How to troubleshoot noise Harmony 415 guitar amplifier Tube Amp Theater 70's Japan retro

This amp was delivered to D-Lab with many issues. Reports of noise, low power, humming, popping lightning crashes. You name it, this one suffers from them all. After some investigation, turns out the man filter cap was leaking, input jacks were corroded, Some mis-wiring, somewhat of a mess. In this video I have corrected the main violators. There is still more to do. When complete, I will have the owner demo the new rebuilt and clean sounding machine. Yes, it has been a long time since Tube Amp Theater has aired. More to come soon, I promise. TD

[@russianvideovlogguy]

I love uncle doug he is the reason I built my first tube amp but your channel actually shows you the procedure & I really appreciate that.

[@audiotechlabs4650]

If you don't have humor, what the hell do you have? To laugh is to live! Great service on this jewel, Terry! The owner will be thrilled! I presume the power cord was correctly changed to a 3 prong. Replacement of inferior parts can make this amp be a great player amp for the next 20 years! Love the tube videos! Thanxz

[@d-labelectronics]

Thank you my friend, Part 2 is loading right now, follow up on noise

[@jessferrera3155]

Looks like that Harmony build from the factory - back in the day, had a few design flaws. Lucky for this old amp, it ended up on D-Lab’s bench and now it’s all fixed up. Another fine repair demonstration. Cheers

[@jjsant3250]

I have the same amp. I changed those input jacks as well as the usual stuff. Also did the coupler caps. Some were leaking dc. Original Jensens. Build a cab from pine since the 1967 and newer, like mine, are that pressed cardboard garbage. Guitologist did a 1966 that was real wood. As Terry mentioned, taking out the baffle is needed to get the chassis out which is a PITA. Excellent amp once given some TLC.

[@sski]

You crack me so consistently, up. Especially that ending. Great job on the amp. But where did the hum go? Hmmmmm, tis a mystery.

[@83roadstar]

Love the Vintage Harmony,great repair Terry.

[@sarcophagist4097]

Let's hope the owner will agree to have the input jacks replaced. Would love to see a Part 2 video featuring replacing those jacks, along with installing the mp3-player input.

[@d-labelectronics]

Yes, will do

[@cheycasters]

Dang Terry, you are amazing man!!! And a nut bag too boot ;) I love it!

[@BlueberryStinkFinger62]

Dont forget Alcoholic

[@Finom1]

Terry, Bless you for sharing your wisdom with us!!!

[@gordonsheard8029]

Always educational and entertaining.

[@ralphmadera4366]

Besides being a knowledgeable person, you also crack me up must of the time. Thanks

[@d-labelectronics]

Thank you my friend, I try to keep the vids fun

[@barbmelle3136]

From Leo: I'll share a tip that has worked for me since the early 1970's; Get a .30 caliber brass brush for cleaning rifle barrels. That really helps clean up the 1/4" jacks on music equipment, especially the sleeves. The only drawback is that you need to check after brushing and make sure no brass bristles fall into anything.

[@donstewart368]

He drinks wine while working on them. I drink jack and coke while watching. Yum

[@TheGuitologist]

This is one I used to own and sold. It was a minimal service for sale situation. Trying to be respectful of the vintage at the time. The two changed resistors were my work, but looks like someone else came behind me and tacked in that electrolytic cap and installed those orange drops. That resistor you thought was a 100 ohm should have actually been a 1k. I upped the value to a 1K 2W. You can see my video on it below: kzbin.info/www/bejne/nn7GlISVpLeYqbs

[@d-labelectronics]

Hey man, Yep, your right it is a 1K. (Just measured it, around 970 ohms now) The red band just darkened from heating. I'll check out the video. Plan to shoot a part 2 after I change the input jacks, might totally re-cap if the owner wishes. Great vintage amp for presentation. 1st one I have ever worked on. Not a big fan of the particle wood speaker baffle board. Must have been the thing back then. Thanks for the added info, I will take a look at the vid. TD

[@_Ramen-Vac_]

Mad. Laughed me bluddy butt off. Great sounding amp resurrected. Tip of the ballcap, Sir!

[@d-labelectronics]

Thank you Sir, glad you liked. I try to shake things up a bit

[@rciancia]

Instead of Full Metal Jacket, we have Heavy Metal Jacket starring Terry D. Excellence overview as usual ... good stuff bro

[@d-labelectronics]

Thanks man, Tube Amp Theater is my fav. Had to do the Harmony justice.

[@renegade44040]

Fixed this one up rather nicely.

[@danielgendron6344]

"Ménage à trois" could be a good relief when "ménage à deux" becomes routine...;)

[@jvin248]

I got tired of banging around the guitar doing that kind of testing .. so I grabbed some scrap parts and have a pickup, a couple of guitar strings on old tuners and a jack on a small 6x10 footprint board. That way I can plink and strum some noise into an amp -- and I don't get distracted actually playing guitar :) When I rework it I may add a humbucker pickup and a switch with the single coil pickup on it to add that test in.

