Anderton '64 reissue JTM145 - any info?

[MHProd]

I own a JTM1. Great little amp!!

Let me get my HD camera and I'll post pics.

I'll try to show as many values as possible. Unfortunately, I can not draw a layout or schematics but would LOVE to have one so I build a proper P2P version with NOS parts.

[Matec]

MHProd

This is not a problem.

The complete scheme, and 100% checked is very close, and it will be easy to draw with their photos.

The P2P layout can be done by me or someone else, there are guys who can do that very well.

We're just waiting for these photos. I and the entire World.

Write when you're ready to take the photos. Then I can tell where I need specific images.

I'm waiting.

Matec

[build]

Hi there,

I have a JTM145 head. What would you like to know?

[jazzkramer]

YESS YESS YESSS build !!! The best sounding 1 watter!!!

Let's wait for the experts here

Thanks in advance for your help!

jazzkramer.

[jazbo8]

Hi there,

I have a JTM145 head. What would you like to know?

A lot about the design is already known, we just need close-up photos of the PCB for confirmation if you would like to contribut to the knowledge base.

[Littlewyan]

Both sides of the board please and especially the tone circuit board.

[build]

Here you go.

I will do the tone daughter board later.

[Littlewyan]

Brilliant! Could you please read off the values of the electrolytic caps and any caps we cant see the value of in the pics? Sorry if I'm asking a lot but the biggest issue we have is reading the caps that have their values on the side.

[build]

BOOOOM!

C1 1uF 100v
C2 4700uF 25v (next to D5/D6)
C3 33uF 500v
C5 33uF 500v
C6 1uf 100v
C8 471k 500v
C9 222
C12 3.3uF 100v
C14 33uF 500v
C19 101 1kv
C20 471
C24 1uF (next to R30)
C25 220uF 500v (next to R33)

[build]

I read some people have modified the Marshall C5 rectifier to switch between V1 Valve' (For Maximum SAG) or 'V2 Valve' Operation or the original solid state.

Does anyone know how we could do this to the JTM145 circuit?

[Matec]

Now it was!

I just want to put some small corrections to this list

C1 1uF 100v
C3 33uF 500v
C2 4700uF 25v (next to D5 / D6)
C5 33uF 500v
C6 1uf 100v
C9 222
C8 471k 500v
C12 3.3uF 100v
C14 33uF 500v
C19 100pF 1kV
C20 470pF
C24 1uF (next to R30)
C25 220uF 35v (next to R33)

Yeessss!!!

[Littlewyan]

Very interesting values. I would have thought that using .0022uF Capacitor in the RC Filter between the two 12AU7 Anodes would make the amp sound dull. I'll have to try this and see. Perhaps they compensated by using the 1uF Capacitors for the 12AU7 Cathodes and the Cathodyne Cathode.

Am also unsure about C8 and C12, can't see where these would go?

O yer and thanks a lot build for these photos. Without you we wouldn't be able to get this far.

[jazzkramer]

Ok guys, so, today is the day!! PLEASE DO NOT CONFUND, THIS IS
The JTM1 ONLY (NOT THE 145!!) BOARDS:[/img]

(so let's concentrate on the 145 much more interesting!!!)

Input board is so small I can not take a pic, but the only thing is:

in the jack tip are connected: one ceramic condenser (don't know how to read the value, it says 4 7 all underscored) and a resistor:Brown, Black,Black, "yellow"(or gold?), brown. (why 5 colors? I knew abot only 4!!)

the other side of the resistor and condenser are both to the mass, so I think they are in parallel with the input jack.

Waiting for the JTM145 much more interesting!!

And let's look the tone stack is "ready" for mods

I'm here for any help or questions

Now the experts will do the thing I hope!!

Will we be able to modify a JTM1 to JTM145 (my friend, the owner asking!! )
Bye, jazzkramer.

[Matec]

Yeeessss !!!

Thank you build, for his contribution!
When we are not sure about the circuits, we will see that this mod you asked.

Littlewyan, is easy. C8 is located between the anode and cathode of V2A.

C12 is in parallel with the resistor R18 of the attenuator circuit. It is equal to the attenuator JCM1.

Yeess!!

[jazbo8]

Big thanks to build and jazzkramer! We will get these buggers sorted out soon...