60s Harmony H400 Student Amp Gets Upgrade - I BROKE A NAIL!

In this video, we'll look at a Harmony H400A amp chassis a customer sent in. It has already been worked on a bit and there are several wiring issues we will need to address. Also, the customer sent in an isolation transformer to be installed while we're at it. Finally, we'll check out the tone and send her on her way.
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[@Jorzef2]

Hey brad love your videos, can you activate the auto subtitles please im partially deaf and they help a lot! Keep doing awesome stuff!!

[@TheGuitologist]

The only way I can see to add CC or subtitles is to transcribe them manually, which I do not have time for. Is there a channel viewer who would be willing to transcribe videos for people like Jorge? If so, please let me know, I think I can set you up with permissions to add subtitles.

[@Jorzef2]

KZbin has an automatic caption thingy, it just didnt activate on this video

[@TheGuitologist]

I usually see the CC widget on my vids, but this one doesn't have one for some reason. There's nothing I can activate. When I go to CC/subtitles for this vid, it only gives me the option of transcribing manually. I've opened up a contribution page for this video if anyone wants to help a brother out and transcribe it: kzbin.info_cs_panel?tab=2&c=UC2DDLacv42cfgT7Urv9n3dg

[@Jorzef2]

Wow thank you man! I dont mind the videos being in english Edit: The thinga magig has appeared now, thanks for the attention, and again keep sharing awesome vintage stuff with us!

[@TechGorilla1987]

I have the time to work on this. Email is in G+ profile. Be happy to help.

[@TempoDrift1480]

Creatures of the night indeed, it's 5:57 AM and I've been watching since about 11.

[@kristopher6031]

4:44 am here

[@remley8877]

Awesome idea about flipping the isolation transformer! In the 60s, most of the us power grid ran about 110v to 115 v. Nowadays,120v to 125v is standard. This amp probably sounds much more like it did when it was new and ac voltages were lower.

[@sollyharr]

Hey Brad , keep up the good work buddy, the world needs good men like yourself especially these days when it seems doing old school hands on stuff is being discouraged... I always learn something from your videos thanks !

[@danxthexman82]

I really enjoy these videos and how instinctive it is for you to work on amplification circuits. I'm sure it comes from many years of experience. Keep it up! I'm a huge fan of the channel and I learn a little every video. I own my own Remodeling business in the Lex area and don't have alot of time to research so your expertise and videos are appreciated. Thank you

[@robinaldred3255]

With you on the fingernail business. i'm a guitarist and carpenter and always seem to have at least one nail missing! I've tried using ladies false nails but, only the thumbnails seem to fit! Great channel.

[@skycarl]

Well that's one way for an amp to say" welcome back to the shop Brad."

[@jackallen6261]

Sorry about the nail. I am always very impressed by anyone that plays finger style. I had a very good friend that couldn't play with a pick and had learned from the age of 6 to play guitar (and banjo) finger style.

[@tamberp]

Staring at that schematic for a bit, I can see how it'd be possible to get away without fitting an extra in-line fuse in the original layout; but something about not having a supply fuse still seems a little dodgy, to me, though. (Probably just Brit bias, since we have fuses in the mains plug...)

[@TheGuitologist]

I should have been more clear on that...absolutely! A fuse on the primary to protect a transformer is highly advisable. The fuse on the original design is not. I used to recommend that, but stopped a while back.

[@tamberp]

Oh, yeah, with the post-rewire version, having the fuse on the primary side of the transformer would be a good thing; but I meant more that the lightbulb came on about why it's not quite as vital for the original wiring. :D

[@MarkTillotson]

Remember a fuse protects the wiring from catching fire should a short develop, which is always a good precaution!

[@williamsquires3070]

No, the generally accepted current limit for lethality is around 6 mA for an adult human, assuming it passes by the heart. The fuse is there (mostly) to protect against an electrical fire if there was a dead short across mains, excessive inrush current (i.e leaky filter caps), or wiring errors. It’s a good thing to put an isolation transformer in there!

[@DeWittPotts]

You're actually in good company with your nails. James Taylor has posted at least a couple of videos about his nail care regimen. He uses a fiberglass type overlay on his nails to keep them in playing condition.

[@SMITHII_]

Hey man, good videos. Especially cool to see these old series heater amps. One thing that you said that I and others will disagree with is, 150ma across the heart can definitely kill you. If I'm not mistaken, as little as 30ma can be leathal under the right circumstances.

[@brich2929]

thats some nice sound there. Don't underestimate Harmony amps.

