JTM 45/100 67 EL34

Detailed assembly steps separated into threads.

Moderator: VelvetGeorge

Homebelly
Senior Member
Posts: 101
Joined: Tue Mar 31, 2009 5:52 pm
Just the numbers in order: 7
Location: Aotearoa New Zealand

Re: Help with my JTM100 1203-80 layout

Post by Homebelly » Tue Mar 20, 2012 5:27 pm

Okay..
How about this..?
Image
Rectifier and filter board-2 by Homebelly

I've been trying to work it all out using the schems linked to above.
I'm still not sure about where #3 and #4 goes :shrug:
Some of my toonz. http://soundcloud.com/sets" onclick="window.open(this.href);return false;
My stuff; two strats, one with Van Zants, the other with Fralins. A Jazz bass. One PRS McCathy gold top.

User avatar
Kevin
Senior Member
Posts: 534
Joined: Thu Mar 02, 2006 5:58 pm
Just the numbers in order: 7
Location: Toronto
Contact:

Re: Help with my JTM100 1203-80 layout

Post by Kevin » Tue Mar 20, 2012 8:03 pm

Hey Charlie,

Green wire (heater center-tap) should go to ground, not between the mains caps.

Yes, that orange "Choke?" wire should go to the choke. Another wire from this point should go to the OT.

3 should go to a screen grid resistor on a power tube socket (they are all connected).

4 should go on the bottom end (pot side) of the voltage dropping resistor for V3/PI (big one beside the bias supply).

Are you going with the dual-rectifier setup? My recommendation is to wire it up as a single primary with centre-tap, leaving the bottom diamond in place for looks. Depends what tones you're after... Maybe Roe and Neil will chime in on this point.

Are you going with Larry grounding? If so, the grounds have to be broken up.
Last edited by Kevin on Tue Mar 20, 2012 8:14 pm, edited 1 time in total.

Homebelly
Senior Member
Posts: 101
Joined: Tue Mar 31, 2009 5:52 pm
Just the numbers in order: 7
Location: Aotearoa New Zealand

Re: Help with my JTM100 1203-80 layout

Post by Homebelly » Tue Mar 20, 2012 8:12 pm

Kevin wrote:Hey Charlie,

Green wire (heater center-tap) should go to ground, not between the mains caps.

Yes, that orange "Choke?" wire should go to the choke. Another wire from this point should go to the OT.

Are you going with Larry grounding?
Hi Kevin.. good to see you up in my build thread :rock:
I got a thread running on the mastran forum and Brian just posted.. these are his tips..
Image
Rectifier and filter board.3 by Homebelly

And yes.. i'll be going with Larry's grounding scheme.
I'll work up a drawing for that after i have this all figured out.
Some of my toonz. http://soundcloud.com/sets" onclick="window.open(this.href);return false;
My stuff; two strats, one with Van Zants, the other with Fralins. A Jazz bass. One PRS McCathy gold top.

User avatar
Kevin
Senior Member
Posts: 534
Joined: Thu Mar 02, 2006 5:58 pm
Just the numbers in order: 7
Location: Toronto
Contact:

Re: Help with my JTM100 1203-80 layout

Post by Kevin » Tue Mar 20, 2012 8:15 pm

Edited my post after your response.

Homebelly
Senior Member
Posts: 101
Joined: Tue Mar 31, 2009 5:52 pm
Just the numbers in order: 7
Location: Aotearoa New Zealand

Re: Help with my JTM100 1203-80 layout

Post by Homebelly » Tue Mar 20, 2012 8:27 pm

Kevin wrote:Edited my post after your response.
Cheers Kevin.. :champ: :worthy:

I'm planning on using the dual rec for the actual build, then maybe try the amp with a single rec later down the line.

I must also add that i am loving the detective work involved in this, i must have every picture of every dual rec Marshall that is available on the interwebz on my hard drive, along with as many schem's as i can find. Its all equal parts revealing and confusing :scratch:
Some of my toonz. http://soundcloud.com/sets" onclick="window.open(this.href);return false;
My stuff; two strats, one with Van Zants, the other with Fralins. A Jazz bass. One PRS McCathy gold top.

Roe
Senior Member
Posts: 5054
Joined: Thu Apr 13, 2006 1:36 pm
Just the numbers in order: 7
Location: Drontheim. Norwegen
Contact:

Re: Help with my JTM100 1203-80 layout

Post by Roe » Wed Mar 21, 2012 8:19 am

Homebelly wrote:
Kevin wrote:Hey Charlie,

Green wire (heater center-tap) should go to ground, not between the mains caps.

Yes, that orange "Choke?" wire should go to the choke. Another wire from this point should go to the OT.

Are you going with Larry grounding?
Hi Kevin.. good to see you up in my build thread :rock:
I got a thread running on the mastran forum and Brian just posted.. these are his tips..
Image
Rectifier and filter board.3 by Homebelly

And yes.. i'll be going with Larry's grounding scheme.
I'll work up a drawing for that after i have this all figured out.
Its starting to look good - and yes the larry grounding is worth looking into
http://www.myspace.com/20bonesband" onclick="window.open(this.href);return false;
http://www.myspace.com/prostitutes" onclick="window.open(this.href);return false;
Super 100 amps: 1202-119 & 1202-84
JTM45 RS OT JTM50 JMP50 1959/2203/34/39

emmjaydubya
Senior Member
Posts: 376
Joined: Tue Mar 01, 2011 6:51 pm
Just the numbers in order: 7
Location: Austin

Re: Help with my JTM100 1203-80 layout

Post by emmjaydubya » Wed Mar 21, 2012 7:06 pm

Wow fantastic thread, thanks guys!