[@smstiao-tecnologia]

Hello Tery, these guitars have two things that also disturb me: 1- the strings and 2- the strings. I would love to learn to play them just to test the amplifiers !!!

[@barbmelle3136]

From Leo: Technical Question: Have you ever converted the filament supply for the pre-amp oand inverter tubes to DC power? It would seem that taking any 60 cycle AC away from the preamp tubes would help clean up the signal.

[@kenwhelan3003]

Its a blend of three grapes..luv your vintage test equipment I see the obvious Tec 2213 T935A The new Hioki What are the other two stacked on the bench no names on the faceplate Thank you tube amp theater

[@caspianwendell]

I hooked up a fender that was popping the way you do it and I can hear, (and see) noise from volume pot to 12ax7, have changed pot, tube, resoldered all connections and nothing helps...what now?

[@fabinhoosmar]

Mais um bom trabalho colega, você faz o correto......É tão simples retirar a caneca eletrolítica estragada e fazer a substituição, serviço limpo e bem feito, mas parece que a a maioria dos técnicos tem PREGUIÇA, soldando um eletrolítico em cima do outro....nunca fiz isso......Parabéns pelo exemplo de como fazer o correto !!!!!

[@dennisperusse3837]

I could be mistaken but I think that the person who put in the 100 ohm resistors was trying to do what the Vox AC-15 has on it which was similar.

[@Yes-ok1tl]

Hey Terry, here's a tip from Leo Fender, circa 1955 (he couldn't play guitar either): Have someone tune that guitar to "open G" tuning. That way, when you strum the thing, it'll make a chord instead of random notes. Your wife (and anyone within earshot) will thank you.

[@ablacon64]

Very nice video! I fix laptop motherboards for a living but I love audio equipment! Someday I'll switch to it! ;)

[@ablacon64]

BTW, what product did you use to clean the cap region (the black bottle at 8:22)?

[@JulianA-tr6pt]

@@ablacon64 It's isopropyl alcohol

[@ablacon64]

@@JulianA-tr6pt Thank you! I use it too! But never seen it in a black bottle, in Brazil there's a glass bottle (best quality) or plastic white bottle (most common).

[@TheRoiderien]

I would have changed out the paper caps--especially if they were connected to any of the grids--cheap insurance. Also, did you test for output power? A pair of 6BQ5s/El84s should put out around a clean 15 watts or so.

[@russellesimonetta3835]

Beautiful speakers!!!

[@RobertKohut]

Nice!! Great job. Nice wine glass, perfect compliment to some great coasters... :-)

[@d-labelectronics]

Yes Sir, The coasters are a great addition to Tube Amp Theater! I appreciate your contribution. TD

[@PaintmanJohn]

Terry. QUIT WASTING THAT DAMN WINE ! Your 'poor ' wife would REALLY appreciate you "SHARING" those bottles :-)

[@billdyke9745]

She prefers beer...

[@davidsigglekow1349]

You’re a fine guitar player Terry. don’t sell yourself short

[@raulmontesdeoca7843]

Great job Terri keep it up.

[@kxmrock]

You got me to Buy solder wick couple years ago, good stuff

[@roncarter2188]

Terry well done, I hear Boones Farm is good to clean input jacks with..........

[@WS-ij1fu]

I'll bet your high school French teacher remembers you fondly !

[@d-labelectronics]

He was actually my Chess Instructor, never smart enough to learn a foreign language : )

[@WS-ij1fu]

@@d-labelectronics My French teacher wasn't smart enough to teach me chess, he wasn't that great at French either, having learned his marching through France shooting Germans

[@SIXSTRING63]

Man, love working on this old amps. So much easier to troubleshoot and replace parts. Got a modern Marshall DSL 20 on my bench right now making that same sound on the gain channel. Nothing that will change with any probing. It’s in the preamp on V2 but it’s one of those wonderful dual sided circus boards with via’s from one side to the other. Fun to test anything NOT. With relays and digital Reverb it is a pain. Schematic has been revised about 9 times since it was manufactured. Added parts from the new rev schem that this didn’t, still making noise. Think I have it narrowed down to a filter cap, has 120hz at about 2vac at that node for the first plate a v2. Change those out tomorrow. From what I’ve read on the Marshall forums some folks went through getting 3 or 4 of these before that got one that worked right. Bad components and or bad design. Just like the TSL 100 amps that had pcb material that became conductive with heat that would bleed voltage from the screen grid to the control grid and just reek havoc with thermal bias runaway. Another issue Marshall would not admit or fix. They would let you buy the updated pcb at about $250 shipped to the states. Thankfully this smart German tech figured a good workaround to isolate those two pins from each other. I’ve fixed 5 so far and all work perfect. One cat had his amp collecting dust for ten years because of roasting output tubes, he has not had an issue in 3 years sine I did the mod. Love your videos Terry, humor, wine and cool repairs. You and Uncle Doug are my top 2 amp channel guys. If you want to see some cool test equipment torture testing and mods check out Joe Smiths channel. He has the best electrical engineering chops of anyone I’ve ever come across. Some of the stuff he builds to run his tests are just mind blowing. Thanks to all you guys who share the knowledge. I’ve become a pretty good tech from good books and good teachers like yourself and the others I’ve mentioned. I was in the mechanical engineering trade for 30 years. Started this as a hobby to take care of my own gigging gear, now it has become a full time endeavor.