[@chickengnawer]

Hey Brad-Interesting Vid! As for your Nails, U should go to a Health Food Store, and Purchase some SILICEA GEL Caplets, they're to help Strengthen Cartilage, NAILS, & Hair.

[@SciPunk215]

I spoke with the judges and you will be docked 10 points for the Kiss reference. Sorry, them's the rules.

[@kasto357]

Just wanted to say love you’re videos. You’re awesome. My two passions are guitars and electronics.

[@MrGTO-ze7vb]

Good fix..!!1 another tone box resurrected

[@madhatter57]

I have an H400. Getting an electric shock is a concern. Would replacing the two prong cord with a three prong, grounded to the metal housing, fix that ?

[@DAVIDGREGORYKERR]

There is a big plant starting up soon in Ulster called AUDEON that make HIFI equipment and guitar amps, brushing a little Epoxy resin and hardener over the area where the crack might save the tube. It might be interesting to build a Harmony amp with a Korg NU Tube for the first and second tubes as it is a duel triode and a high output PWM amp driving a 100w 4R 20" speaker with a filament supply of 3V with a B+ of 50V and 50V to drive the PWM amp just an Idea.

[@michaeldeas1969]

I miss watching your videos where you get creative and make some cool shyt. Following you on locals as well I know I'm waiting on you to build something badass. I have a 1992 fender blues DeVille 4x10 that I want to change over to point to point wiring. Thoughts?

[@TheGuitologist]

I'd probably wait until something went south first, then convert to PTP. But that's just me. There is a good starting point for something close to a lot of classic amps though. Chassis, transformers, tubes all there, etc.

[@michaeldeas1969]

@@TheGuitologist I know you're right, and I probably will wait until something goes tits up but I've been playing it for 30 years and was inspired by watching you clean up this fuster cluck 😁

[@chadmiller3535]

Nice work Brad. I just bought a Boss GT-8 pedal and I need someone to teach me how to use it. Lol. Next video I reckon.

[@TheGuitologist]

Gotta bust out that manual, dude. Those are great pedals.

[@graxjpg]

I use GT3s in my home studio for guitar and synthesizer, I absolutely love them.

[@robertgray3210]

Isn't the white wire a center tap for the reds? I think you wired the transformer to put 60 VAC on the chassis.

[@davemassie3726]

Nice Brad, Neil Young Crazy Horse Tones! SWEEET

[@AiGenerationMagic]

Great video, not sure what to make of that fizzy tone

[@audiotechlabs4650]

Glad to see you are getting well and back in the saddle! Hit one out of the park! Lots of troubleshooting info, real important before going too far on initial power up. Good info on those isolation tranys. Is there any other place in the circuit where an isolation transformer would be effective on these series filament amp circuits? In the input stage? Thankz

[@TheGuitologist]

That's what T2 is, it isolates the V1 filament from the rest of the string, reducing noise and making it safer to plug the guitar into.

[@audiotechlabs4650]

The Guitologist Right. I knew T2 was already there for safety. I just thought there was another place to put an iso-trany to keep any dangerous voltages out of the hands of the player. I must be looking too hard at it. Thanks for your reply. Thankz

[@j.asalazar9534]

I loved the manicure tutorial hahaha

[@JosephNine]

YOU CAN PICK WITH YOU RE FINGER'S AND NAIL'S , ALSO IN A PINCH THE PLASTIC CLIP THAT HOLDS THE BREAD CLOSED !!

[@paulwillett7115]

Nice job and tutorial, just got a Silvertone 5XL and found a 1420 schematic. Looking at the amp itself and comparing it to the schematic., someone has done some component changes. No isolation transformer or three prong power cord. I found the schematic via of original owners manual. Just wondering if there is a place on the internet that offers an overall upgrade modification schematic. It's easy just to install the three prong cord, but some folks just start sticking components in without the knowledge - this is meant in a very respectful way :)

[@TonyClarkGuitar]

"I get that kind of ignorant shit." Hahaha. Love it.

[@mfowler8808]

Wish I had a box full of those tube holders or make my own. So what was the 1:1 transformer voltage you mentioned it was low. I've used that same isolation transformer and just wire it up normal. My nails are so thin they tear just in normal use I can't imagine keeping long nails like that even if you do play with no pick, they would get in my way.

[@Chris66JTM45]

Good vid Brad ... Weird that the internal chassis sticker states H300A yet the external faceplate names it as H400 ??

[@TheGuitologist]

The internal sticker was something put on there by an owner, not factory.

[@scottriddle5468]

A Brad what's the deal with the Triad transformer, is it a cheap trans or what ? It seems it is if a 1 to 1 trans is that far off in voltage.

