo.
Just throw some Orange Drops in there. No one can hear those Vitamin Q caps or those PIO caps.
Woow HI-FI
The whole business of establishing a firm "physical" connection before soldering is nonsense that was taught by trade schools and in kit building instructions back in the previous century -- I know, I was there -- but, given a proper soldering job, it's totally unnecessary and just makes future repair work harder for the next tech.
This is absolutely TRUE. When I was building the Dynaco PAT-4, Dynaco absolutely admitted this in the instruction for building the 4 position "Hi Filter". There is no way the build this multi-wafer switch with that restriction. The "secure mechanical connection" procedure was an attempt to allow people with poor soldering skills to build a projects that would work. (at least to the end of the warranty.)
Wrong, solder should never be relied on for a physical connection. This is basic stuff, leads should always be wrapped first then soldered. Do it right or don't do it at all.
THE MC240 Amplifier IS A SEWWT AMP
bit overrated disappointed they didn't put any rubber grommets should have done! have you come across any Russian valve amplifiers now they should be superb. anybody!!
why did you replace the paper in oil sprigs?
Your hands dont match your voice
Cool amp indeed. But can someone tell me why people are selling these for up to 5K on EBay? Some $499, is it really worth it? With a blind test could anyone tell the difference from another way less expensive amp? I doubt it. I bet if I set my PC with my monitors, played the same media, NO-ONE could tell the difference. Never used the MC240 in this test, but a friend (an audiophile nut, who pays $276 for RCA cables, lol), we did a blind test with them and a set of $5 Phantones, he lost every test :)
Sean Spark Your friend is tone deaf. McIntosh amps are premium and have been for ages. If you compare "a complete analog" set up vs. your computer would yield much different results I'm sure. Try the Mc amp, McIntosh preamp/receiver stage with a nice turntable and some good old 4311 JBL speakers- this setup will not only blow out the windows in your home but will exhibit the warm, throbbing, spacious sound of true top quality analog gear will have you throwing your computer out of said windows.
+Patrick Foster I do agree analog has a warm feel, lived through the whole era of change, still prefer valves for my guitar amp. But I also am not opposed to the fact that good sound, is good sound. Whether it be from electrons flowing through expensive gasses, iron, or silicon, it will sound good, if both media and hardware are good. I would think the final and important factor involved is what turns those electrons to kinetic energy, the transducers. Of coarse garbage in , garbage out :) . But definitely difficult to tell the difference to the blind eye. A good digital/analog recording, tube/transistor hardware, can be hard to detect, either way. I do not lean toward either system, only a good sounding, fair priced one :)
Sean Spark Didn't know you are a guitarist, as am I. It is the age old debate really. The good old days vs. change. In reality you are correct in that the digital tech has really caught up in a sense. The "A vs. D" really started in the early 80s in the pro studios: keep using the great Studer recorders or go with the new Sony or Panasonic 48 track digital recorders that were built to fight Studer's dominance of the market. They failed. Digital recording did not make inroads into the pro studios until the rise of the pc and pro tools in particular (we'll skip the Adat crap). My friend and I have built a really nice "home" studio and I am aware of the incredible power of technology giving us poor people the chance to have our own studio that rivals some of the great old dedicated "48 track" studios! Having said all that, I would not trade my old tube Fender (my "go to" amp is an old Bassman 10, which sounds as good for guitar as it does for bass) and Marshall amps for anything. Clearly now we can see it's not A vs. D but it is A + D. Cheers!
Patrick Foster Sweet, I try, not so good, lol. Yes, I think it has become more of a football team like thing, go Digital !, Go Analog ! lol, both teams are capable of winning. I was in that flow of tech change in the 70's & 80's. Saved paper route $ for a MOOG. (never made enough). 90's were on the doorstep, as you said, home recording equipment was affordable, available, to the not so rich. SO, I too, built a home studio in efforts to setup a kind of bed & Record-fest, failed...By the turn of the century, for a few hundred bucks in a pre-amp and mics, software, a lappy, or smartphone, could make a hell of a recording. Hey, I have a pristine, very low hour ADAT XT & a Mark III for sale, if your interested.. lol :) They have been replaced by $99 hard drives and $15 SD cards.
Ah remember the ole CD burning days... another shiny coaster.
@@patrickfoster4586 Yeah, which is why when you mention double-blind testing on most audio forums you get banned. McIntosh stuff IS Premium, I know this because I've seen the price tags, but I would take the pepsi challenge against this amp with some class D stuff in my stereo, in a double blind test.