NOAFCD

[Greg_L]

New Old Amp From Canada Day! 1976 Marshall JMP 2203!

In FAWN TOLEX!

This one was brokered by @WhiskeyJack. Long story not really shortened at all...WJ knows a guy, we'll call him "L", that found this amp in Canuckistan while a widow was clearing out her dead husband's storage locker. Something like that. L bought it just because what it is but it didn't work. He's a flipper type guy. WJ got with me about how they can fix it. I got a few pics of the guts and said something like "yall need to send it to me, I'll fix it and send it back" because I really wanted to see this thing and this amp deserves to work. They are rare as hen's teeth! But in my devious mind my idea was I'd get the amp down here, the repair would be too much for L to deal with, and I'd buy it from L for what he paid. Also, L was getting some heat from his wife for the impulse buy so I thought he'd be pretty motivated to just be rid of it. Win/win!

But before we even got to that point my conscious started working on me and I made an offer before he shipped it to me for repair. This is pretty much where WJ slowly backs out of the whole scenario. Lol. I didn't want to "trick" L into selling it to me and WJ didn't wanna be in the middle of negotiations between two of his friends. I made what I thought was a fair offer compared to what he paid but it was still insanely laughably low for what the amp actually is. He accepted and we made plans to ship. I needed more pics first though. And when I got them...whoa. I took my offer off the table. That amp was pretty thrashed. I'll show my concerns in the pics. So now WJ is out of the conversation and I'm dealing directly with L via email. I explained my concerns, explained my experience with these amps, and made a much lower offer that he declined...but he still would have made some money. No big deal, it wasn't meant to be, I wished him luck and if he changed his mind I'd pay him that night. We cyber high-fived and that was that. A few minutes later he accepted my offer but added that I pay shipping. No problem. He shipped it that night....even before I paid him. Pretty cool. Amp on the way!

Here's what it looked like as he got it....

Some shitbag, probably some stupid fucking zit-faced heavy metal dork from yesteryear, added a cooling fan to the amp at some point.


No idea what's happening here.


These are some of the red flags I saw in the second round of pics. Some serious, some not so much.


I was actually partially wrong on this one. Those white plastic shafts and missing knobs screamed "replaced" to me, but after opening the amp up, all the pots have those plastic shafts and matching date codes that coincide with the age of the amp. Maybe that's a Canadian market thing? Don't know, but they do actually seem to be original....or at least from the same time period. Whatever the case they've seemingly been with the amp since it was new.


Lots of crust on these original filter caps.




These are the gut shots I got at first. Some scary stuff happening in here.






Again, I think I was wrong about the pots. But the heart of the circuit board, the stuff where guitar signal actually passes through, looks amazing and very original. That's where the tone is, and I liked what I saw.


So about 10 days later I got the amp. And here's my repair stuff.

Replaced every one of these dudes. Six of them. Original filter caps...28th week of 1975. They actually still measure okay! But they are very light in weight meaning they're pretty dried out inside. They seem fine sitting there doing nothing but I wouldn't trust them in live action. Replaced.



Next...why does the amp not work? First thing...repair the power switch. It's fucked. I rebuilt and rewired it. But that was not enough. It's still intermittent even as I type this. New switch is on the way. It will turn on now though. It just might not stay on.


This is where things really failed on the amp. There is a threeway of shit happening that are all related.
1) The speaker output impedance selector is missing a piece. The amp sees no load. We all know that's very bad for tube amps.


2) Dead power tube.


3) Nuked screen resistor.


Some chicken-egg scenario happened that killed a tube and popped the screen resistor, or the resistor failed and killed the tube, whatever. I think the impedance selector jumper fell out, as they tend to do, the amp went into a no-load condition, the tubes went nuclear, and fried the screen resistors. In my mind that's how the order of failures occurred. Other screen resistors were also heated and blistered so I think I'm right.




They all got replaced.


So that was actual failure stuff. The rest was just getting it back to original spec with correct parts.

Like these dropping resistors. Don't know who the fuck did this, but it's bad. They are piggybacked 1/2 watts where there they should actually be at least 2 watt resistors. The resistance value is correct, the wattage handling is not, hence the burn and discoloration. There were four of these rig-jobs throughout the B+ rail. All gotta go.




The correct stuff...


