Marshall Major 1967

[AxelKay]

! No longer available

Well, FusionBear got the Major Minor built!  Sounds pretty good to me.

The thread is here on the Gear Page:
http://www.thegearpage.net/board/index.php?threads/the-marshall-major-and-a-tribute-mini-build.1750906/page-4

It's fixed bias with 50k pot I opted for a PT that is 390-0-390 @ 300mA   OT is 120 watt @ 4.3k primary Ultra linear

With respect, Tubenit

@Tubenit Is there a layout for the major MINOR III ? The TAG links are no longer available ☹️

[tubenit]

I am not aware of one specifically.  However,  reply #4 on this thread is a layout for a Marshall Major and it is editable.  You might consider reworking it looking at the Major Minor III which also has  a schematic on that same thread.

http://el34world.com/Forum/index.php?topic=17556.0

The other thing to consider IF a previous layout has disappeared is using the "Wayback Machine" internet search?

With respect, Tubenit

[AxelKay]

No no, all of the forum's links work, but unfortunately I am on my phone for a few days now and cannot open .sch files obviously. I'll check the 100w version of the layout if you say it's there, and give a try to turn it into the 50w minor iii

[2deaf]

A while back I drew up a Major schematic by looking at the gut shots from four different Major's.  One thing I was unable to de-tangle was the large number of wires coming out of the OT and going to those two little exterior circuit boards.  Anybody got any insight into that?

[Ritchie200]

That's what Dawk called the "Christmas tree" - not sure why?  It is just a connection between the OPT and the selector switch (button).  I actually think it allowed the "girls" who assembled the amp to make those connections without flipping the amp.  Ritchie's amps were wired direct 8ohms, bypassing the "tree".  He was not a fan of the silly pull out ohm selector button. 

Jim

[2deaf]

That's what Dawk called the "Christmas tree" - not sure why?  It is just a connection between the OPT and the selector switch (button).  I actually think it allowed the "girls" who assembled the amp to make those connections without flipping the amp.

I've counted no fewer than nine leads going to the Christmas tree.  This reminds me of Hammond's 1600 series where secondary coils are connected externally to get the various impedances. 

[Ritchie200]

Actually there are 13 connections!  Dawk said Ken Brawn told him the women could make (4) 50 watt or (2) 100 watt in the time it would take to build one Major.  Only ~1200 were built (per internut lore...) but I was told less than 1000 of the Major.  There was the Pig (less than 50) and the "200" (less than 30).  With the low volume (so to speak!) of production for the Major, no fancy assembly jigs were ever built.  The women needed help flipping the chassis over after the tranny's were installed (~80 lbs.).  I think the Christmas tree was a cheap workaround to speed production.

Jim

[DummyLoad]

or older sowter transformers with the 4 x 1Ω windings.


--pete

[Ritchie200]

Oh its a single circuit board with a circuit board "cap" to cover the exposed soldered connections. If the gold expanded metal vent screen gets pushed down it can lay on top of this.  Don't ask me how I know....

[2deaf]

Actually there are 13 connections!

Nine coming from the OT and four going to the impedance selector for a total of 13?

Thanks for the picture.  I'll add it to my collection.

[AxelKay]

I am not aware of one specifically.  However,  reply #4 on this thread is a layout for a Marshall Major and it is editable.  You might consider reworking it looking at the Major Minor III which also has  a schematic on that same thread.

http://el34world.com/Forum/index.php?topic=17556.0

The other thing to consider IF a previous layout has disappeared is using the "Wayback Machine" internet search?

With respect, Tubenit

Are all caps rated @ 600v, except for the 500v filters? I may try my luck with the minor iii 
Resistors 1/2w ?
And also.. is the minor iii above 50w or something?

[Ritchie200]

If the Major Minor III is the one Pete (Dummyload) drew up, I don't think he was running those voltages.  I don't have the sch program on this computer so I cant look at it.  If I remember he had figured about 50 watts for that version?  Maybe he can chime in.  He and Ed have built numerous KT88 projects.  Don't be afraid to ask questions.  We beat this amp up pretty good in this thread, that was really neat getting everyone's input. However, I don't think anyone ever built one! (except for someone on another forum who ripped off Tubenit's design and called it his own...)  So, you can be the hero of this 5 year old thread!