[@bazerkly907]

Reality Check: Low voltage shocks can stop your heart !

[@mischef18]

Liked this video bro. ATB

[@jimbeaux4988]

Wow. That is that coveted breakup.

[@Dennis-mq6or]

You can't properly test a power transformer like that without it's rated load on the output.

[@raymondheath7668]

Sometimes you have to wonder if a unit is worth that many man hours....

[@thomasbaker4657]

they pared their own nails .

[@simmdad]

Dangerous stuff, oh dear! Not UK PAT compatible

[@mro2112]

James Taylor keeps a woman employed whose single job is to give him fake nails for his guitar playing.

[@tomruth9487]

I was really saddened to see the collateral damage that occurred to your thumb nail. My condolences to you and your family.

[@TheGuitologist]

Recovery will be long and painful. Pray for me.

[@tomruth9487]

You will always be in my prayers.

[@chickengnawer]

: )

[@djkamilo66]

no, the tube filaments are not fuses. that is very unwise.

[@HarpinJScott]

What was the book of schematics you referenced? Looked like a good thing to have on hand...

[@TheGuitologist]

It's an early edition of "The Tube Amp Book" by Aspen Pittman: amzn.to/2DsCTGO And yes, it's a nice one to have because there are tons of Trainwreck articles and schematics that are sometimes hard to find good copies of online.

[@mfowler8808]

Tube reference book.

[@HarpinJScott]

The Guitologist Thanks Brad. I've been wanting a copy for a while. Never had a look inside... It's on my shopping list!

[@danxthexman82]

Great question

[@TheGuitologist]

Other Harmony H400 videos: kzbin.info/www/bejne/iHzWf6VqrtF8brM kzbin.info/www/bejne/n2GoZmWKqN-UidU kzbin.info/www/bejne/Zp3LgJWAjNt7hrM

[@whisk0r]

Trick for hot glue: if you hit it for a few seconds with upside down canned air, usually it will shrink, breaking any bond with the surface.

[@alexreeve]

heatshrink crew raise your lighter

[@douro20]

Also Ico-Rally wire sleeving. It's cheap and there's enough in the kit for several amp builds.

[@junkyardvinyl4811]

I'm glad I'm not the only one who bitches when a nail is broken!

[@stevenmiller5366]

Lowering the voltages.............hmmm the Brown sound!!and Lindsey Buckingham too......he doesn't use a pick that often either. Sounds good!

[@MrBugsier5]

This wiring when it came in at your place was a mess, it still is after the repair... (y would have cut everything out, put the new transformer in place of the output transformer, and put the smaller transformer on the inner side off the chassis, rewire it to standarts and it would be a nice one, it was not original at the first place, so it would not be a crime to rebuild it to nice standarts, but hey, you are not me! ) lol thumbs up!

[@KeritechElectronics]

Pity about your broken nail, I'm kinda envious for yours. Mine are short and split as fuck, so I need to nail them all the time. Nice simple little amp though.

[@ali2ndmail]

That is a surprisingly god sounding amp. You were getting some Neil Young-ish sounds from it (if that isn’t too offensive to a Southern man Lol).

[@russellhltn1396]

I think a fuse is still a good idea. If the rectifier shorts, it will get ugly. If it's a filament to cathode short, it might burn out. But if it gets gassy and does a plate to cathode arc - it's going to get fugly. I had a 5Y3 do that. Nice blue flash before the fuse popped.

[@SlightlyTechnical]

hey brad I had one of those, it had a Jenson greenback if I recall I think it was a 64 as well I would put a ts9 in front it sounded amazing

[@vintagesound5847]

I watch and like your videos, but in this one you sad too many nonsenses. Fuses, transformers...oh man.

[@TechGorilla1987]

@42:55 The only true way to undo a joint is to burn it, man...

[@williambock1821]

The tube retainers are a novel noval design! They spent the money on Sozo’s but decided to skimp on heat shrink? Ok…🤷‍♂️ NASTY nails? You have the nicest hands on KZbin,Brad!!

[@joemcgraw5529]

sounds good ,Have a H303A same layout but different cap values ill have to look into that ,it needs 3 prong cord ,fuse ,caps whole deal ,nice fix very clean no noise at all good that you put the caps close or maybe not as clean,or does the isolation trans take care of that ? mine is a 1963 model alot bigger power transformer ,maybe 1 day ill get to it had it for 40 plus years and hasnt been in working order for alot of those years but im a amp hoarder so its not a big thing right now ,nice repair really enjoyed it thanks

[@CellAmen]

Do you think an isolation transformer type variac- Single Phase ISOLATED Variable Transformer Power rating: 1200VA Input: 240 +-10% VAC Output: 0 - 250VAC Is safe enough for amp projects and mains grounded oscilloscope testing or would this still potentially damage my RIGOL oscilloscope?...