Looks like factory fresh


So now it's all fixed. New filter caps, new bias caps, new screen resistors, new dropping resistors, cleaned up and biased up and (not pictured) I did remove and repair the stupid wire nuts at the fuse holder. So dumb.


And this is after cleaning the exterior chassis lol. This thing was cruddy.


Alive....


Made for Canada. How do I know? Well the "CSA" on the build tag says so. Nov 5, 1976. I'm not gonna make a long post longer by going into the weird specifics but this thing has some unique features that I'm pretty sure have to do with it being made for Canada. But it's good for the USA too!



And this is how she looks.




I have not and will not clean or repair the cosmetics. The head box has obvious holes cut into it and I'm just gonna live with it. It's still a super rare and very very cool vintage Marshall amp...and I got it for a steal. Look up prices on Fawn Marshalls on Reverb. My total investment, including parts and shipping...$1530. Most importantly to me, the bits that really matter, the making sound parts, are all there, original, and working as they should. It even still has the original preamp tubes.

And most importantly...it sounds fucking unbelievable. For those that know....if you can imagine the perfect 70s Marshall tone, this thing does it. This thing is that sound. It's so bad ass. Tones coming soon. Let me get this thing settled in.

[JD01]

That's really cool.

You've done a fair few of these now - are you getting more used to sort of looking at it and mentally breaking the circuit down into modular sections and thinking "That's fine, that's fine, ah, that's fucked, sort that out" without having to check against schematics? Just having a good idea of what each section of the circuit does and how they interact with eachother?

[Lt. Bob]

[Greg_L]

That's really cool.

You've done a fair few of these now - are you getting more used to sort of looking at it and mentally breaking the circuit down into modular sections and thinking "That's fine, that's fine, ah, that's fucked, sort that out" without having to check against schematics? Just having a good idea of what each section of the circuit does and how they interact with eachother?

Yes totally. Especially with these old Marshalls. I mostly had this one figured out just from the pics before it even got to me. I know what to look for, what the component values should be and where, and what voltages to expect at certain spots, etc. I did this whole amp without the schematic because I've already been inside so many 2203s and 2204s. But I did consult the schematic later just to be sure. The main thing I was looking for is how a Canadian amp differs from the US and UK versions. Turns out...it doesn't. The power transformer is a little different in that it lays down like an older Plexi and it has super high voltage. That's a little unusual compared to US and UK versions from this time period which had stand up transformers and slightly lower voltages. But the rest of the components are all the same and it's built sort of like a hybrid. It wants 120v AC like a US version, but it's set up to run EL34s like a UK version. Best of both worlds!

Just a few years later as these amps transitioned to the JCM 800 name, the Canadian versions got a lot different and weirder and no one really wants those. But this one was well before all that. It's pretty much exactly what you'd want a 70s JMP 2203 to be! I think most Marshall geeks consider the 77-78 2203s to be the best ones. That seemed to be the sweet spot where Marshall found it's way with master volume amps and the components they had on hand were the best for the amps. This one is a 76 but it's right there in that sweet spot IMO.

[musicturtle]

What an acquistion! Cool that you can do this work and do it well. Always impressive to see how quick and tidy you put these things together.

Guess you can call this one the "Marsh"

[JD01]

Well done, that's excellent.
Is the next stage trying "design in" tone changes that you might want?

[Greg_L]

What an acquistion! Cool that you can do this work and do it well. Always impressive to see how quick and tidy you put these things together.

Guess you can call this one the "Marsh"

Well done, that's excellent.
Is the next stage trying "design in" tone changes that you might want?

No no this thing is staying stock.

[JD01]

What an acquistion! Cool that you can do this work and do it well. Always impressive to see how quick and tidy you put these things together.

Guess you can call this one the "Marsh"

Well done, that's excellent.
Is the next stage trying "design in" tone changes that you might want?

No no this thing is staying stock.

Oh, I realise that with this one. I meant more generally, you think you're gonna design the sound you want out of an amp?

[Armistice]

Awesome work Greg!

[Greg_L]

Oh, I realise that with this one. I meant more generally, you think you're gonna design the sound you want out of an amp?

I doubt it. I mean, I get what you're saying, but IMO the perfect amps already exist...like this one. How could I possibly improve on these things? The sound I want is these amps. Lol. All they have to do is work properly and that's my sound. If I was to "design" my own circuit it would look an awful lot like a 2203/2204. I might bump the gain up a hair. Maybe.

[Greg_L]

Awesome work Greg!