Jim

[shooter]

http://el34world.com/Forum/index.php?topic=17548.150
EDIT (reply 187)

I don't have the sch program on this computer

the 3rd file down is PDF, but I know, after two, things get a little fuzzy 
IMHO there are 3 too many input jacks 

[AxelKay]

If the Major Minor III is the one Pete (Dummyload) drew up, I don't think he was running those voltages.  I don't have the sch program on this computer so I cant look at it.  If I remember he had figured about 50 watts for that version?  Maybe he can chime in.  He and Ed have built numerous KT88 projects.  Don't be afraid to ask questions.  We beat this amp up pretty good in this thread, that was really neat getting everyone's input. However, I don't think anyone ever built one! (except for someone on another forum who ripped off Tubenit's design and called it his own...)  So, you can be the hero of this 5 year old thread!

Jim

Oh yes.. I AM building this! By the way, that other guy from the ampgarage forum built the 100w, not the mini iii which is indeed 50w cathode bias. I'm on my phone the past few days and cannot open sch files either. The pdf doesn't state resistors' wattage (apart from the obvious 1kw's) or cap voltage..

[shooter]

If it's mine
ALL plate R's are 1w, all other R's (beside important big PA ones) are 1/2w
all coupling caps are 400-600vdc
all PS caps with + sign need to be bigger than the vdc they deal with
all odd caps in-circuit with + signs can be guessed at pretty easy

bigger is better 

[2deaf]

EDIT (reply 187)

I didn't get very far with reply #187, but I scrolled on down to reply #194 by Dummyload.  Here he talks about a Heyboer replacement OT for a Major with five secondary sections.  I can see nine leads coming out of the secondary side of an original Major OT and there could easily be a tenth that I can't see.  Or it may have an internal connection so that it has five sections but only nine wires.   

[AxelKay]

bigger is better 

... that's what she said! ... and I agree xD

[shooter]

with reply #187

it's actually #184 where the pdf is, but I'm dyslexic so the "4" got replaced by the "7"
from the thread title 

[Ritchie200]

IMHO there are 3 too many input jacks 

My dear baaay, THAAAT is wot is knawn as trrradition!

Jim

[DummyLoad]

That's what Dawk called the "Christmas tree" - not sure why?  It is just a connection between the OPT and the selector switch (button).  I actually think it allowed the "girls" who assembled the amp to make those connections without flipping the amp.

I've counted no fewer than nine leads going to the Christmas tree.  This reminds me of Hammond's 1600 series where secondary coils are connected externally to get the various impedances.

based on the heyboer major clone transformer information i posted in 2017 (reply #192), the OT is stated to have 5 secondaries & two primary sections - so one would assume there would be AT LEAST 10 wires to the "x-mas tree".

--pete

[2deaf]

it's actually #184 where the pdf is, but I'm dyslexic so the "4" got replaced by the "7"

Maybe not.  I said reply #194 and now it's reply #192.  Of course, I could be dyslexic, also.  Reply #160 is still reply #160.

[Ritchie200]

Ok, dont laugh....  too hard....


I've been here for what....15? 20? years?  On this board I have posted over 3000 (mostly useless) times.  On these long threads I see people referencing reply #200 or posting #100 and I'm thinking, who the hell has time to count these posts!!!!  Get a life man!!!! 


sigh....


I just NOW noticed the reply count...


Oh jeez, I just need to dig the hole now, fall in, and wait for the inevitable.


Jim

[AxelKay]

Ha! Talking about dyslexia! I've mentioned about having a hard time turning layouts into schematics and vice versa!!! Takes me x4 times longer than the average person! But if as you said the major minor and the minor iii schematics are 101% correct and accurate, it's way more than worth the time dedicating on a layout and complete build!

[shooter]

one of the fun things in the Navy was the "telephone game", by the time the phrase came back around I was married to my Mom 

I just seem Minor III pdf n went with it n messed up 



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Re: Marshall Major 1967

« Reply #184 on: January 08, 2015, 04:50:12 pm »


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current and corrected schematics in .SCH format can be found in the link below:


http://el34world.com/Forum/index.php?topic=17556.0


thanks jazbo8 for the errata. :-) 


PDF version attached to this message.


Major_Major is 200 Watt Fixed Bias
Major_Minor is 100 Watt Fixed Bias
Major_Minor_III is 50 Watt Cathode Bias.


--pete


* Major_Major_Schema.pdf (58.68 kB - downloaded 201 times.)
* Major_Minor_Schema.pdf (56.15 kB - downloaded 242 times.)
* Major_Minor_III_Schema.pdf (52.2 kB - downloaded 240 times.)

[PRR]

> dyslexia! ...hard time turning layouts into schematics and vice versa!!! Takes me x4 times longer than the average person!

The "average person", my neighbor, your neighbor, could never do that. Jimmi next door is a good mechanic but can't draw the fuel gauge of a Hudson (2 wires!). So you are already in the 1%.