[@bobohbuboh8604]

Great tone! Very interesting thanks for your videos :)

[@cjscala87]

Wow that amp breaks up beautifully

[@TheGuitologist]

Yeah, I think so too. Great little garage tone rocker for recording.

[@RealGengarTV]

33:46 Oh no :( Now your setting your world record for longest thumbnail back months

[@RealGengarTV]

Jokes aside, is there any way one could buy/make circuit boards for old amps to remove all that wire clutter? I mean, even having all components on perf board would look cleaner right?

[@TechGorilla1987]

I'd really like to see the secondary voltage with a load attached. Open circuit testing is not ideal. Those irons are nice. Mine is a year and a half old and kicking ass. Got a 10 pack of extra Hakko tips for different applications. Got the iron for $16 and the tips for $2.

[@TheGuitologist]

Yeah, it's a steal, I think. If it lasts 6 or 8 months, I'll consider it a win for no more than I've got in it.

[@TheGuitologist]

On the secondary, you're right that voltage will come down under load, but I've done so much messing around with these amps to know that once you get up to 100V+ on a variac, the difference in output of the last few volts doesn't add much volume at the output. But it does stress the tube filaments and series resistors more and create more waste via heat. I just prefer to be safer and easier on the tube life rather than push it.

[@TechGorilla1987]

I put a tip in your last video about super gluing that plastic ring on the iron (the one just below the metal ring to fasten the tips.) Mine kept coming loose with the temperature changes. It doesn't move now. I glued it when the iron was new (and hot) and it's never backed off again.

[@TheGuitologist]

I saw that. Thanks for the tip. If mine starts doing that, I'll follow suit.

[@TechGorilla1987]

Maybe yours is built better, but from all the research I have done, the all seem to take the same replacement iron assembly. The replacement irons are about $7 to buy. Make sure the DIN pins are the same orientation (male/female aspect) when buying a replacement iron (in the event the element opens)

[@garyyarago2096]

What's up with the Led Zeppelin symbol on the yellow caps?

[@greeneterror7989]

YEAH!!

[@izzyauna8814]

Guitar or not, long nails on a man is weird. Not to mention u can’t work with them.

[@kristopher6031]

Pepsi nails

[@dp9550]

Long nails are good for picking up tiny parts too.

[@MrJohnnyDistortion]

Good thing that you didn't have to amp-utate that nail.

[@geldner]

What would the amp have sounded like without the isolation xformer? Was it really worth putting in?

[@kscotthoy]

Paint 'em or cut 'em.

[@RobertKohut]

Nice job! It didn't look like you took care of the criss-crossing of the capacitors.

[@oneofthemodels]

No

[@StephenWashburn]

Awesome video!! I have the H400C (same model for canada) and I have that same transformer thats been sitting in a box waiting to be installed, but I found some 'instructables' which put me off with concerns about load standing on the transformer as well as noise introduced due to it being only half wave rectified. But it looks like you didn't have any issues, or concerns, with either, and I trust your work (which I've been able to see and hear on your channel) over 'random dude who wrote an instructable years ago' so it looks like I'll be making a forray into the innards of that amp again! Keep up the good work, and when I invariably screw something up, maybe I'll send it to you to clean up and fix :-)

[@akkudakkupl]

A "1:1" transformer most likely wont have 1:1 winding ratio. Thats because the manufacturer doesn't want to use a larger core to wind the transformer with large gauge wire (beancounters). So they wind the secondary to give a little higher unloaded voltage, that will sag to the nameplate voltage at the nameplate current (due to winding resistance). It's a really common practice. Also Mark Knopfler is a fingerpicker too ;-)

[@douro20]

Isn't that isolation transformer also a bit big?

[@psoup1965]

Hey Brad, realize this is an old video... But QQ for you... On the isolation transformer voltage step up issue... wouldn't it be a better solution to add a pot or some other solution to resist the voltage down? This way you have control of the exact voltage (well close depending on the line voltage) to where you would not have a loss?

[@PhilDavisFilms]

I believe that T2 Transformer is a voltage drop transformer. The other tubes heaters run at the voltages coming into them from mains, 35 or 50v depending on the tube. (I think they're dropped down with dropper resistors) but the 12AU6 needs 12V on the heaters so that T2 drops the voltage down to 12V or thereabouts.