[@mattjwayad9639]

I love you D-Lab. May I send you a corkscrew with a foil cutter? It will yield a no-distortion pour. ;)

[@vsmichael1]

I fix a lot of electronics but I have a issue you might help me with. I have a HK A300 tube amp and I've checked the tubes and they are good but the left channel has very low volume & its distorted. Amps been unused from 1969 to now , it was put in a console cabinet. It's sat a long time. There's a kit online for $125 with power supply caps and the other caps to replace like signal input caps .05 if @400vdc etc. is that kit a smart move to do in your opinion & any idea on my problem? Thank you. Mike in Virginia .

[@umajunkcollector]

project request: How to make a stereo to mono attenuation patch cord to go from mp3 player 3.5mm stereo earphone jack to guitar mono 1/4" input jack? What resistors would be used in the 1/4" plug to attenuate and monotise the signal? Such a special patch would be far more useful than drilling and adding another input jack. I don't know where a person may buy suck a patch cord? Terry saves the day!

[@marklenarc]

Have you ever tried mixing a little ginger ale with your wine? It's a bit pricey, but greatly improves the palatability.

[@brich2929]

where's part 2 of the King Cobbler Deluxe repair?

[@d-labelectronics]

On the way, everything is cornplete, just need someone to stop by & play it!

[@oliverisailovic]

Cheers man!

[@d-labelectronics]

Yes Sir!

[@goodun6081]

At about 6:00, if you let that non-original 100 ohm resistor continue to run really hot for a sufficient time period, it'll eventually drift upwards until it reaches 560 ohms!

[@ka2rwp]

yea menage a trois (manaj a twa) because you feel like doing so after you drink it and what the flavor and texture of the wine is like or compared to.

[@plinkleton]

you never did any measuring on that cap can to check its actual condition .

[@michaeldowning796]

you the man

[@videolabguy]

Gimme the model number of that goulish schnozola iron.... Please. I gotta get me one of those! The front bumper fell off of my Dusenberg! :-) (Manage a Troyz?? What could that possibly mean?)

[@SIXSTRING63]

videolabguy If you can’t find a big Ungar, get one of those 350watt old American Beauty irons on eBay. I got one for $50 used and it is killer for chassis soldering. They are over $200 new.

[@pneumatic00]

Another possibility for chassis soldering. Primitive but works GREAT. Get a 1/4" or 3/8" bolt, 3-4-5 inches long. Prefer non-galvanized, definitely prefer non-cadmium plated, hex head. Grab the bolt in a pair of vise-grips, and heat up the head of the bolt in a propane torch. In about 20-30 seconds it will be hot enough to solder to a steel chassis. I'm going to assume this isn't something you need very often. Garage sale also works for the cattle-prod style ones.

[@normjacques6853]

What is that audio test set, anyway??

[@d-labelectronics]

Thats a custom dummy load test set. I made 6 of them. Great for audio amp servicing

[@gearheadted9210]

dude you're wacked but i like it and you know your stuff!

[@d-labelectronics]

Thanks man, Im actually a pretty boring corporate america guy : (

[@evananderson8452]

The Harmonious Blacksmith. Great Choice. France, Wine Country. Menage a Trois = Group of Three

[@waynewayne3709]

Cap strapping is bad and lazy practice.. D lab will sorted it. Over here in Scotland (England) many years I pop into a repair shop with a fender amp for repair as it needed it's main cap had some probs and the tech said to me.. We refill capacitors and its going to be a pricey job.. As a tech myself I said I normally just replace them.... Mm, well I've not got time for this and sits back to read the news paper.. Oh the joys

[@tiki_trash]

Nice jacket, Terry.

[@d-labelectronics]

Fits the part huh?

[@tiki_trash]

@@d-labelectronics It makes you Look Sharp!, lol.

[@danielsaturnino5715]

What about the mp3 input?

[@mike60510]

I was wondering about that. What would be the best strategy for installing that? Would you wire it into the first stage of the preamp?

[@d-labelectronics]

That will be covered in part 2, need to get the amp 100% first

[@danielsaturnino5715]

Ahhh ok. I'm looking foward for that. Thanks

[@WillyMcCoy50]

Brad sent me.