[rayc]

Excellent all the way through. reviving the desecrated !
I do think you should find a Marshall logo "a" and make the amp Marsha o.

[Greg_L]

Excellent all the way through. reviving the desecrated !
I do think you should find a Marshall logo "a" and make the amp Marsha o.

I do have another 9 inch logo just sitting around somewhere. Maybe I'll pop it on.

[Tadpui]

Hell yea man, that's a really cool looking (and sounding, I imagine) amp. Nice job with the restoration! I've never seen that style before.

I love my mid 80s 2204 but it's a little finicky and fizzy sounding to me. I've long wanted a 70s JMP like that, I think that's the quintessential Marshall sound that I want. Someday. After I financially recover from this whole building a house thing.

[Armistice]

After I financially recover from this whole building a house thing.

Ha ha - that'll only take you a decade...

[Greg_L]

Hell yea man, that's a really cool looking (and sounding, I imagine) amp. Nice job with the restoration! I've never seen that style before.

I love my mid 80s 2204 but it's a little finicky and fizzy sounding to me. I've long wanted a 70s JMP like that, I think that's the quintessential Marshall sound that I want. Someday. After I financially recover from this whole building a house thing.

Ha but think of how loud you'll be able to be with all that land!

You might just need a proper full-sized cab for it. While those 4x10 cabs are cool and unique, I don't think they really let a Marshall be what it is. I'm not crazy about my Marshalls through 10" speakers either.

Also.....

2204prem1.jpg

See that thing circled in red? That's your preamp volume pot. It's got a small 1nf capacitor across it called a "bright cap" occupying the C5 spot on your circuit board. Warm up the soldering iron, remove that cap, and your fizz will probably be gone. Actually you only need to lift one leg of it but leave it in place so it's still there but not connected. Very common thing to do for people that find their Marshalls to be too fizzy. It's kind of like a treble bleed on a guitar so as you roll the volume down it still maintains it's chime and clarity. If removed, the amp should thicken and darken up at lower gain settings. But it also might lose some of it's kerrrang at lower settings. At higher gain settings it's moot. That cap stops doing it's thing at around 7-ish on the gain dial. It's like it's not even there at full roar.

[Greg_L]

So finally gave this thing a proper run through last night at band practice.

1) It sounds fantastic. It worked flawlessly. No fires, no smoke, no damage. Passed the test.

2) It's nutty loud. It's got that thing where it's bedroom volume and then with one micro-twitch of the volume knob it's blowing the windows out. That's about 1-2 on the master volume. And then you go further and space rips open and wormholes appear and you are not human anymore. That's about 6-7. After that it's so loud you can't even perceive any changes. It's like a rock and roll jet landing in your living room. It's savage. I think I'm gonna have to put a different volume pot in it just to make it's range more usable for live situations.

3) I'm gonna have to shield the input. I'm getting mexican radio stations at idle. I'm not getting that situation here at home, but out in the city where buildings are old and interference noise is rampant it can be a problem. Our practice room is about as shitty as it gets for dirty power and stray noise so if I can get it quiet in there it'll be quiet anywhere. As it stands in it's original state the input from the jack to the grid of V1a is just wire. No shielding and the grid stopper is in a weird spot. I'll remove this and use proper shielded wire in it's place. I'll add the grid stopper directly to the tube socket. That should handle the problem without affecting anything else.

4) Did I mention how loud it is?

[JD01]

Have you ever done a relatively scientific loudness test with your amps? Like put a dB meter 1m from the front of the cab, put a reamped piece through each of them cranked to see what happens?

[Greg_L]

Have you ever done a relatively scientific loudness test with your amps? Like put a dB meter 1m from the front of the cab, put a reamped piece through each of them cranked to see what happens?

No. For one I don't have a db meter. It's like...is this lava hotter than this lava? Probably a little but it's meaningless because it's all lava and will incinerate anything in it's path. Same with 50+ watt amps. They're all loud as fuck. I don't need to be more scientific than that. Everyone raves about how loud Plexis are, and they are loud as shit, but to me the 2203s punch harder. A 2203 seems louder to me than a Plexi/1959.

I have scoped the output and measured actual wattage. It's good to see the waveform and it tells you the general health and efficiency. These things kick out well over their rated 100 watts.

[JD01]

I used the shitty phone dB meter. In my office on 1W mode my HK nudges 100db.