[@TheGuitologist]

It doesn't drop voltage. It's just for isolation. If you add up the series filaments power consumption - 50V + 35V + 12V + whatever the series resistor consumes, that'll equal the full wall voltage.

[@PhilDavisFilms]

Not sure I follow, maybe this is one of those areas I'm still not fully comprehending, but on a 6.3V heater line, I have 6.3V at the start, and it goes through multiple 6V power tubes and multiple 12V preamp tubes on the more common setups (say 6V6 and 12AX7's) but that voltage is 6.3 volts along the entire rail, not dropping as it goes. What am I misunderstanding?

[@PhilDavisFilms]

I may have figured out the answer to my own question, looking at the schematic, the filaments are in series with the line, but in the amps I'm used to seeing, they're paralell with the power. Think that would explain it no?

[@TheGuitologist]

Correct. The filaments here are in series, not parallel.

[@brainndamage]

This is a series string filament configuration, so all tube heaters must share the same current. That one tube probably uses a different heater current so they use the transformer to reflect it to the current the other tubes use. Likely to a higher voltage, lower current.

[@jspinks2388]

Mods man, need some major roll off around 60-75hz drop more couplings, or tinier gong in and still be able to boost bass without fkubbing the cones so bad/rattle.

[@tonycarruthers9556]

Electrical pixies that live in wall sockets .capacitors ,cages for really angry pixies that have the capacity to separate fingers from hands 48.07 on i know why people risk it, pure ear pixiation to the extreme i could lean back on this wall of bliss all day .

[@BoboButYouCanCallMeTom]

Hey brad how do i choose a isolation transformer for my phillips radio? i don't want to be shocked when i touch my mixer. There is also the problem of no one selling isolation transformers in the netherlands but yeah.

[@roscoefoofoo]

Glad you're feeling better!

[@TheGuitologist]

Thanks. Me too.

[@lroy730]

Starting with Kiss references , Nice ! War Machine best Kiss Song !!!\m/!!!

[@Zelleram55]

So did you charge the customer extra for a little Guitologist mojo filled pixie/fingernail dust sprinkled in their amp?

[@bjbeardse]

Should get a small butane torch for the heat shrinking. At least for the Cool Factor! LOL

[@OptOutofGunControl]

I really liked the sound out of that one.

[@LauraSquirrel]

I HATE when I break a nail on my right hand.

[@polaritypictures]

instead of tapping the chassis with your hand, wouldn't it be smarter to just use the probe and take a reading?

[@stirlingarcher2141]

Your videos are great at helping me pass time during slow days at work, good work :-)

[@dustinschilling862]

Hey Brad, would there be a better isolation 1:1 transformer you would recommend for this application. Is the higher output voltage on the secondary indicative of just the Triad brand or is that the case with most iso trannies?

[@TheGuitologist]

It'll be the case with most. The secondary will have a higher voltage with nothing drawing current, but these have seemed a bit too high for me. On the other hand, none of the tubes in these amps are rare, and really that's about all that could happen if you wired it the way it's supposed to go, the tubes would burn faster. But the tradeoff would be the amp would be a tiny bit louder.

[@dustinschilling862]

The Guitologist awesome thanks for the info.

[@FatedSnowfox]

Those Jimmy Page capacitors? That’s his pictogram from Zep 4

[@scottriddle5468]

Man I busted out laughing when you said dam it i broke a f*ckin nail.

[@piersuntersander]

I'm feeling tingles. Glad you're back from the dead!

[@scottriddle5468]

That was i cool video for a newcomer like e thanks man

[@Only1Shadow]

...and that's why everything needs a fuse.

[@silviopimentel7247]

Those amp's have such unique tone 👌

[@brianharris7243]

Useful fuse/tube substitution tip-thanks.

[@SyntheticSajo]

Glad to see you back and hope you well soon.

[@noelharrison902]

can we hear a before and after tone challenge?

[@kosycat1]

5:00 those are awesome they are like tea pots =]

[@68MalKontent]

Hmm. Do you always measure voltages on the secondaries of a transformer without load? You'll always get higher voltage when there's no load. That's basic stuff, Brad ;) And also that transformer seems to have multiple taps, surely you can use them to achieve the 1:1 ratio required (under load....). And to easily remove hotmelt glue the metal needs to be cooled down a lot, with a freeze spray (more expensive) or butane gas (much cheaper).

[@TheGuitologist]

The other taps are for 220v. Yeah, I know on the slightly higher voltage, but I didn't expect it to be that high. Just figured the other way puts less strain on the filaments anyway, and you really don't notice much if any output difference between the two. It's possible I'm wrong on this and the other way would have been fine.