[@ricsut515]

I would NOT have used a can filter cap with lower capacitance than the factory spec. If the exact match is not available ALWAYS go higher in capacitance and/or voltage. In this application I use the CE Mfg., 525V, 80/40/30/20uF. The original was 400V 40/20/20/50. Yes you will need to re-route the wiring to put the old 50mf to the new 80mf and the second stage 12AX7 old 20mF to the new 30mf. Match the old and new 40mf and 20mf. If you do not follow this you should get assistance from a trained technician. Always be safe and do not do something if you do not completely understand the circuit and its functions. RS Silentsound

[@marks5816]

where is your tie

[@cchavez248]

Hooked up accrost! 😁

[@lincolnmicrophonellc]

manage a troys, classic

[@russellesimonetta3835]

Get tony to show you how to tune up an open E or D. Instant blues player!

[@misterhat5823]

A 300W Weller soldering gun will solder that ground connection.

[@xnotx2]

I'm sending you a pipe and some tobacco for Christmas 😂

[@d-labelectronics]

That would be a great prop for Tube Amp Theater!

[@raulmontesdeoca7843]

The wine is pronounced Minaj a twa. Lol.

[@d-labelectronics]

Roger that Sir, I knew but wanted to throw out some bait!

[@pneumatic00]

Please don't let that one out of your shop without changing out the 100K plate resistors in the preamp stages to 2-3 watt metal films. Also; one these days you're gonna bust those Hakko flushcutters cutting stuff that's too big. Thanks, Terry!

[@d-labelectronics]

Yes, I agree, lots more to do, This was just the initial shakedown. Part 2 will wrap things up. TD

[@pneumatic00]

@@d-labelectronics I hope you believe me about the 100K plate R's. Especially on this amp, those carbon comp plate resistors are +/- 20% with no tolerance band and get super noisy after so many years. Next time you get a blackface Fender amp in, do the usual filter caps, intranode voltage dropping resistors under the doghouse, 470 ohm screens, bias check, clean pots & tube sockets & check for microphonic tubes. When all those things get the amp to the best you can make it, check it out, and NOW change the 100K preamp plate resistors to metal films. The noise floor will drop to NUTHIN'. You'll be stunned what $2 in resistors can do. Once you hear the difference, you'll change those out automatically as part of your standard Fender hose-down.

[@tiki_trash]

OMG! Joe Jackson?

[@d-labelectronics]

I love JJ. Every release is different. Very talented guy. Check out his new CD, bet you'd like it

[@tiki_trash]

@@d-labelectronics I bet I would. Thanks for the "heads up!."

[@1thess523]

I actually work for a wine distributor that distributes that wine and they labeled it that because it's a blend of three grapes are there a bunch of perverts one of the two

[@ka2rwp]

you probably knew this anyway menage a trois a french word is when there is three people doing sex and may live together its a good wine, also a good wine is apothic dark walmart sells it if wallmart in your area is allowed to sell alcohol some walmarts don't otherwise you can get apothic in another store. nice to know there is another radio guy such as i that likes fine red wines.

[@mikemadden2729]

You ought to give up that wine! Have you ever considered LSD or heroin? Heroin makes you play music (or shovel snow & cut the grass etc.) better & LSD makes music sound way better! XD Ask any musician, LMAO!!!

[@d-labelectronics]

Can I buy that at my local convenience store?

[@mikemadden2729]

@@d-labelectronics, depends on who's behind the counter.

[@mikemadden2729]

Morning glory seeds contain LSD, available at your neighborhood health food store, supermarket, hardware store or Walmart, where the "associates" or "team members" are more than happy to help! *Heavenly Blue, Pearly Gates & Flying Saucers* morning glory seeds. Cool how *Our Heavenly Father named the correct varieties,* eh?

[@mikemadden2729]

30 to 40 grams of seeds, *FINELY GROUND with a COFFEE GRINDER & mixed with HONEY & CINNAMON* works really good. Then *jump in the car & crank the stereo* for about 250 miles. Coolest thing since sliced bread!

[@mikemadden2729]

In 1974 I saw Our Heavenly Father on 4 hits of supposedly weak sugarcube acid that was sold for only 50 cents a hit. He rescued me from an apocalypse of tornadoes, volcanoes & exploding atomic bombs I was driving thru! He appeared as a bright Light, like in a near death experience & as described in the Bible! I thought I'd vaporize but He shielded me, said "Don't be afraid" & fixed everything! He DID NOT say "I'll help you just this one time but never do this again" as a puny Earthling might have. He even revived my friend, who was so scared he drank a bottle of wine & passed out! He kept flopping in my lap & I had to push him outta the way 4 or 5 times as I tried to drive! I bet God laughed all the way to Wisconsin to help me out, LMAO!!!