Homebelly
Senior Member
Posts: 101
Joined: Tue Mar 31, 2009 5:52 pm
Just the numbers in order: 7
Location: Aotearoa New Zealand

Re: Help with my JTM100 1203-80 layout

Post by Homebelly » Thu Mar 22, 2012 3:05 am

emmjaydubya wrote:Wow fantastic thread, thanks guys!
You welcome..
Its nice to be getting all of the great feed back from the different builders up in the joint, and also finally be able to give something back after my three years of being a member, and my previous year or so of being a lurker and sucking up all of the great knowledge available here. :toast:

I should be able to post a couple more sketches early or mid next week.
Some of my toonz. http://soundcloud.com/sets" onclick="window.open(this.href);return false;
My stuff; two strats, one with Van Zants, the other with Fralins. A Jazz bass. One PRS McCathy gold top.

Homebelly
Senior Member
Posts: 101
Joined: Tue Mar 31, 2009 5:52 pm
Just the numbers in order: 7
Location: Aotearoa New Zealand

Re: Help with my JTM100 1203-80 layout

Post by Homebelly » Thu Mar 22, 2012 7:42 pm

Kevin wrote:
3 should go to a screen grid resistor on a power tube socket (they are all connected).

4 should go on the bottom end (pot side) of the voltage dropping resistor for V3/PI (big one beside the bias supply).
How is this?
Image
Final filter cap hookup by Homebelly, on Flickr
Some of my toonz. http://soundcloud.com/sets" onclick="window.open(this.href);return false;
My stuff; two strats, one with Van Zants, the other with Fralins. A Jazz bass. One PRS McCathy gold top.

Homebelly
Senior Member
Posts: 101
Joined: Tue Mar 31, 2009 5:52 pm
Just the numbers in order: 7
Location: Aotearoa New Zealand

Re: Help with my JTM100 1203-80 layout

Post by Homebelly » Fri Mar 23, 2012 12:18 am

Okay..
And here is the out-put transformer, can some one let me know if this is all good?
I think it's pretty straightforward, but just want confirmation.
Image
Out-Put transformer impedence and speakers by Homebelly, on Flickr

Cheers. :toast:
Last edited by Homebelly on Fri Mar 23, 2012 2:25 am, edited 1 time in total.
Some of my toonz. http://soundcloud.com/sets" onclick="window.open(this.href);return false;
My stuff; two strats, one with Van Zants, the other with Fralins. A Jazz bass. One PRS McCathy gold top.

Homebelly
Senior Member
Posts: 101
Joined: Tue Mar 31, 2009 5:52 pm
Just the numbers in order: 7
Location: Aotearoa New Zealand

Re: Help with my JTM100 1203-80 layout

Post by Homebelly » Fri Mar 23, 2012 2:19 am

And one more.
This one showing the secondaries, the choke and the Grid stoppers.
Image
Out-Put transformer and choke by Homebelly

Once again.. feed back welcomed.
But again, i think this is pretty straight forward.
Some of my toonz. http://soundcloud.com/sets" onclick="window.open(this.href);return false;
My stuff; two strats, one with Van Zants, the other with Fralins. A Jazz bass. One PRS McCathy gold top.

User avatar
neikeel
Senior Member
Posts: 7231
Joined: Tue Dec 06, 2005 8:31 am
Location: Suffolk, England

Re: Help with my JTM100 1203-80 layout

Post by neikeel » Fri Mar 23, 2012 3:46 am

Hi, back again!
Yes looks fine to me (assuming all your colours are correct for the trannies you are using!)
Neil

shakti
Senior Member
Posts: 2053
Joined: Tue Apr 05, 2005 9:06 am
Just the numbers in order: 7
Location: Ramnes, Norway

Re: Help with my JTM100 1203-80 layout

Post by shakti » Fri Mar 23, 2012 8:05 am

Check your screens and PI filtering layout again...it's messed up.
JTM45 RS OT, 1973 18W, JTM45/100, JTM50, JMP50 1986, JMP100 "West Coast", AC15, AC30, BF Super Reverb, Boogie Mk 1, Hiwatt CP103, DR103

User avatar
neikeel
Senior Member
Posts: 7231
Joined: Tue Dec 06, 2005 8:31 am
Location: Suffolk, England

Re: Help with my JTM100 1203-80 layout

Post by neikeel » Fri Mar 23, 2012 12:30 pm

Ah - I only checked the OT diagram bit!

You need to take the HT feed (after the choke) to the turret where the wire is hooked up now (one end of the 8k2 dropper) and take a yellow wire from that turret to your screens.

The other end of the 8k2 dropper should have that short red feed wire (to teh PI plates) which should then be hooked up to the PI filter cap and then on through the bus wires into the preamp.
Neil

Homebelly
Senior Member
Posts: 101
Joined: Tue Mar 31, 2009 5:52 pm
Just the numbers in order: 7
Location: Aotearoa New Zealand

Re: Help with my JTM100 1203-80 layout

Post by Homebelly » Fri Mar 23, 2012 11:25 pm

I'm not in good shape today i must admit. :stars:
Nasty migraine, so i'm not running on all cylinders.
Probably not the best state of mind to be in while looking at this sort of stuff, but can some one confirm I have this diagram correct..
Homebelly wrote:
Kevin wrote:
3 should go to a screen grid resistor on a power tube socket (they are all connected).

4 should go on the bottom end (pot side) of the voltage dropping resistor for V3/PI (big one beside the bias supply).
How is this?
Image
Final filter cap hookup by Homebelly, on Flickr
Some of my toonz. http://soundcloud.com/sets" onclick="window.open(this.href);return false;
My stuff; two strats, one with Van Zants, the other with Fralins. A Jazz bass. One PRS McCathy gold top.

Post Reply