74 Marshall 1959 Restoration. ELIMINATING MAINS HUM!! 

I don't know why, but i watch a lot of amp repair videos. They hold my attention well, especially if it is a classic amp. This channel, plus Uncle Doug and one called Psonic Audio. I will do pickup swaps, but I am still not game to get inside my amps in a big way. I do not trust my shaky hands and 52 year old eyes that need replacing. The other thing is getting the parts is a pain in the butt in NZ. Everything has to be imported pretty much.

I’d leave the exterior in that awesome used looking condition!!

Amazing. I never heard of a failed choke. They seem so robust compared to the other power supply components.

Very interesting, thanks for sharing your knowledge Jason. Love these Marshall repairs.

I always look forward to your Marshall Vids.

Nice detective work, Jason! There are so many sources of hum, and its a pain to track it down. Its really impressive watching someone who knows their stuff figure these kinds of issues out.

Yep, me too. Never worked on an amp in my life but I love these videos. Guitar setups too…lol

Jason, that was awesome! I hope you can continue to do these in the future...

Fantastic video Thanks for sharing Jason!!!

Wow, the playing at the end sounds so freakin good !

Still working on the Gunslinger build (High Gain marshall-y circuit) and your videos are super helpful and informative, my wife always catches me watching these at all hours! Cheers from New England, USA. -Dave from Iron Age Amps

Can't thank you enough for the information you share

This video is a life saver! Was getting 120hz hum and have a ppmiv in my plexi clone as well and sure enough both sides of the choke are measuring about 2ish volts AC. Would have never guessed!

Very cool Info

This was helpful. I have 100Hz hum in one of my new amps. And I was suspecting the choke to be: a) wired wrong, b) part defect. Becasuse no input, all at 0 and there was still huge hum. I will get back to this amp and check it today!

Jimi Hendrix is BACK!!! That sounds good!!!

I would love to see an episode on getting the hum out of an AC-30.

That Marshall has a great patina 🙂it’s a shame that Luke turned the amp on and didn’t try to reform the capacitors first

Its just a coil Jason. It either goes shorted or open. I'd say it shorted in your case, thus not providing the filtering effect but still allowing the current to pass. Nice troubleshooting tip!

I wished I had such a great tech. My amp still hums...

Man this thing sounds FANTASTIC... it's a beast!

Im not a strat guy, but man, that looks an absoluty beauty…

Great troubleshooting! Did you put all four output tubes back in or just two as it arrived? Did you keep the PPIMV? just how cranked where your volumes on the recording? sounds great!! learned a lot again as usual Thank you again for another great lesson!!

Par Excellence!

👍👍

Pretty sure I used to own this amp about 8 years ago. I had it shipped from Chicago Music Exchange to Central Coast NSW and did a straight swap for a 82 2203 with a guy from Wollongong. Not sure what I was thinking but I was frustrated that I couldn’t get any overdrive out of it without going deaf. I use an attenuator with my 70 Superbass and 71 1987 these days and would love to have this old warhorse back. Edit : just watched the video and obviously not my old amp but jeez it looks like it.

Sounds great with that strat. Old Aussie transformers are still cool. Ever work on old Australian/NZ gear?

Good Video. And good Strat soud. Kinman Pick-up's ?

I tried my best to keep up, dont understnd half of it but a very interesting run through of everything and now sounds amazing! With regard to ripple, what effect does that have on an amp if it were increased or decreased? Is it less noise floor or something along those lines?

Great result and playing mate. Just one minor corrective comment re your suspicion for the reason why the choke lost its inductance - highly unlikely due to some demagnetisation efect. Much more likely a shorted turn or few, possibly insulation of the enamel wire damage. Great use of AC voltmeter to probe for that kind of a fault, I usually use the CRO on ac coupling and x10 probe. Cheers from Sydney.

Hi Jason. Great channel! Believe it or not those PCB mount pots are original in the early first gen ST1 board amps! Ive seen the same makes consistently in amps of that era in the amps Ive been in. Not saying that there aren't plenty of amps out there with replaced pots but the ones in your customers amp look to be the same as what Ive encountered.

These old early 70's Marshalls are supposed to be amongst some of the good ones, I think Angus Young from AC/DC has a few early 70's Marshall Super Leads in his collection, think he also has some Marshall JTM45s as well.

Hello Jason.

How did the tolex get so torn up lol

just wow lol

Jason, I just love bringing these things back up to snuff! The components, like electrolytics now-a-days are FAR superior to the old ones and should ALL be replaced in my opinion. Likewise, all of the carbon comps which drift all over the place over time and I've measured off by 50, 75, 100, 200%!! :O No wonder these things dont sound consistent! I've never had a bad choke situation either, so this is a first! Wonder what the hell happened and as original Marshall choke?!? One thing to point out is while working on old amps...old Marshalls, Blackface Fenders, old Laney's....I've had issues with amps on the bench and scratching my head as to what the fuck was wrong. In the end, in more than one case, it was actually the DIODES! So, I recommend replacing them also in old amps and just get ahead of the curve as without it and you fix whatever issue you have...recap electrolytics, etc....you're sitting on a timebomb and it's only a matter of time when the diode will take a shit! Anyway, had it on multiple amps and just relaying the issue(s) I've experience in the last 12 years in the business. When these things have all good components....goddamn it, they sound good and that classic tone! I seen this amp and the flat toggle switches and setup and said to myself....looks like an early 70s...yep!

Hey Jason,watching this got me wondering about an issue I am having…..I have my amp(Friedman) connected to a load box(Fractal X-Load),then the line out of the Load goes to a Marshall 9005 power amp,then to a cab….My issue is that when I turn the power amp all the way down,I can hear my guitar coming thru my studio monitors,and they are in no way connected…..the amp/load box is somehow “transmitting”my signal and it’s being picked up by my monitors(Yamaha HS8’s)…….It’s not loud,but it’s there…have you ever heard of this?…..I know it sounds crazy,but it’s happening…

I would have returned it to original. Including new electrolytic capacitors of course.

Let me guess; the owner was told it was 'stock' when they brought it? 😉

Puoi spiegarmi perché ha due valvole diverse e con due può suonare lo stesso

leave that look , its awesome, i'm surprised people dont actually pay for their amps to get "relic'd" like they do guitars !